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Secure Ad Hoc Group Communication Using PKI

1. Fig 13 Participation Manager Tier Event Model 28 When protocol events occur in the manager tier they are relayed to the application through the event interfaces specified in the model There is a one to one mapping between event listeners and participation managers Class GroupEventListener specifies the events which are generated by the GroupParticpationManager Classes implementing this event interface are notified when messages are received when providers and subscribers come online or go offline and when other status messages ate generated by the manager Class ProviderEventListener is a very simple listener with only one event This event is fired by the ProviderParticipationManager when a new incoming download request is received from a subscriber Class SubscriberEventListener specifies events related to the download of songs by a subscriber These events are fired by the SwbscriberParticipationManager when a download is started completed or an error occurs during while executing the protocol Application Manager Tier This tier acts as the controller between the view tier and the manager tier Actions requested in the view are passed through this tier to the appropriate manager In addition events generated through the manager tier s event model are aggregated in this tier and relayed up to the view This tier also handles most of the necessary security for the application Below is a diagram of the classes which make up t
2. S Fig 3 Computing amp Verifying Signatures To compute a signature first the sender hashes the message to be sent The resulting hash is then used to seed a PRNG which is then used to generate a random plaintext element rin the domain appropriate for the public key algorithm being used The signature s is computed by decrypting r with the sender s private signing key Ky The message and signature can then be sent to its intended recipient Once the message is received the signature 1s vetified in much the same manner as it was originally computed The message is hashed and used to seed a PRNG From this the random plaintext element ris generated Then the signature received s is encrypted using the signature verification key K to yield 7 The signature is determined to be valid if A ei Ena P L 11 Public Key Infrastructure Public key infrastructure PKI provides a framework for establishing and authenticating secure communication between distributed parties It is a trust based system wherein an empowered third party may create verifiable digital identities for users or devices This third party is more commonly known as a certificate authority and the digital identities as certificates Certificates are digitally signed so their content may be verified as authentic They also bind public key information to a user or device enabling secure communications to be initiated With the algorithmic parts of the publ
3. int Q getRowCount int O getTableHeader JTableHeader Q getSongInfoRowAt SongInfoRow Q getTableModel TableModel Q getValueAE Object Q getValueAt Object SongCollectionTableModel 1 overload Q isCellEditable boolean isSorting boolean Q modelIndext int Q setColumnComparator void Nested Types gt SongInfoRow Class Q setSortingStatus void T Q setTableHeader void G Fields Q setTableModel void Q setValueAt void Nested Types song SongInfo user String Fig 16 Graphical View Support 3T Class Musicl able provides a specialized extension of JTable suited for the display of song information and is used extensively through out the view Class Tab eSorter provides the ability to sort these song information tables by column It should be noted that this class was obtained from Sun s Swing Tutorials 6 This functionality has since been absorbed into the Swing library with the recent release of Java6 but since this application is designed to be run with Java5 had to be manually included The final class SongCollectionTableModel provides a custom data model for the MusicTable class to display The data model allows the association with of a user with song information and the ability to display this data conveniently in the application For more information regarding usage of the application in each view mode see the User s Manual s
4. O Certificate Authority O User Certificates o Performance Evaluation Script All deliverables mentioned in this section as well as all other documents generated during the coutse of this project may be found on my project website at http www cs rit edu krm4686 msproj 65 Future Work I am fairly happy with the results of this project but as with any project there is always additional work that can be done The public key framework added to the TupleBoard library was designed to easily allow future extensions The addition of additional algorithms to this framework would prove an interesting investigation RSA is a very well known algorithm and has been in use for many years Recently there has been interest in a new type of public key algorithm based on elliptic curves Much like RSA these algorithms can be used for encryption as well as digital signatures Similarly it may be interesting to add additional symmetric key algorithms to the library This would require a new layer of abstraction to allow security contexts to work with algorithms besides Helix the only one currently supported AES the Advanced Encryption Standatd or Phelix a new revised version of Helix may be good places to start Writing this final report has also given me some additional perspective on the project as a whole There are a few things I would do differently if starting again Currently authorization is only supported at the application level It would be b
5. The target provider is notified of the posting of any DownloadRequestTuples matching its providerlD through a listener added to the tuple board during application initialization When a new tuple is received it must be verified that the requesting subscriber is actually authorized to download the requested song The tuple contains an 7sAuthorized method which delegates to the provider authorization certificate to verify its authorization status as described previously in this section The provider must also verify that it actually has the requested song and is authorized to provide it If any of these conditions are not met the request is ignored Otherwise the provider creates a new Jong ransferTuple This tuple is initialized with the same Songlnfo object specified in the request as well as the target and the java io File object containing the requested song in the provider s file system In order to actually transfer the contents of the song file over the network some custom serialization must be done This tuple is based directly on the implementation of the FzeTup found in the edu rit tb tuples package The tuple specifies custom writeOlyect and readOlyect methods which are automatically invoked when the object is serialized and deserialized In addition to the serializable fields of the object the contents of the song file are also written to the object output stream during serialization Similarly the contents of the song file are read
6. 9 createStartup Tuple SignedTuple E Methods Q getMusicLibrary SongCollection y addListener void getRole MusicGroupRoles 5 isAuthentic boolean groupKeyRefreshComplete void 9 postTuple void Q groupKeyRefreshStarting void 9 removeListener void Q initialize RoleParticipationManager 9 withdrawTuplest void a start void l j g9 startListeners void 4 9 stop void stopListeners void GroupParticipationManager A ProviderParticipationManager A SubscriberParticipationManager A Class Class Class gt ParticipationManager gt RoleParticipationManager gt RoleParticipationManager r I Fields I Fields I Fields E Methods E Methods E Methods Q addKeyEventListener void Q groupKeyRefreshComplete void Q groupKeyRefreshStarting void Q removeKeyEventListener void 9 createStartupTuple SignedTuple gY processDownloadRequest void Q startListeners void Q stopListeners void 9 createStartupTuple SignedTuple Q requestSong void Q startListeners void Q stopListeners void Q sendGroupMessage void Q sendPrivateMessage void Q start void Q startListeners void Q statusMessage void stop void 9 stopListeners void Fig 12 Participation Manager Tier The base PartitionManager class provides some functionality common to all types of participation managers in the tier It provides members for the
7. A group user may have one or mote certificates specifying roles and the music authorizations associated with each The class contains a static oadCertificatesFromDisk method to provide easy support for deserializing these certificates for use in the application The certificate also contains an 7sAuthorized method for determining whether a specific song is authorized according to that certificate Music authorizations are performed in a multi tier fashion A song is considered authorized if any of the following are true the song s artist is found in the music collection s artists list or the song s album is found in the music collection s albums list or the song is found in the music collection s songs list Class MusicCertificateAuthority provides the ability to generate MusicAuthorizationCertificate objects The certificate authority must be initialized with the instance of the group s certificate authority so that its certificate signatures may be verified by group members Certificates may be created using the createCertificate method More information regarding generating MausicAutborization Certificates may be found in the User s Manual later in this document 20 Application Protocols With the necessary roles and music authorizations defined tuples and protocols could be designed to enable collaboration between group users Below is a diagram containing all application level tuples used in the system Note that all tuple
8. Bytes None sm Auth Full Linear None Linear Auth lt Linear Full None t 0 00009B 2697 R 0 9958 Rate 88 89 Mbps Overhead 2697 msec Auth t 0 0004B 2752 R 0 9791 Rate 20 00 Mbps Overhead 2752 msec Full t 0 0005B 4177 R 0 9923 Rate 16 00 Mbps Overhead 4177 msec Fig 26 Transfer Times e Rates at Various Security Levels As expected transfer times at all security levels increase linearly with the size of the file In addition the rate of increase itself grows as authentication and encryption are added to the transfer These results clearly illustrate the tradeoff between security and speed It is therefore important to evaluate the environment in which the library is being used and select a security level appropriate for the desired level of performance 38 User s Manual The software described in this user s manual expects that certain jar files be on the class path in order to function correctly Please refer to the Deliverables section found later in this document for more information regarding these required jars Required jar files e latest TupleBoard API tb jar e latest MusicGroup Application musicgroup jar e Java ID3 Tab Library jid3lib 0 5 4 jar e NetBeans 11 Swing Absolute Positioning Library AbsoluteLayout jar required only for graphical MusicGroup client The first entity which must be present in order to establish public key infrastructure
9. Oftype In library userz2 how s it going user2 N explosions Artist lv All E Search user2 indeed my good sir user3 test Results Album Artist Title user3 this application rocks the earth is not a cold dead place explosions inthe sky first breath after coma the earth is nota cold dead place explosions inthe sky the only moment we user2 this is a test of a very long the earth is nota cold dead place explosions inthe sky six days atthe bottom message and such oh yeah Providers Online the earth is not a cold dead place explosions in the sky memorial the earth is not a cold dead place explosions in the sky your hand in mine user3 explosions in the sky is clearly the best band ever user 1 user2 user2 yes indeed my good sir i also enjoy mono 4 il I LE New group message received from user2 Fig 31 Search Here we can see the results of searching for the term explosions in the artist field of all songs in all provider s libraries Queties may also be performed against the title or album fields by selecting the appropriate value in the first drop down box In addition it is possible to search only a single provider rather than all of them To do so simply select the desired provider to be searched from the second dropdown box When the Search button is clicked the search is performed any old
10. Q isPrivate boolean Q sign byte 1 overload 9 signObject byte Q verifyQ boolean 1 overload Q verifyObject boolean Fig 7 Digital Signatures in TB When a SzgnedTuple is created and its signature initialized as described above it is ready to be posted to the tuple board This is done no differently than a standard tuple However upon reading the signed tuple from the tuple board the receiver has the ability to verify its validity and authenticity This operation is provided by the 7sAwthentic method Three separate checks are performed by this method First the enclosed AlgorithmW alletCertificate is checked for expiration If this test passes the CA s signature on that certificate is verified If this check also succeeds then the signature on the tuple itself is verified using the signature verification algorithm found in the certificate In this manner the authenticity of the tuple may be established Additional information regarding how to sign and verify tuples may be found in the Developer s Guide later in this document Details on the specific instances of signed tuples used in this project are presented in the next section Music Group Application Design amp Implementation 17 MusicGroup Application Design amp Implementation Once the security additions to TupleBoard API were complete the second phase of the project could begin The goal of this phase was to create an ad hoc music d
11. and am interested to see what additional projects are done using it and extending it 66 References 1 10 11 Farng Eric Java ID3 Tag Library 2006 http javamusictag sourceforee net index html Ferguson Niels and Schneier Bruce Practical Cryptography Indianapolis Wiley Publishing Inc 2003 Ferguson Niels Whiting Doug Schneier Bruce Kelsey John Lucks Stephan and Kohno Tadayoshi Helix Fast Encryption and Authentication in a Single Cryptographic Primitive In Fast Software Encryption 10th International Workshop FSE 03 volume 2887 of Lecture Notes in Computer Science pages 330 346 Springer Verlag 2003 Gelernter D 1985 Generative communication in Linda ACM Trans Program Lang Syst 7 1 Jan 1985 80 112 DOI http doi acm org 10 1145 2363 2433 IBN s TSpaces Technology Overview Aug 2003 http www alphaworks ibm com tech tspaces The Java Tutorials How to Use Tables http java sun com docs books tutorial uiswing components table html Kaminsky Alan TupleBoard Library http www cs rit edu ark tb shtml Kim Jisoo Group Key Agreement Protocols with Implicit Key Authentication RIT Computer Science MLS project July 2005 Kwon Minseok Secure Group Communications RYT CS Colloquia Series May 15 2007 http www cs tit edu spr CLOABS 1mk1 html Microsoft Cryptography API Reference http msdn2 microsoft com en us library aa380256 aspx NetBeans ID
12. AUthOtity osea s pedet e rel pete Ta eua et eden 40 Gen tatea COP Hecate oe oo es Vocem ue Chad ae te vex bert DUREE VEU V 41 Generate a Music Collection eee sou oes era MERE MEME 42 Generate a Music Authorization CertilfICate i ee serere a rh eU Nae 43 Join a Music Group Command Line CHent ciere e eer bh Rant 45 Join a Music Group Graphical C lent eu cerei ale eria ete ee e nime 51 Developer s Guide Working with Random Numbers eee 58 Working with Public Key Algotit Briss ciui tede o ee cete n reto enit e 59 Working with Digital Sista rites us uso nere Yat uo o ERR ERU e YR D ot ai pd 60 Wotkine with Certificates cien ex RR qe MD P4 op I QR DU Nm EV 61 Working with Secure TupleBoatd torio Rte 62 Deliverables arenaen Zana R iu LUDUM iue 65 Future Wotka iua esie teen red opel opea Devon ui uo da bod de ess 66 AAS hay fcuk O c pdt i dA E MCA PE MESE 67 Overview Secure group communication in an ad hoc netwotk is a largely unexplored research area While there exist group key exchange protocols a recent M S project 8 showed that various forms of the Group Diffie Hellman protocol become computationally infeasible quickly as group sizes increase Moreover currently available protocols were not designed to be implemented in an ad hoc network where nodes sporadically enter and leave the group This project explores establishing secure group communication in an ad hoc network through public key infrastructure Public key infrast
13. Create tuple SecureExampleTuple set new SecureExampleTuple cert message Sign tuple set sign sigAlg Return return set With the tuple defined we may now write the code necessary for transferring one from user to user2 It is assumed that the both users certificates are locally available for this example First the posting code for user1 Read in my certificate AlgorithmWalletCertificate myCert AlgorithmWalletCertificate fromStream new FileInputStream new File userl cert Read in my wallet AlgorithmWallet myWallet AlgorithmWallet fromStream new FileInputStream new File userl wallet Read in user2 s certificate AlgorithmWalletCertificate userTwoCert AlgorithmWalletCertificate fromStream new FileInputStream new File user2 cert Create a new tuple to send SecureExampleTuple t SecureExampleTuple creat myCert Hello user2 myWallet getUserSignatureAlgorithm 63 Create the security context with which to send The security context s id is based on the target recipient s certificate PublicKeySecurityContext pksc new PublicKeySecurityContext new CertificateSecurityContextId userTwoCert userTwoCert getUserEncryptionAlgorithm helixRand Create the tuple board TupleBoard board new TupleBoard Post tuple and wait board post t pksc Thread currentThread join Now the reading code for user2 Read in my cer
14. a key refresh occurs all previously posted group messages are withdrawn Private messages persist until the target user is found to be offline as described in the user announcement protocol above More information on sending and receiving secure group messages may be found in the User s Manual section later in this document 23 Song Transfer Protocol The song transfer protocol is probably the most important protocol in the application since its purpose 15 to enable the secure and authorized distribution of music between group members It is also the most involved While all previously defined tuple protocols involve only a single step this protocol consists of a request and a response A subscriber initiates the protocol by posting a DownloadRequestIupk This tuple is initialized with the song wishing to be downloaded a music authorization certificate which authorizes the download and the target provider that should field the request Much like the private message protocol described in the previous section this tuple should be posted to the tuple board using a PublicKeySecurityContext initialized with the target providers public key encryption algorithm While this is not absolutely necessary since no truly sensitive data is contained in the tuple it does protect the privacy of the subscriber No user but the target provider will be able to discover what song was requested or the collection of songs the subscriber is authorized to download
15. allows querying for specific albums artists or songs from specific providers or the entire group based on the command syntax chosen Result matching is performed on a substring basis only Songs are determined to match the query if the song field album artist or title contains the query or vice versa To search all providers for a song by title gt search all title flames beyond the cold mountain userl s library mono the flames beyond the cold mountain gt To search a specific provider for a song by title gt search user2 title flames beyond the cold mountain No results found gt 47 The previous two queties searched for matches by title Artists or albums may also be queried by replacing the title keyword with artist or album respectively gt search all artist explosions user2 s library explosions in the sky first breath after coma gt Messaging The application supports two types of messaging protocols Group messages are able to be received by each user currently participating in the group In contrast private messages are only able to be read by their target recipient Incoming messages are relayed through the system message queue as described earlier in this section To send a group message use the gm command gm this is a public message gt That command would cause the following system message to appear on each group user s console Publ
16. application rocks you are there Downloading explosions in the sky your hand in mine x fest of a very long you are there you are there 3 ch oh yeah so alae BE you are there TMy Computer L B s in the sky is clearly know by heal FW ey nest i Local Disk C t amp Shared Documents amp My Sharing Folders S Local Disk D S DVD CD RW Drive E Providers Online user 1 user2 d my good sir i also File Name explosions in the sky your hand in mine mp3 Files of Type MP3 Files Save Cancel New private message received from us Fig 32 Download Prompt Select a suitable place to save the file click the Save button to initiate the download request System messages will be displayed in the status bar area both when the transfer begins and when it has completed Download started explosions in the sky your hand in mine Download completed path to file explosions in the sky your hand in mine mp3 The above exchange assumes that subscriber user1 is authorized to download the song explosions in the sky your hand in mine and that provider user2 is authorized to provide it If either of these are not the case error messages will be received instead Song Transfer Log A feature unique to the graphical client is the song transfer log This view functions as a song transfer history and lists all files which have bee
17. great I il gt New group message received from user2 Fig 30 Group Library Here we can clearly see all the songs available for user2 the only other provider currently online Note that if the current user is also a provider the corresponding library is excluded from this view since all entries will already be shown in the My Library view and secondly it would not make sense to download a song from oneself The above view has also been sorted by title in ascending order to illustrate the previously mentioned sorting abilities Music Search Manually browsing through the Group Library view can become tedious especially if providers have large libraries or there are many providers currently online The search interface located in the next tab to the right labeled Search allows querying for specific albums artists or songs from specific providers or the entire group based on the options chosen Result matching is performed on a substring basis only Songs are determined to match the query if the song field album artist or title contains the query or vice versa This view is analogous to the search command in the command line client 53 Z MusicGroup Subscribers Online MyLibrary Group Library Search Transfers Private Messages Group Messages user1 user3 Search for
18. methods simply return new instances of the PublicKeyInputStream and PublicKeyOutputStream classes pictured above These classes handle the generation encryption and decryption of the symmetric key and then delegate all further I O to the HelixInputStream and HelixOutputStream classes The implementation of these two classes is based largely on the protocol established between the two Helix streams The following diagram illustrates the steps performed when transferring a tuple posted to the tuple board using the PublicKeySecurityContext Sender PublicKeyAlgorithm Ker Initialize Receiver y PublicKeyAlgorithm PublickeySecurtyContext Kar Kar Generate Random r Initialize y x E r r er ai PublicKeySecurityContext D r D x e y r Hash Hash DoubleSHA 256 DoubleSHA 256 Ka Kh N E Plaintext MAC HelixOutputStream h HelixInputStream Dy Ciphertext T Verify MAC y Plaintext Plaintext Fig 6 Public Key Encryption First the sender initializes a new instance of PublicKeySecurityContext with the public key algorithm of the target user and posts a tuple to the board using this context When the tuple is read by the receiver a new PublicKeyOutputStream is created on the sender side This object generates a random plaintext element r using the generateRandomPlaintext method of the public key algorithm It then computes x b
19. obtain and harder to evaluate its quality Luckily it is easy to obtain pseudorandom data seemingly random sequences of bytes deterministically generated from an initial seed Java provides a pseudorandom number generator PRNG class java util random but this is not sufficient for use in cryptographic protocols An obvious application of a PRNG is creation of encryption keys However a standard PRNG is often predictable and if broken compromises the integrity of all keys it generates To combat this problem we need a cryptographically strong PRNG one that eliminates the predictability factor While Java also provides a cryptographically strong PRNG in class Java security SecureRandom Professor Kaminsky asked me to create my own implementation for the TupleBoard API Luckily it is fairly straightforward to create a PRNG from a stream cipher such as Helix Stream ciphers generally encrypt a plaintext by XORing it with a randomly generated key stream initialized with the encryption key Here the key is analogous to the seed of a PRNG and the key stream represents the sequence of randomly generated bits Class edu rit crypto helix HelixRandom provides a ctyptographically strong PRNG based on the Helix cipher HelixCipher Class gt 7 HelixRandom amp Fields c Methods z 4 Q decrypt int 1 overload Fields 7 cipher Q decryptNext int Methods Q encrypt int 1 overload aY generateRand
20. results are cleared from the results view and the new results are loaded If no results match the specified query the results view will simply remain empty Downloading Songs No file sharing application would be a file sharing application without the ability to download songs Song downloads may be initiated from both the Group Library and Search views In the Group Library simply double click the table row containing the desired song and provider After a search simply double click the results table row containing the desired song and provider This action will launch a download prompt similar to that pictured below This behavior is analogous to invoking the download command in the command line client 54 zii Subscribers Online MyLibrary Group Library Search Transfers Private Messages Group Messages user 1 user3 Album Artist user2 how s it going TES the earth is not a cold dead place explosions in the sky first breath after co the earth is not a cold dead place explosions in the sky the only moment the earth is not a cold dead place explosions in the sky six days atthe botti the earth is nota cold dead place explosions in the sky memorial the earth is nota cold dead place you are there explosions inthe s mono our hand in mine the flames beyond you are there mona a hearthas asked user2 indeed my good sir user3 test user3 this
21. returning to the shell from which it was started 57 Developer s Guide With the many additions made to the TupleBoard API during the project it is useful to provide some developer s suggestions and small code samples demonstrating how to get the most out of the new security functionality Working with Random Numbers As mentioned in the section detailing the design and implementation of the newly added Helix cipher based pseudorandom number generator HeZxRandom a PRNG s data is only as good as its seed When working with this class it is important to initialize it with a proper truly random seed Fortunately Java5 makes it fairly easy to do so Class java security SecureRandom provides the ability to generate seed bytes to be used with other PRNGs The underlying manner in which these seed bytes are created differs from system to system In Linux and UNIX based environments there is an entropy source provided at the OS level through the dev random ot dev urandom devices The Windows platform has no analogous file but enables randomness to be obtained through the native CryptoAPI 10 Java uses a system property securerandom source to control the entropy source when generating seeds As long as the value of this property is set to file dev urandom Java will automatically use the correct entropy source for the environment This is the default value Using HelixRandom is easy The following code sample illustrates initializing
22. specified Generation of a 2048 bit RSA RSAWithDoubleSHA256 certificate takes approximately 8 10 minutes on a 650MHz SparcV9 CPU or 1 minute on a 1 8GHz Pentium M CPU Example 2 java edu rit tb security cert CertificateAuthority generate groupOne ca 06 07 2007 07 07 2007 userl userl cert userl wallet Creating user encryption amp signature public and private key pairs Writing certificate to home stu9 s15 krm4686 courses msproj data userl cert Writing wallet to home stu9 s15 krm4686 courses msproj data userl wallet 9e gt Generate a Music Collection Once a certificate and wallet have been generated as in the previous step the user is now capable of interacting with an arbitrary group In order to participate in a music group however some additional certificates are required that of a provider and subscriber The first step in generating these is to create a MusicCollection object This is a list of all artists albums and songs a provider or subscriber is permitted to upload or download respectively To generate a music collection java edu rit tb music meta MusicCollection lt albumsFile gt lt songsFile gt artistsFile lt outFile gt Note VY denotes a line continuation there should be no newlines in the argument list gu 41 Argument descriptions albumsFile The text file containing authorized albums Each line should be formatted so it may be parsed into an A bumInfo o
23. stores these algorithms in an 74 eorzbiuW allet which is simply a data holder class for public key algorithms Instead of keys the wallet contains instances of the algorithms initialized with the necessary keys The wallet may also be public or private A private wallet contains public key algorithms capable of both encryption and decryption and therefore capable of creating and verifying signatures A public wallet may only encrypt data and verify signatures In this manner the user may keep the private instance of the wallet but distribute the public instance in an AlgorithmW alletCertificate so other users may verify the user s signatures and also send encrypted messages capable of being decrypted only by that user With the certificates defined there now needs to be a certificate authority to generate them Class CertificateAuthority provides this capability The CA is created with a name public key enctyption algorithm and a signature algorithm The CA s name serves as the group ID The public key algorithm is included in all certificates created and allows group users to encrypt messages only other certificate possessing users have the capability of decrypting The signature algorithm is used to digitally sign each certificate generated The createAlgorithmW alletCertificate method performs the creation of the certificate Invoking the method results in the creation of two files one containing the user s serialized private wallet and the o
24. the earth is not a cold dead place explosions in the sky first breath afte user2 the earth is not a cold dead place explosions in the sky the only mome user2 ves indeed my good sir i also the earth is not a cold dead place explosions in the sky Six days atthe enjoy mono the earth is not a cold dead place explosions in the sky memoarial the earth is not a cold dead place explosions in the sky your hand in m you are there mono the flames bey you are there mono a heart has as you are there mono yearning you are there mono are you there T 7 Imana l The amanen New group message received from user2 Fio 29 My Library This tab contains a list of all songs loaded from any lt mediaLibrary gt arguments found on the command line at application start See the beginning of this section for more information on arguments This view is analogous to the list my command in the command line version of the client Song tables like the one pictured above occur throughout the various tabs in the application All tables may be sorted by clicking on the column header which corresponds to the data field to be sorted on Clicking once will sort the data in ascending order Clicking again will sort the data in descending order Clicking once more will reset the data to its original ordering What Songs Are Availabl
25. use the online command online subscribers Subscribers online userl user2 user3 user4 gt The same syntax is used to view the list of providers currently online by replacing subscribers with providers Providers online userl user2 user3 user4 gt What Songs are Available Since this is a music sharing client it is useful to be able to browse the available catalogs for each provider currently online This functionality is implemented through the list command There are three different versions of this command To view the songs currently available from all providers in the group gt list all userl s library the american analog set aaron and maria mono the flames beyond the cold mountain user2 s library explosions in the sky first breath after coma mono yearning gt 46 To view the songs currently available from a specific providet list user2 user2 s library explosions in the sky first breath after coma mono yearning gt To view the songs in my library gt list my userl s library the american analog set aaron and maria mono the flames beyond the cold mountain gt Music Search Manually browsing through the output of the list command can become tedious especially if providers have large libraries or there are many providers currently online The search command
26. E http www netbeans org 67
27. Fig 34 Private amp Group Messages Private conversation windows like the one pictured above are automatically created in the Private Messages tab when a new private message is received from another user in the group To initiate a new private conversation with another group user simply locate the user s ID in one of the online user lists in the left zone and double click The private message interface will automatically gain focus and a new conversation window will be created for the target user Sent and received messages are logged in the top text area while messages to be sent are entered in the bottom text area The message is sent once the Enter key is typed This behavior is analogous to the pm command in the command line client Group messages or public messages as they are also known are sent and received in the Group Messages pane in the right and final zone The behavior of the group message interface is identical to that of the private message conversation windows Sent and received messages ate logged in the top text area while messages to be sent ate entered in the bottom text area The message is sent once the Enter key is typed This behavior is analogous to the gm command in the command line client Quitting the Application When finished interacting with the music group simply close the application window All tuple board interactions will be immediately ceased and the application will shutdown
28. M S Project Report Securing Tuple Space Secute Ad Hoc Group Communication Using PKI Kyle R Morse Rochester Institute of Technology Department of Computer Science krm4686 a cs rit edu Committee Chair Professor Alan Kaminsky Reader Professor Hans Peter Bischof Observer Professor Stanislaw Radziszowski Table of Contents SYS dS NRI m 4 AINE a NOTIS 1e ud ER ash veamos yo aed a ral eaters Hae spar 5 Secure TupleBoard API Design amp Implementaion Genetaunp Bandofnessocdespteina eod ere tenqoer qa odi Aes tesi dus do 6 Public Key X oRtmssece netto sat nw tania ect seer Rol SEU OE Dd reges 7 Public Key Infrastructute aig seis tn dea ir nae aa E EE 12 Publie Key BBOryplomnin TB here ereng i E S rd ER T SE 14 Digit l Signatures i0 I Diii erede eoe ine a A NR RE T AET Eia ery 16 MusicGroup Application Design amp Implementation Song Metadata stp ne Leader qe Pl EA a Es 18 Roles Gc ST hOFIzALOEB neroaren t dor Eni EER A ta esos d rostris 19 Applicaton Protocol serere orem bx pra psa uoo le uic EEE Aan 21 Applicaton Ate MIRE CURES eis ee etre Rare NER eus reca n ENEE Y aat 25 Performance Evaluation Raw Lransfer Dies eaa de ope UE MER RH Vo eoa RE OE EE EE NER 34 Signature Verification TUNG Lese conse cox ero A xy tie Pb ETH Vo tH ap o 35 Encrypted Transfer Time 5 ro pu hey s unto abesset aS debes urat n 36 Authenticated amp Encrypted Transfer Timeo eet eel 37 ST TT 38 User s Manual Create a Certificate
29. S R 0 9891 6000 oO 4000 2000 0 5000000 10000000 15000000 20000000 25000000 File Size Bytes Fig 22 Encrypted Transfer Time 36 Authenticated amp Encrypted Transfer Time This test was performed in order to compare the total tuple transfer time using both enctyption and authentication to the baseline raw transfer The public key algorithm used is 2048 bit RSA The symmetric key algorithm used is 256 bit Helix The signature algorithm used is 2048 bit RSA with Double SHA 256 File 1 File 2 File 3 Mean A amp E Transfer Time msec 5678 76 10756 11 16090 37 Fig 23 Mean Authenticated e Encrypted Transfer Times Authenticated amp Encrypted Transfer 18000 16000 14000 12000 y 0 0005x 4177 3 R 0 9923 10000 8000 6000 Time Milliseconds 4000 2000 0 5000000 10000000 15000000 20000000 25000000 File Size Bytes Fig 24 Authenticated amp Encrypted Transfer Time 37 Summary Once all testing data was gathered it could be condensed and analyzed for further performance comparison None Auth Full File 1 2959 19 3831 77 5678 76 File 2 3840 89 7261 05 10756 11 File 3 4770 88 11068 69 16090 37 Fig 25 Mean Total Transfer Times at Various Security Levels a ge c 8 8 o E E 5000000 10000000 15000000 20000000 25000000 File Size
30. a new instance of the PRNG with seed bytes obtained as describe above and then generating 100 random bytes Initialize seed generator SecureRandom seedGen new SecureRandom Generate seed bytes byte seedBytes seedGen generateSeed 48 Create new HelixRandom HelixRandom helixRand new HelixRandom seedBytes Now random bytes may be obtained byte randomBytes new byte 100 helixRand nextBytes randomBytes Fig 35 Generating Randomness with HelixRandom 58 Wotking with Public Key Algorithms Currently the TupleBoard library supports one public key encryption algorithm RSA Instances of the algorithm may be obtained through the provided algorithm factory class PKLA oritbmFactory The factory automatically generates the necessary keys according to the bit strength specified While any number of bits may be used a value of 2048 is recommended as a minimum to achieve a reasonable level of secutity Specify the bit strength of the algorithm to be created int bitStrength 2048 Obtain an instance of RSA PublicKeyAlgorithm rsa PKIAlgorithmFactory createEncryptionAlgorithm EncryptionAlgorithms RSA bitStrength helixRand Fig 36 Obtaining an instance of RSA Once an instance of RSA has been obtained it may be used for encryption RSA operates on instances of java math BigInteger so a plaintext message must be represented as a number p such that p lt n the public RSA m
31. be empty Similarly if the current user does not have the provider role enabled the upload log will be empty Messaging Like the command line client the graphical client supports two types of messaging protocols Group messages are able to be received by each user currently participating in the group In contrast private messages are only able to be read by their target recipient Incoming messages are relayed through the system message queue and displayed in the status bar area as described earlier in this section The graphical client also additional interfaces for sending and presenting received messages both public and private Private messages may be sent and received from the last tab in the center zone labeled Private Messages 56 MusicGroup Se x Subscribers Online My Library Group Library Search Transfers Private Messages Group Messages user 1 user3 Iser2 user2 how s it going user2 user3 user2 indeed my good sir user this is a private message user3 test user2 this is a reply to your private messages user3 this application rocks user2 this is a test of a very long message and such oh yeah Providers Online user3 explosions in the sky is clearly Ihe best band ever user 1 user2 user2 yes indeed my good sir i also enjoy mono New private message received from user2
32. bject through the AlbumInjo fromAlbumlnfoS tring method Format year artistName albumName lt songsFile gt The text file containing authorized individual songs Each line should be formatted so it may be parsed into a Songlnfo object through the Sonelnfo fromSonglnfoString method Format year artistName albumName trackNumber title lt artistsFile gt The text file containing authorized artists Each line should contain a single string representing the artist s name Format artistName outFile The file to which the resulting MusicCollection object will be serialized for persistent storage The program will parse the three input files into their appropriate collections AlbumCollection SongCollection and ArtistCollection respectively A new MusicCollection object created from these collections is then serialized to disk at the specified location Example gt java edu rit tb music meta MusicCollection albums txt songs txt artists txt userl mc Parsing album collection Parsing song collection Parsing artist collection Writing music collection to home stu9 s15 krm4686 courses msproj data userl mc oe gt Generate a Music Authorizations Certificate Now that a music collection has been generated certificates may be created for participation in the music group Class edu rit tb music cert MusicCertificateAuthority contains a main method capable of generating provider and subscriber certif
33. c distributed applications in Java This middleware library is the basis for all work done during this project While the main focus of the project is adding security to the TupleBoard library an equally important second step is the development of an application showcasing the newly added features The market for digital music has exploded in recent years Unfortunately much of the media available from online music outlets e g Tunes Napster is crippled by the plague of DRM Digital Rights Management Therefore I created an ad hoc music distribution network which does not infringe on fair use rights but also provides resistance to piracy through the encryption authentication and authorization mechanisms developed during the project Related Work In order to establish secure group communication the exchange of encryption keys is required In the simplest group consisting of only two usets the standard Diffie Hellman key exchange may be used In this protocol Alice chooses values a g and p and sends g p and 7 mod p to Bob Bob chooses value b and sends mod p back to Alice Both parties ab may now compute the shared key as 2 mod p The original protocol has some shortcomings It is vulnerable to man in the middle attacks if authentication is not performed on the exchanges In addition it does not scale well when expanded from the simple one to one case described above to the many to many case found in the group setting In 8 K
34. c key algorithm is much more computationally expensive than the same operations in a symmetric key system Because of this the use of public key cryptography is generally limited in practical applications to situations where the amount of data to be encrypted is small In the TupleBoard library it used for exchanging symmetric keys and digital signatures When designing this part of the API I tried to make it as general as possible to allow for additional algorithms to be added in the future f PKIAlgorithmFactory a Class T E Methods createEncryptionAlgorithm PublicKeyAlgorithm Q createSignatureAlgorithm SignatureAlgorithm Nested Types EncryptionAlgorithms E3 Enum RSA SignatureAlgorithms D Enum RSAWithDoubleSHA256 C createSA w createPKA D A AAAAA A CORPO MM L 215101210151515102212 2 15 010121 9 otto SignatureAlgorithn 81 PublickeyAlgorithm 3 Abstract Class 1 Abstract Class i 7 7 Fields f E Fields 0 algorithmType EncryptionAlgorithms y bitStrength int E Methods w createPublicInstance PublicKeyAigonithm T gt decypt T decryptFromStream T encypt T encryptToStream void w generateRandomPlaintext T getAlgorithmType Encryption lgorithms getBitStrength int D Private boolean p algorithmType SignatureAlgorithms 9 bitStrength
35. cate is then serialized to disk at the specified location Example gt java edu rit tb music cert MusicCertificateAuthority subscriber groupOne ca 06 07 2007 09 07 2007 userl userl mc userl sub Loading certificate authority Loading music collection Creating certificate Writing certificate to home stu9 s15 krm4686 courses msproj data userl sub oo gt 43 Join a Music Group Command Line Client Once all the previous steps have been completed it will be possible to run the MusicGroup application There are two versions of the application a text based command line client and a Swing based graphical client This section describes how to use the command line version java edu rit tb music MusicGroupCMD userID lt groupID gt lt certDir gt provider musicLibDir subscriber musicLibDir Note V denotes a line continuation there should be no newlines in the argument list Argument desctiptions lt userID gt The unique identifier of the user participating in the group lt groupID gt The identifier of the group to be joined This corresponds to the name of the CA which generated the specified user s certificates lt certDir gt The directory containing all relevant certificate files necessary for group participation provider lt musicLibDir gt This argument set specifies that the application enable the provider role All valid MustcAuthorizationCertificate fil
36. cation Time This test was performed in order to determine how much time signature verification by the reading process contributes to the total transfer time The signature algorithm used is 2048 bit RSA with Double SHA 256 Here the song data is transferred in the clear but the received SongTranferTuples signature is verified Note that these timing measurements reflect only the time to verify the signature not the time to transfer the data File 1 File 2 File 3 Mean Signature Verification Time msec 868 57 3384 25 6144 92 Fig 19 Mean Signature Verification Times Signature Verification 7000 6000 5000 4000 3000 y 0 0003x 87 295 R 0 9999 2000 Time Milliseconds 1000 0 5000000 10000000 15000000 20000000 25000000 File Size Bytes Fig 20 Signature Verification Time 35 Encrypted Transfer Time This test was performed in order to determine how much time encryption and decryption during tuple transfer contributes to the total transfer time The public key algorithm used is 2048 bit RSA The symmetric key algorithm used is 256 bit Helix No signature verification is performed by the reading process File 1 File 2 File 3 Mean Encrypted Transfer Time msec 4812 44 7321 86 9920 45 Fig 21 Mean Encrypted Transfer Times Encrypted Transfer 12000 10000 Z 8000 S y 0 0002x 4082 3
37. cationManager with which it registers itself as the necessary event listeners at startup The first view a simple command line interface is implemented in class MusicGroupCMD In this view events received from the lower tiers are simply printed to standard out Users may interact with the system via a predetermined set of commands All basic application functionality is supported by this view including sending and receiving group and private messages downloading songs and searching The second view implemented in class MusicGroupGUI uses Swing to provide a graphical interface This view is much more involved than the simple command line interface and so requires some additional supporting classes detailed below 5 MusicTable Class O gt JTable T MusicGroupGUI Class 9 libraryview G Methods gt JFrame Q addRow void Q getSelectedSongInfoRow SongInfoRow Q setMadel void modelSorter SongCollectionTableModel D TableSorter B Class Class AbstractTableModel AbstractTableModel 7 7 Fields E Methods d columnHeaders String ae cancelSorting void d rows List lt SongInfoRow gt a clearSortingState void Methods Q getColumnClass Class 9 addRow void Q getColumnCount int Q getColumnName String Q getColumnClass Class Q getRowCount int Q getColumnCount int Q getColumnName String 7 songModel getSortingStatus
38. e Even more useful is the ability to browse the available catalog for each provider currently online The complete list of all available songs and their providers may be viewed by clicking the next tab to the right of My Library labeled Group Library This view is analogous to the list all command in the command line version of the client 52 Z MusicGroup ISI x Subscribers Online MyLibrary Group Library Search Transfers Private Messages Group Messages user 1 k SU Artist Title User user2 how s it going mono a heart has asked for the pleasure user2 user3 e KE A the american analog set aaron and maria user2 user2 indeed my good sir mono are you there user2 e lexplosions in the sky first breath after coma user2 user3 test e explosions in the sky memorial user2 mono moonlight user2 user3 this application rocks e explosions in the sky six days atthe bottom ofthe ocean user2 LE mono the flames beyond the cold mountain user2 user2 this is a test of a very long e explosions in the sky the only moment we were alone user2 message and such oh yeah B mona the remains ofthe day userz F lt mono yearning user2 user3 explosions in the sky is Ace See e explosions in the sky your hand in mine user2 clearly the best band ever user1 user2 user2 yes indeed my good sir i also enjoy mono user2 hi user2 this song is
39. ection found later in this document 32 Performance Evaluation Good security never comes for free In order to establish the impact of encryption and authentication on performance in the library I created a small test program edu rit tb music test PerformanceEval This program times how long each operation takes during the transfer of a SongTransferTuple from one device to another Usage gt java edu rit tb music test PerformanceEval certificate wallet lt file gt provider subscriber none auth full The first two arguments specify the paths to the device s public A gorithmW alletCertificate and private A eoritbiuW allet respectively The third argument specifies the path to the file to be transferred The fourth argument specifies this process as the posting provider or reading subscriber process Finally the last argument specifies the security level of the transfer operation A value of none causes the tuple to be posted using the DefaultSecurityContext and to not be authenticated by the reading process A value of auth causes the tuple to still be posted using the DefaultSecurityContext but the signature is verified by the reading process A value of full causes the tuple to be posted using the PublicKeySecurityContext and the signature to also be verified by the reading process Note that the posting process will post the SongTransferTuple and wait until killed externally while the read
40. ecurity contexts Any tuples which were posted using the old context are also withdrawn at this time User Announcement Protocol Once the symmetric key security context is initialized as described above the application may notify any other users currently participating in the group of its arrival It may also gather information regarding the other users online and their roles This is the essence of the user announcement protocol 22 The two tuples involved in this protocol are the ProviderTupk and the SubscriberTupk These tuples are posted to the board using the newly initialized group FzxedHe zxSecurityContext when a user authorized as a provider or subscriber begins participating in the group Both tuples contain the user s A gorithmW alletCertificate enabling private communications with the user and the ability to verify signatures on tuples received from the user The ProviderTuple also contains a SongCollection representing the catalog of songs the provider is authorized to provide and has available for download Existing group users are notified of the posting of these tuples through listeners added to the board during application initialization The listeners also are notified when these tuples are withdrawn signaling that a user has left the group Through this protocol a current list of the users online and their roles may be maintained Secure Messaging Protocol The application supports the sending and receiving of encrypted mes
41. en down by category and search breadth View Tier The final tier in the application is the view This tier allows interaction with the user sends collected user actions to the application manager tier and displays events and notifications received from the lower tiers gt MusicGroupC MD Class T MusicGroupGUI A Class zi Methods gt JFrame 9 downloadComplete void 7 downloadError void Fields MN AUTRES void i Methods e babe b ed 800 cwn downloadComplete void i es vag X downloadError void rs privateMessageReceived void Q downloadRequestedFromSubscriber void providerOffline void 9 downloadStarted void providerOnline N veld Q privateMessageReceived void Q publicMessageReceived void M provider orane i vold run void Q providerOnline void start void Q publicMessageReceived void Q statusMessage void Q start void stop void Q statusMessage void e rum Offline void Q subscriberOffline void Q subscriberOnline void subscriberOnlineQ void w applicationManager applicationManager ApplicationManager Class securityManager GroupSecurityManager y Class Fig 15 View Tier 30 Two different views compose this tier Each view implements all event listener interfaces defined by the participation tier s event model Both views also contain an instance of class Appli
42. enceTuple providerID String subscriberID String Q getID long 5 Methods Methods getSessionSymmetrickey byte Q create ProviderTuple create SubscriberTuple Q getAvailableMusic SongCollection N Fig 10 Application Protocol Tuples 21 Key Exchange Protocol The first protocol necessary to facilitate group communication in the application is the establishment of a group symmetric key Luckily this is trivial because of the public key infrastructure in place Recall that each user has an AlgorithmW alletCertificate containing the public portions of its encryption and signature algorithms and a corresponding AlgorithmW allet containing the private portions The wallet contains an instance of the group public key encryption algorithm Using this algorithm it is possible to post encrypted tuples only other group members will be capable of decrypting If this is the case why is it necessaty to cteate a group symmetric key Technically it is not necessary All communication could be done securely using the group public key algorithm however this is inefficient Every time a tuple is read the associated PublicKeySecurityContext would have to decrypt the new random symmetric key and initialize a new Helix cipher By creating a group symmetric key each user may initialize one instance of FixedHehxSecurityContext for all groupwide communication The establishment of a group symmetric key is done using the Grou
43. eneficial to integrate a role based authorization mechanism directly into the TupleBoard I would also create a set of SzgnedTupleListeners which would extend the PoszLzsteners and PostWithdrawListeners to allow for automatic authentication of read tuples before triggering posted events Both the application and the library were designed and developed for Java5 Upgrading to Java6 would provide some interface improvements and simplifications for the graphical client due to additions to the javax swing package Automatic table sorting and filtering as well as custom rendering on menu tab strips to enable close buttons on the private conversation tabs would be the first things that could be improved Finally as with any trust based system there are some assumptions made regarding observing protocols and behaving in the expected manner This illustrates the importance of a certificate authority only distributing certificates to users known to be good While it is impossible to prevent all misuse an easy improvement would be the inclusion of mp3 file hashing in the authorization certificates This could prevent the modification of ID3 tag data in files to allow distribution of files masquerading as authorized files between users But again this can do little to stop malicious activity between colluding users since it would be easy to sidestep the protocols in place I think the secure TupleBoard provides an excellent ad hoc collaborative application base
44. er traditional tuples are used SzgnedTuple adds fields for an AlgorithmW alletCertificate and a signature The class may not be directly instantiated as its constructor is protected Subclasses should provide a static create method in which the object is fully initialized and signed before being returned The signature is computed using the SzgnatureAlgorithm specified at creation time in the manner described previously The message being signed is generally the serialized contents of the object itself An example of this usage may be found in the Developer s Guide later in this document Below is the overall design of the digital signature implementation in TB 16 J Serializable gt Tuple amp SignedTuple Class Class g gt Tuple E Methods d Q equals boolean E E Methods 9 hashCode int Q getCertificate AlgorithmWalletCertificate lt isMatchable boolean Y getSignature byte 49 toStrina String 9 isAuthentic boolean av verifyCASignature boolean aY verifyUserSignature boolean signTuple w cert e AlgorithmWalletCertificate A SignatureAlgorittyn D Class Abstract Class F T Iz Methods Methods Q getUserEncryptionAlgorithm PublicKeyAlgorithm Q createVernficabiondtigorithm SignatureAlgorithm Q getUserSignatureverificationAlgorithm SignatureAlgorithm Q getAlgorithmType SignatureAlgorithms Q getBitStrength int Q getOneWayHash OneWayHash
45. es located in the certificate directory will be loaded All authorized song files located in the specified music library directory or any of its subdirectories will be added to the provider s list of available songs subscriber lt musicLibDir gt This argument set specifies that the application enable the subscriber role All valid MusicAuthorizationCertificate files located in the certificate directory will be loaded All song files located in the specified music library directory or any of its subdirectories will be added to the subscriber s current media list Note At least one of these role argument sets must be specified It is also valid to specify both On start up the application will search for and deserialize the user s certificate and wallet files enable the specified role s load each role s song collection metadata and join the group It will then prompt for input and respond to user commands as they are entered For additional details on the protocol for joining a group and other group interaction including sending messages and transferring files please refer to the MusicGroup Application Design amp Implementation section found earlier in this document Example gt java edu rit tb music MusicGroupCMD userl groupOne data provider music subscriber music 44 Initializing application manager Reading existing group data No existing group data found Subscriber online userl Provide
46. f a custom tuple its signing its encrypted transfer through the tuple board and its authentication This example assumes two certificates sets have been generated as in the previous example for users with id s userl and user2 First we define the sample tuple This class represents a very simple extension of SignedTuple providing only a simple message field of type String M public class SecureExampleTuple extends SignedTuple Tuple payload a simple String message a public final String message Template constructor This constructor is suitable for creating default templates The message field is initialized o null P public SecureExampleTuple this final null 62 Tuple constructor This constructor is suitable for creating a tuple with a message for posting Instances of this class may not be created using this constructor Instead use the provided factory create method P protected SecureExampleTuple AlgorithmWalletCertificate cert String message super cert this message message Factory create method A new instance of this tuple is created with the specified certificate and message The tuple is signed using the specified algorithm before being returned XE public static SecureExampleTuple creat AlgorithmWalletCertificate cert String message SignatureAlgorithm sigAlg throws IOException
47. face compatible with the new PublicKeySecurityContext defined later in this document This allows any extending algorithm classes to be simply plugged in and used to securely post tuples to the tuple board Similarly class SignatureAlgorithm provides common signature algorithm fields and behaviors and allows for an extending class to compute and verify digital signatures using any combination of OneWayHash and PublickeyAlgorithm RSA With the interfaces defined the next step was to develop a concrete implementation of a public key encryption algorithm RSA is probably the most well known algorithm in this category It is also quite easy to implement in Java thanks to the java math BigInteger class which already includes methods for performing modular exponentiation primality testing and modular inverse calculation RSA is elegant in its simplicity The basic parameters of the algorithm include e the encryption exponent d the decryption exponent and z the composite modulus Encryption and decryption are both only a modular exponentiation operation To encrypt c m mod n To decrypt m c mod n although this operation can be sped up using additional private parameters and Chinese remaindering The first step in implementing the algorithm is to generate the composite modulus 7 The algorithm I implemented for doing so is taken from Practical Cryptography 2 The modulus is defined to be the product of two large primes so the first
48. from the object input stream when the tuple is deserialized Since the signature on the tuple is computed by first serializing it the signature includes the file contents Thus when the tuple is received both its authenticity and integrity of the file transfer may be verified This tuple is posted to the tuple board by the provider using a PublicKeySecurityContext initialized with the subsctiber s public key algorithm so no other users may decrypt and obtain the transferred file data When the subscriber reads this response tuple the song file s contents are written to a temporary file This file is then copied to the location specified by the subscriber when the download request was first made For more on how to download tuples using the application see the User s Manual section located later in this document 24 Application Architecture With the tuple protocols designed and implemented the remainder of the application could be developed The application is written in multiple tiers in order to minimize coupling and increase reuse of developed components The following diagram illustrates the manner in which the application 1s organized View Actions Events ApplicationManager Actions Actions Events Events GroupParticipationManager RoleParticipationManagers Events Events lt Tuple gt lt Tuple gt KeyListener GroupEve
49. he left zone What Songs Do I Have Since this is a music sharing client it is useful to be able to see what songs are already in the user s library 51 The current user s library may be viewed from the My Library tab in the center zone pictured below MusicGroup cf xf Subscribers Online My Library I GroupLibrary Search Transfers Private Messages Group Messages user 1 user3 Album Artist user2 how s it going user2 clap your hands say yeah clap your hands say yeah clap your hands a clap your hands say yeah clap your hands say yeah let the cool god user2 indeed my good sir clap your hands say yeah clap your hands say yeah over and over a clap your hands say yeah clap your hands say yeah sunshine and user3 test clap your hands say yeah clap your hands say yeah details of the w clap your hands say yeah clap your hands say yeah the skin of my user3 this application rocks clap your hands say yeah clap your hands say yeah is this love clap your hands say yeah clap your hands say yeah heavy metal user2 this is a test of a very long clap your hands say yeah clap your hands say yeah blue turning gr message and such oh yeah clap your hands say yeah clap your hands say yeah in this home o Providers Onine clap your hands say yeah clap your hands sayyeah gimme some user3 explosions in the sky is clearly P clap your hands say yeah clap your hands say yeah upon this tidal the best band ever user 1
50. his tier ApplicationManager Class 4 Fields Methods ZCC CCC CCC CC CC CC CCC CC CC C C addGroupEventListener void addProviderEventListener void addSubscriberEventListener void getAllProviderLibraries HashMap String SongCollection gt getMyLibrary SongCollection getProviderLibrary SongCollection getProvidersOnline Set Algorithm WalletCertificate gt getSubscribersOnline Set AlgorithmWalletCertificate gt initialize ApplicationManager removeGroupEventListener void removeProviderEventListener void removeSubscriberEventListener void requestDownload void searchAllByAlbum HashMap String SongCollection gt searchAllByArtist HashMap String SongCollection gt searchAIlByTitle HashMap String SongCollection gt searchByAlbum SongCollection searchByArtist SongCollection searchByTitle SongCollection sendGroupMessage void sendPrivateMessage void start void statusMessage void stop void security Manager Fig 14 Application Manager Tier GroupSecurityManager A Class Fields E Methods Q addUserPublicKeySecurityContext PublicKeySecurityContext Q getGroupPublicKeySecurityContext PublicKeySecurityContext Q getGroupSymmetricKeySecurityContext FixedHelixSecurityContext Q getKeyRefreshInterval long Q getMyCertificate AlgorithmWalletCertificate 9 getMyPublicKeySecu
51. ic key system complete the next step was to define the infrastructure necessary for creating distributing and using those algorithms for secure group communication Both the certificate and certificate authority were designed to be flexible and accommodate any type of public key encryption and signature algorithms Below is a high level design of the certificate authority and certificates added to the TupleBoard library in package edu rit tb security cert D Serializable i StreamSerializable OF Abstract Class f Methods 9 fromStream T toStream void R L m CertificateAuthority ID Certificate 4 Class Class gt StreamSerializable gt StreamSerializable T 7 zi Methods Methods createAlgorithmWalletCertificate void getCAName String getBitStrength int getCASignature byte getCaName String getCASignatureVerificationAlgorithm SignatureAlgorithm y y getCASignatureVerifier SignatureAlgorithm getID String v Ka signi byte d i boolean sign voi AlgorithmWalletCertificate gt 5 Algorithm Wallet Class Class 7b StreamSerializable x 7b Certificate 7 lt algwalet E Methods F Methods createPublicWallet AlgorithmWallet Q getliserEncryptionAlgorithm PublicKeyAlgorithm getGroupEncryptionAlgorithm PublicKeyAlgorithm getLlserSignatureVerificationAlgorithm Sig
52. ic message from userl this is a public message To send a private message use the pm command gt pm user2 this is a private message to user2 gt That command would cause the following system message to appear on user2 s console Private message from userl this is a private message to user2 Downloading Songs No file sharing application would be a file sharing application without the ability to download songs Once a song has been found through either the list or search commands it may be downloaded by using the download command 48 gt download user2 mono yearning tmp downloads mono yearning mp3 gt Note the use of quotes to enclose the song to be downloaded and the path to which the resulting file will be saved These are required for the command to succeed The above command will initiate a download request with the specified provider for the specified song Provider user2 will receive the following system message Subscriber user1 requesting download of mono yearning The following system messages will be displayed on subscriber userl s console Download started mono yearning Download completed tmp downloads mono yearning mp3 The above exchange assumes that subscriber user1 is authorized to download the song mono yearning and that provider user2 is authorized to provide it If either of these are not the case error messages will be received instead Quitti
53. icates using the music collection created in the previous step and the certificate authority created a few steps back MausicAuthorizationCertificates for both roles are created in the following manner 42 gt java edu rit tb music cert MusicCertificateAuthority role lt caFile gt lt startDate gt endDate id musicCollectionFile lt ouputCertFile gt Note denotes a line continuation there should be no newlines in the argument list Argument descriptions lt role gt The role granted by this certificate Must be one of provider or subscriber caFile The file in which the serialized contents of the CertificateAuthority ate stored lt startDate gt The date this certificate becomes valid Format mm dd yyyy lt endDate gt The date this certificate expires Format mm dd yyyy id The ID of the user of device for which the certificate is being generated This must match the ID contained in the user s A gorithmW alletCertificate musicCollectionFile The file in which the serialized contents of the MusicCollection object created in the last step are stored lt outputCertFile gt The file to which the resulting MusicAuthorizationCertificate object will be serialized for persistent storage The program will deserialize the specified CA and music collection objects from disk and then create and sign a new MusicAuthorizationCertificate for the specified role The certifi
54. im explores the use of and improves two Group Diffie Hellman schemes Authenticated Group Diffie Hellman A GDH and Strong Authenticated Group Diffie Hellman SA GDH Through timing measurements Kim concludes that for small groups these protocols may suffice but any system designed to support groups larger than 20 30 nodes will not be able to use them due to the rapid growth of key exchange time as nodes are added In addition to the initial key exchange keys should also be refreshed periodically If forward and backward secrecy is of concern a refresh must also be performed each time the group membership changes The sporadic nature of ad hoc group activity creates an environment in which keys must be refreshed quite often It is therefore even more important that exchanges be performed as quickly as possible There also exist tree based key management schemes which build on the concepts presented but also attempt to minimize the cost of key exchanges and refreshes by aggregating all refreshes in a specific time window into one or limiting the scope of the refresh to subgroups 9 Examples of these protocols include Tree based Group Diffie Hellman TGDH Block Free Tree based Group Diffie Hellman BF TGDH and Distributed Scalable Secure Communication DISEC In a PKI based system such as the one developed for this project group symmetric key exchange is trivial Since the group private key is contained in each user certificate group sy
55. ing process will perform one read print the timing results to standard out and then exit All results were gathered running the posting process on newyork and the reading process on georgia two machines on the CS network at RIT Both machines contained one 650MHz SparcV9 processor and 512MB of ram and were running Solaris 10 at the time of testing The machines were connected via a 100 Mbps Ethernet link Three different files were transferred in this experiment File 1 11 the american analog set aaron and maria mp3 3 045 376 bytes File 2 04 explosions in the sky memotial mp3 12 775 424 bytes File 3 03 mono yearning mp3 23 527 424 bytes Each song was transferred 100 times throughout the day at each security level none auth full in order to obtain these results 33 Raw Transfer Time This test was performed as a baseline with which to compare results of adding security features to the transfer Here the song data is transferred in the clear and no authentication is performed by the reading process File 1 File 2 File 3 Mean Transfer Time msec 2959 19 3840 89 4770 88 Fig 17 Mean Raw Transfer Times Raw Transfer 6000 5000 4000 y 9E 05x 2697 3 3000 R 0 9958 2000 Time Milliseconds 1000 0 5000000 10000000 15000000 20000000 25000000 File Size Bytes Fig 18 Raw Transfer Time 34 Signature Verifi
56. instance of Tup eBoard being used a queue of event listeners to notify of manager events and a collection of tuples that have been posted The methods pos Tuple and withdrawTuples provide an easy way to track and remove tuples from the board for all managers In addition it provides an zsAuthentic method which verifies signatures on tuples received from listeners Since each manager is associated with a particular type of event listener from the model generic addListener and removel istener methods are provided for modifying the listener queue for each manager Within the tier there are two different types of managers The first type includes the GroupParticipationManager which provides functionality common to all group users The second type is the Ro eParticipationManagers of which there are two concrete implementations one for subscribers and one for providers These managers respond to role specific actions and events The GroupParticipationManager is the heavyweight of the tier This manager controls the secure messaging protocol the key exchange protocol and the user announcement protocol 27 The ability to send messages is provided through the sendGroupMessage and sendPrivateMessage methods The key exchange protocol is executed behind the scenes without any interaction although the application is notified through the event model when key refreshes occur Similarly user announcements ate posted automatically when the
57. int g signer PublicKeylgorithm T gt E Methods Q createVerificationdlgorithm SignatureAlgorithn getAlgorithmType SignatureAlgorithms getBitStrength int w getOneWayHash OneWayHash isPrivate boolean sign byte 1 overload w signObject byte w verifyO boolean 1 overload verifyObject boolean Wet N w publicKeySigner RSADoubleSHA256Signature G RSA s Class Class SignatureAlgorithm PublickeyAlgorithn T T Methods il Fields Q createVerificationAlgorithm SignatureAlgorithm E Methods 2 getOneWayHash OneWayHash createEncryptionAlgarithm RSA L sign byte w createPublicInstance RSA 79 verify boolean y createSignatureAlgorithm RSA decrypt BigInteger Q encrypt BigInteger 3 generatePrime BigInteger 9 generateRandomPlaintext BigInteger Q getModulus BigInteger Q getPrivateExponent BigInteger Q getPublicExponent BigInteger Q isPrivate boolean Fig 2 Public Key Algorithms I created a factory class PKLA orithmFactory to specify the available algorithms and simplify the creation of instances of the algorithms in the edu rit crypto pki package In addition I created abstract base classes for both public key encryption algorithms and digital signature algorithms Class PublicKeyAlgorithm defines data members common to any algorithm such as the bit strength and provides an inter
58. is a certificate authority In the TupleBoard API this is represented by class edu rit tb security cert Certificate Authority This class comes equipped with a main method which enables creation of a CA and generation of certificates for distribution to devices Create a Certificate Authority Before any certificates may be generated a static CA must first be created The CA must be persistent across usage sessions because the signatures on all certificates must be verifiable by any device in the group regardless of when its certificate was generated A certificate authority may be created by invoking the following command gt java edu rit tb security cert CertificateAuthority create lt caName gt signatureAlgorithm encryptionAlgorithm lt bitStrength gt lt caFile gt Note denotes a line continuation there should be no newlines in the argument list Argument descriptions lt caName gt The name of the certificate authority This should be unique as this name is also used internally as the group identifier during secure communication lt signatureAlgorithm gt The name of the signature algorithm to use when signing certificates The value of this parameter must be able to be parsed as an instance of the edu rit tb pki PKLAleorithm Factory SignatureA lgorithms enumeration Currently supported values RSAWithDoubleSHA256 lt encryptionAlgorithm gt The name of the encryption algorithm to be used for grou
59. istribution application utilizing the new secure tuple board In this system role based certificates would govern access to and permissions within music groups within the application The system must be resistant to piracy by only permitting song downloads from authorized providers to authorized subscribers In addition all communication must be encrypted to prevent unauthenticated users from gaining access to the secure group or any data transferred between usets Song Metadata The first step in developing the application was to define a set of metadata classes to represent music files MusicCollection GL Class T E Methods contains boolean fromTextFiles MusicCollection toTextFiles void a songs O a abums O Q9 artists B fate d alll x a i E SongCollection D AlbumCollection e ArtistCollection G Class Class Class 7 7 7 zi Fields amp Fields Fields a songs List lt SongInfo gt a albums List AlbumInfo aP artists List String S Methods Methods E Methods add void contains boolean contains boolean w addAIl SongCollection FromFile AlbumCollection fromFile ArtistCollection contains boolean iterator Iterator lt AlbumInfo gt w iterator Iterator String Q fromFile SonaCollection toFile void 9 toFile void get SongInfo getByName SongInfo iterator Iterator SongInfo searchB
60. itStrength helixRand Create the new CA CertificateAuthority c new CertificateAuthority caName groupEncryption signer Serialize the CA to disk for later retrieval c toStream new FileOutputStream caFile Fig 40 Creating a CA With a CA defined it may now be used to generate a certificate for a user This next example displays the creation of an AlgorithmW allet and an AlgorithmW alletCertificate allowing the user to digitally sign messages and participate in secure communications Specify user name String userName userl Specify start date of now Calendar now Calendar getInstance Date startDate now getTime Specify end date of a year from now now add Calendar YEAR 1 Date endDate now getTime 61 Specify file to store private wallet File walletFile new File userl wallet Specify file to store certificate File certFile new File userl cert Load the CA from disk CertificateAuthority c CertificateAuthority fromStream new FileInputStream caFile Create the wallet and certificate c createAlgorithmWalletCertificate startDate endDate username certFile walletFile Fig 41 Creating a Certificate Working with Secure TupleBoard The previous examples give insight into creation and use of some of the security primitives added to the API To show how all of these features interact the final example demonstrates the design o
61. lass Class d l Security Context E Methods a 7 9 forId SecurityContext amp Fields Q getId SecurityContextId j g pka PublickeyAlgorithm Q getinputStream InputStream a rand HelixRandom Q getOutputsStream OutputStre zi Methods f Q getInputStream InputStream Q getOutputStream OutputStream pkinput pkoutput PublicKeyInputStream D PublicKeyOutputStream Class Class gt InputStream OutputStream T 7 E Methods Methods Q available int Q cosel void Q closet void Q Flush void 9 read int 2 overloads 9 PublicKeyOutputStream Q skipi long Q write void 2 overloads helixInput helixOutput HelixInputStream D HelixOutputStream D Class Class gt InputStream gt OutputStream r T E Methods E Methods Q available int Q close void Q close void Q Flush void Q getBuffer ByteBuffer Q getBuffer ByteBuffer Q getChannel ReadableByteChannel Q getChannel WritableByteChannel Q getMonce HelixNonce Q getNonce HelixMonce Q read int 2 overloads Q writeQ void 2 overloads Q skipi long Fig 5 Public Key Security Context 14 A public key security context is initialized with a public key algorithm capable of encrypting data able to be decrypted only by the target user s and a PRNG to be used for generating a symmetric data transfer key The getlnputStream and gefOutputStream
62. load each role s song collection metadata and join the group 50 System Messages As the graphical client is being used various system messages will be displayed in the status bar atea at the bottom of the main window Examples of system messages include provider and subscriber online and offline notifications download requests group key exchange information and incoming private and group messages Who s Online A good place to start when using the application is to see what other subscribers and providers are online While system messages ate generated each time a new user enters or leaves the group the current group members are also shown in the left zone Current subscribers appear in the top list labeled Subscribers Online Similarly current providers appear in the bottom list labeled Providers Online MusicGroup Subscribers Online user1 user3 user2 Providers Online user1 user2 Group Library Search Transfers Private Messages Group Messages Album Artist clap your hands say yeah clap your hands say yeah clap your hands gt clap your hands say yeah clap your hands say yeah let the cool god clap your hands say yeah clap your hands say yeah over and over a clap your hands say yeah clap your hands say yeah sunshine and clap your hands say yeah clap your hands say yeah details of the w clap your hands say yeah clap you
63. manager starts The remaining two managers ProviderPartiapationManager and SubscriberParticipationManager implement the song transfer protocol Class ProviderParticipationManager manages the operations reserved for those users with the provider role namely transferring songs to subscribers Similarly class SubscriberParticipationManager manages the operations reserved for those users with the subscriber role namely downloading songs from providers As mentioned previously the manager classes of this tier relay events received from their enclosed listeners to the rest of the application through a custom event model Below is the design of the event listener interfaces which make up this model MusicEventListener Y Interface KeyEventListener D GroupEventListener Interface Interface MusicEventListener MusicEventListener Methods Methods Q groupKeyRefreshComplete void Q privateMessageReceivedt void O groupKeyRefresh5tarting void providerOffline void Q providerOnline void Q public MezsageReceivedy void Q statusMessage void Q subschberOfflne void 9 subscberOnlne void SubscriberEventListener Interface MusicEventListener ProviderEventListener Interface MusicEventListener Methods zi Methods Q downloadReguested romSubscriber void Q downloadComplete void A 9 downladError void Q downladstarted void
64. mmetric keys may be posted encrypted with the group public key In addition the authentication of group members and keys is provided via digital signatures on each message exchanged Key refreshes are performed in the same manner as the initial key exchange by posting a new encrypted symmetric key Details of how these protocols are implemented appear in the next section SecureTupleBoard API Design amp Implementation Secure TupleBoard API Design amp Implementation When this project was started the TupleBoard API included only limited security Package edu rit crypto hash provides support for two hashing algorithms SHA 256 and Double SHA 256 as well as an abstract OneWayHash base class for extensibility Symmetric key encryption is supported by package edu rit crypto helix which contains an implementation of the Helix stream cipher 3 Tuples could be securely transferred over the network through the FzxedHelixSecurityContext found in package edu rit tb security which is backed by this cipher however the symmetric key had to be agreed upon offline prior to the transfer The remainder of this section describes the security additions made to the library namely secure pseudorandom number generation public key cryptography and digital signatures Generating Randomness A vital part of any cryptographic library is the ability to generate random data Here the term random is used as a generalization Truly random data is often hard to
65. n uploaded or downloaded during the current session The log is accessible through the fourth tab in the center zone labeled Transfers 55 Z MusicGroup f xj Subscribers Online MyLibrary GroupLibrary Search Transfers Private Messages Group Messages user1 user3 Downloads user2 how s it going user2 Album Artist Title the earth is nota cold dead place explosions in the sky your hand in mine user2 indeed my good sir you are there mono moonlight know by heart the american analog set aaron and maria user3 test user3 this application rocks user2 this is a test of a very long 4 D message and such oh yeah EA user3 explosions in the sky is clearly Providers Onine eue Uploads ithe best band ever user1 Album Artist Title User user2 the earth is not a cold dead place explosions in the sky memorial user2 user2 yes indeed my good sir i also you are there mono yearning user2 enjoy mono you are there mona yearning user2 4 ll Download of explosions in the sky memorial requested by user2 Fig 33 Song Transfer Log Transactions are broken down into downloads and uploads Each list contains an entry for each song transferred and the user at the other end of the exchange Note that if the current user does not have the subsctiber role enabled the download log will
66. natureAlgorithm 9 getliserEncryptionAlgorithm PublicKeyAlgorithm getUserSignatureAlgorithm SignatureAlgorithm create T isPrivate boolean Fig 4 Public Key Infrastructure 12 The Certificate base class seen above contains the data fields and behavior common to any type of certificate based system Each certificate contains the ID of the user or device for which it was generated and the name of the CA with generated it Each certificate also has a start date and an end date between which it is considered to be valid The most important feature of the base certificate is its signature and the inclusion of a SzgnatureAlgorithm capable of vetifying this signature Through these the integrity of the certificate can be vetified and the ID of its presenter confirmed authentic A certificate is accepted as valid if the CA s verification algorithm matches the well known verification algorithm for the group its signature verifies correctly using that algorithm and the current date is after the start date but still before the end date While this simple certificate may be sufficient for very basic identification purposes it does not give the possessor the ability to receive encrypted messages or send signed messages in TB Class AlgorithmW alletCertificate extends the base Certificate class and adds fields for a public key encryption algorithm and a signature algorithm for precisely this reason Internally the certificate
67. ner s Formula z a D qInrp mod p q b to recombine the modular parts and retrieve 4 Timing measurements during implementation showed this CRT based implementation to be 2 to 3 times faster than the naive approach For additional information on generating instances of RSA and its use for encrypting data 8 g rypting please see the Developer s Guide found later in this document RSAWithDoubleSHA256 Once the implementation of RSA completed it was then possible to create a digital signature algorithm based upon it Digital signatures offer two main benefits First they provide an authentication mechanism If a message signature verifies correctly it confirms the identity of the sender of the message Since only the sender would have known the private key used in signing the signature must have been sent by the expected source Second they provide an integrity check on the contents of the message itself Since the contents of the message are hashed during signing any tampering or loss of data during transmission will cause the verification to fail If the message signature verifies correctly it confirms that the message itself is intact Class RS ADoublSHA256 Signature represents a concrete instance of class SzgnatureAlgorithm Like the name suggests the algorithm pairs an instance of RSA with an instance of DoubleSHA256Hash Class SignatureAlorithm provides two methods for computing signatures The first sgzi takes any OneWayHash as i
68. ng the Application When finished interacting with the music group simply use the quit command gt quit oe gt All tuple board interactions will be immediately ceased and the application will shutdown returning to the shell from which it was started 49 Join a Music Group Graphical Client This section describes how to use the Swing based graphical Music Group client The syntax of this program is identical to that of the command line version gt java edu rit tb music MusicGroupGUI userID lt groupID gt lt certDir gt provider musicLibDir subscriber lt musichibDir gt Note V denotes a line continuation there should be no newlines in the argument list gu Argument descriptions All arguments are identical to those for the command line client Please see the previous section for descriptions on the arguments required for the application Example gt java edu rit tb music MusicGroupGUI userl groupOne data provider music subscriber music MusicGroup Subscribers Online My Library Group Library Search Transfers Private Messages Group Messages Providers Online Reading existing group data Fig 27 MusicGroup Graphical Client The graphical client will perform all the same steps as the command line client on startup desetialize the user s certificate and wallet files enable the specified role s
69. nput and generates a signature as a byte array based on the output of the hash function The second signOlject is a convenience method and takes any Serializable object This overload simply serializes the object and writes its contents to the OneWayHash specified by the concrete class and then calls the s gu method to finish the computation Similarly there are also two methods for verifying signatures These function in exactly the same way as the signing methods The first verify takes a OneWayHash and the signature as a byte array and returns the result of the verification as a boolean The second verifyOlyect is a convenience method and takes any Serializable object This overload simply serializes the object and writes its contents to the OneWayHash specified by the concrete class and then calls the first ernt method to finish the computation The diagram on the following page details the steps involved in generating a signature for a message to be sent and verifying that signature when the message is received Once again the implementation for this algorithm comes from Practical Cryptography 2 10 Signer Message Verifier SignatureAlgorithm SignatureAlgorithm Kas gt Kas Kes Message Message OneWayHash OneWayHash Seed s Message Seed HelixRandom HelixRandom Random Random d Equals r r LLL r ES es SPd y
70. ntListener ProviderEventListener SubscriberEventListener lt Tuple gt lt Tuple gt lt Tuple gt lt Tuple gt ae A CLE eu RU Yee d SS RR Oe SS x a mor E v Tuple Board EA S EN NE ences Lat tae se a EE v EN u r aa Fig 11 Application Architecture The bottom tier consists of instances of TupleListeners which are added to the tuple board during application initialization These listeners mentioned in the protocols section above notify the participation manager tier of the posting and withdrawing of protocol tuples The participation manager tier responds to events from the listener tier and provides abstraction from the tuple board for the application manager tier when executing application protocols such as messaging It also passes notifications of protocol activity up to the application tier through a custom event model The application tier passes actions from the view tier to the participation manager tier and also passes events received from the participation managers to the view Each of these tiers is discussed in detail next 25 Listener Tier The listener tier is responsible for monitoring the tuple board and notifying the participation manager tier when tuples are posted and withdrawn The implementation of this tier deviates slightly from the architectural diagram in that the listeners are actually implemented as anonymous inner classes contained within the participation manager tier Seven different listene
71. odulus This conversion is known as a padding scheme Remember that RSA should not be used for bulk encryption operations but instead for exchanging the key for the symmetric algorithm that will do the bulk encryption Create the plaintext message BigInteger plaintext new BigInteger 1234567890 Encrypt the message BigInteger ciphertext rsa encrypt plaintext Decrypt the message BigInteger decrypted rsa decrypt ciphertext Verify the operation was a success if plaintext equals decrypted System out println Success Fig 37 Encryption and Decryption using RSA 59 Wotking with Digital Signatures Currently the TupleBoard library supports one signature algorithm RSADoubleSHA256Signature Instances of the algorithm may be obtained through the provided algorithm factory class PKLA gorithmFactory The factory automatically generates the necessary keys according to the bit strength specified While any number of bits may be used a value of 2048 is tecommended as a minimum to achieve a reasonable level of secutity Specify the bit strength of the algorithm to be created int bitStrength 2048 Obtain an instance of RSADoubleSHA256Signature SignatureAlgorithm rsaSignature PKIAlgorithmFactory createEncryptionAlgorithm SignatureAlgorithms RSAWithDoubleSHA256 bitStrength helixRand Fig 38 Obtaining an instance of RSADoubleSFLA256Sgnature Once an instance
72. of the signature algorithm has been obtained it may be used to compute signatures t is often desired to sign an object such as a tuple or a certificate The following example demonstrates this signing process Object to sign Serializable toSign new SomeObject Sign object byte signature rsaSignature signObject toSign Nerify signature boolean verified rsaSignature verifyObject toSign signature Nerify the operation was a success if verified System out println Success Fig 39 Creating and Verifying a Digital Signature 60 Wotking with Certificates In order to use the public key algorithms and signature algorithms shown in the examples above in a group setting there must be a way to distribute user algorithm data In the TupleBoard library this is done through a certificate The process begins by creating a certificate authority Specify the CA s name This can be used as a group identifier String caName myCA Specify the file in which the CA will persist File caFile new File myCA ca Create a CA Signature Algorithm for signing certificates SignatureAlgorithm rsaSignature PKIAlgorithmFactory createEncryptionAlgorithm SignatureAlgorithms RSAWithDoubleSHA256 bitStrength helixRand Create a public key algorithm to enable groupwide communication PublicKeyAlgorithm rsa PKIAlgorithmFactory createEncryptionAlgorithm EncryptionAlgorithms RSA b
73. omBytes void Q encryptMext int Q isSeeded boolean Q erase void Q nextBytes void 1 overload Q mac int Q setSeed void Q main void j Q next int Q packi int 1 overload Q setKey void Q startKeystream void Q startMact void Q unpack void 1 overload Fig 1 A eryptograpbically strong PRNG based on the Helix stream cipher The concept for this algorithm was derived by modifying an algorithm found in Practical Cryptography 2 for creating a PRNG using a block cipher such as AES When the PRNG is seeded it initializes a new instance of Helix using the specified seed Random data is then retrieved through the zexzByres method which simply encrypts the value 0 to obtain the XOR of the random key stream The class is used throughout the TupleBoard library and is mentioned multiple times in this section Guidelines for its use may be found in the Developer s Guide found later in this document Public Key Algorithms In order to have a public key infrastructure it is first necessary to have public key algorithms to back it The primary difference of public key encryption algorithms from their symmetric key counterparts such as Helix is that the encryption and decryption keys are different Also the security of these algorithms is based on intractable computational problems such as factoring large numbers or solving discrete logarithms Encrypting and decrypting data using a publi
74. or any incoming song transfers using a SongTransfer uple template initialized with the user s AlgorithmW alletCertificate as the target field Similarly the provider listener is only enabled if the current user is authorized as a provider This listener listens for any incoming download requests using a DownloadRequestl uple template initialized with the user s AlgorithmW alletCertificate as the providerCert field These listeners are contained with in role participation managers the SwbscriberParticipationManager and ProviderParticipationManger respectively Participation Manager Tier The next application tier is the participation manager tier In addition to containing the listener tier this tier provides abstraction from the tuple board to the rest of the application Notifications received from listeners are relayed through an event model to the application tier In the opposite direction actions requested in the application tier are delegated to this tier and translated into the necessary tuple protocol actions Below are the classes that make up this tier 26 RoleParticipation anager Abstract Class gt ParticipationManager N ParticipationManager 31 7 Abstract Class E Fields 7 g certificates List lt MusicAuthorizationCertificate gt lt Fields 39 musicLibrary SongCollection 3 board TupleBoard g role MusicGroupRoles 9 eventListeners List lt L gt E Methods 3 postedTuples HashMap lt 14
75. p The value of this parameter must be able to be parsed as an instance of the edu rit tb pki PKLAleorithm Factory SignatureAlgorithms enumeration Currently supported values RSA 39 lt bitStrength gt The bit strength of the algorithms For the RSA encryption and signature algorithms this is the bit size of the public modulus n For RSA based algorithms this argument should be gt 2048 lt caFile gt The file to which the resulting CertificateAuthority object will be serialized for persistent storage The program will generate the public private key pairs required for the signature and encryption algorithms and then serialize the resulting CertuficateAuthority object to disk at the location specified Generation of a 2048 bit RSA RSAWithDoubleSHA256 certificate authority generally takes 8 10 minutes on a 650MHz SparcV9 CPU or 1 minute on a 1 8GHz Pentium M CPU Example 2 java edu rit tb security cert CertificateAuthority create groupOne RSAWithDoubleSHA256 RSA 2048 groupOne ca Creating CA signature public private key pair Creating group encryption public private key pair Writing CA to home stu9 s15 krm4686 courses msproj data groupOne ca oe gt Generate a Certificate Once a certificate authority has been created device certificates may begin to be generated In order to participate in secure group communication a device must have a valid certificate from the group CA Device certificates are represen
76. pE xistenceTuple When a user creates a new tuple board a read is performed for any existing tuples of this type If the read succeeds the returned GroupExistenceluple contains the current group symmetric key and the user may initialize an instance of FixedHelxSecurityContext using the read key If no tuple is currently available meaning the user is the first one to join a new GroupExistenceTuple is created with a randomly generated key This tuple is then posted to the board using a new PublicKeySecurityContext initialized with the group public key encryption algorithm and an ID of GroupSymmetricContext concatenated with the contents of the amp eyID field in the tuple This additional ID field is included to prevent accidental reuse of an old security context identifier The protocol also allows for periodic refreshes of the group symmetric key This feature is to prevent attacks which can arise when keys are used too many times The frequency with which the key is refreshed is controlled by the system property b keyrefresh interval specified in milliseconds The default value is 900000 or 15 minutes A key refresh is performed the same way as the initial key generation The original poster of the GroupExistencel uple withdraws the old tuple generates a new random key and reposts a new tuple Meanwhile all other group users are listening for tuples of this type and are notified of its posting and refresh their respective symmetric s
77. r hands sayyeah the skin of my clap your hands say yeah clap your hands say yeah is this love clap your hands say yeah clap your hands say yeah heavy metal clap your hands say yeah clap your hands say yeah blue turning gr clap your hands say yeah clap your hands say yeah in this home o clap your hands say yeah clap your hands say yeah gimme some clap your hands say yeah clap your hands say yeah upon this tidal the earth is not a cold dead place explosions in the sky first breath afte the earth is not a cold dead place explosions in the sky the only mome the earth is not a cold dead place explosions in the sky Six days atthe the earth is not a cold dead place explosions in the sky memarial the earth is not a cold dead place explosions in the sky your hand in m you are there mona the flames bey you are there mono a heart has as you are there mono yearning you are there mono are you there Imana lthe remains nfi I ji user2 how s it going user2 indeed my good sir user3 test user3 this application racks user2 this is a test of a very long message and such oh yeah user3 explosions in the sky is clearly Ihe best band ever user2 ves indeed my good sir i also enjoy mono New group message received from user2 Fig 28 Current users online appear in t
78. r online userl gt Creating new group The application is now fully initialized and ready to process user commands System Messages As the command line client is being used various system messages will be displayed to the console All system messages ate contained within square brackets like this system message Examples of system messages include provider and subscriber online and offline notifications download requests group key exchange information and incoming private and group messages Available Commands The list of commands the application responds to may be accessed by typing help help Available commands download provider lt artist title gt lt path gt gm lt message gt help list all my providerID online providers subscribers pm id message quit search all providerID gt lt artist album title gt lt string gt 45 Download the specified song Send a message to all group Print this menu View available song library View users currently online Send a message to user id Quit the application Search function users Who s Online A good place to start when using the application is to see what other subscribers and providers are online While system messages are generated each time a new user enters or leaves the group it is sometimes convenient to get the list of all currently participating usets To do so
79. regulated through roles and transfer permissions a new certificate authority and certificate had to be created to associate these permissions with users Class MusicAuthorizationCertificate handles the binding of a role and a catalog of authorized music to a user For a provider certificate the catalog specifies the songs the provider may distribute Similarly in a subscriber certificate it specifies the songs the subscriber may request for download Class MusicCertificateAuthority enables generation of these new certificates This certificate authority is analogous to a record label permitting distribution of songs on a per user basis The certificate is like a user license to provide or obtain songs Below is a design diagram of these new classes 19 G MusicCertificateAuthority Class s E Fields d certAuthority CertificateAuthority d dateFormatter SimpleDateFormat E Methods Q createCertificate MusicAuthorizationCertificate createCertificate gt MusicAuthorizationCertificate Class T Certificate Methods Q getRole MusicGroupRoles 9 isAuthorized boolean loadCertificatesFromDisk List MusicAuthorizationCertificate gt Nested Types C MusicGroupRoles Enum Provider Subscriber collection MusicCollection Class Fig 9 Music Authorization Framework Each MasicAuthorizatinCertificate contains authorizations for one role and one MusicCollection
80. rityContext PublicKeySecurityContext Q getMyWallet AlgorithmWallet Q getPRNG HelixRandom getUserPublicKeySecurityContext PublicKeySecurity Context Q initialize GroupSecurityManager Q instance GroupSecurity Manager Q setGroupSymmetricKeySecurityContext void Class GroupSecurityManager is implemented as a singleton and serves as a container for all security related processes in the application This class holds a PRNG and the user s private algorithm wallet and public certificate as well as numerous security contexts In addition to the group and user PublicKeySecurityContexts it also maps users to their respective PublicKeySecurityContext for easy lookup when communicating solely with a single user 29 Class ApplicationManager servers as the main controller between the view and manager tiers This class initializes all necessary participation managers when started and relays all events generated by them up to the view The view may register listeners through the provided add Listener methods In addition it provides methods for initiating all of the protocols supported by the system through the view This class also represents a single point of storage for current group data Current collections of the subscribers and providers currently online are maintained as well as the available music libraries available by each provider and the application user The manager also exposes music library search functionality brok
81. rs are supported The first is a PostLstener which listens for GroupExistenceTuples The template tuple used is simply a blank GroupExistenceTuple When matching tuples are posted this listener notifies its associated participation manager to initiate a key refresh The next two listeners are PostWithdrawListeners and perform the reading portion of the user announcement protocol described earlier The subscriber listener uses a blank Subscriber Tuple in order be notified when any subscribers come online or go offline Similarly the provider listener uses a blank ProwiderTuple in order to be notified when any providers come online or go offline In order to implement the messaging protocol two additional PostLzsteners are defined The group message listener listens for incoming group messages using a blank GroupMessageTuple template The private message listener listens for incoming private messages using a PrivateMessageTuple template initialized with the user s A gorithmW alletCertificate as the fo field All of the listeners defined so far are contained within the GroupParticipationManager a part of the participation manager tier responsible for all general group protocol activities The remaining two listeners are unique for each role for which the application user is authorized Together they implement the song transfer protocol The subscriber listener is only enabled if the current user is authorized as a subscriber This listener listens f
82. ructure PKI provides a framework for establishing and authenticating secure communication between devices A trusted certificate authority CA generates an identifying token or certificate for an authorized device The certificate contains the device s public key and other identifying information and is digitally signed by the CA to prevent forging This public key may be used to initiate secure communication with a device In addition any devices not possessing a valid certificate will be denied from communicating with the rest of the ad hoc group PKI is often used in traditional client server architectures a browser establishing an SSL session with a secure web server for example This project migrates the concepts of PKI to the ad hoc arena This project uses the tuple space distributed computing paradigm for all ad hoc group communication A tuple space is a store of tuples or lists of objects from which consumers may read tuples matching filter criteria and to which producers may post new tuples 4 An easily made physical analogy to this concept is that of an announcement board where people may read flyers and post new ones While several implementations of tuple spaces in Java exist IBM s TSpaces 5 for example they employ a client server architecture which is incompatible with the ad hoc network setting for this project Professor Kaminsky s TupleBoard API 7 is an implementation of tuple space designed for developing ad ho
83. s extend class SzenedTupk meaning all instances are digitally signed at creation before being posted and verified when read Any tuples unable to be correctly verified are ignored SignedTuple Class gt Tuple E Methods Q getCertificate AlgorithmWalletCertificate Q getSignature byte Q isAuthentic boolean E verify CASignature boolean E verifyUserSignature boolean PrivateMessageTuple 5 GroupMessageTuple D Class Class SignedTuple SignedTuple 7 7 E Fields 2 Fields from AlgorithmWalletCertificate message String Y sequenceNumber long E Methods Q create GroupMessageTuple from AlgorithmWalletCertificate message String Y sequenceNumber long to AlgorithmWalletCertificate E Methods 9 create PrivateMessageTuple SongTransferTuple 5 DownloadRequestTuple A Class Class gt SignedTuple SignedTuple r T 2i Fields Iz Fields 4 song SongInfo providerCert AlgorithmWalletCertificate target AlgorithmWalletCertificate song SongInfo Methods E Methods Q create SongTransferTuple Q create DownloadRequestTuple Q getMP3File File 9 is uthorized boolean isAuthorized boolean N GroupExistenceTuple ProviderTuple A SubscriberTuple A Class Class Class SignedTuple SignedTuple SignedTuple 7 T 7 E Methods I Fields E Fields Q create GroupExist
84. sages between users in the group through the secure messaging protocol Two types of messages are supported The first is a group message This type of message is able to be read by all users currently participating in the group The second type is a private message This message is only able to be read by the intended recipient The GroupMessageTupl allows for messages to be sent to the entire group It includes matchable fields for the originator of the message the message itself and the sequence number associated with the message These tuples are posted using the group FixedHelixSecurityContext so all other group members may decrypt their contents and successfully read the message Group users are notified of the posting of these tuples through a listener on the tuple board The PrivateMessageTuple is very similar to the GroupMessageTupke but allows for messages to be sent to a single user In addition to the matchable fields of the GroupMessageTupke it also provides a field for the intended recipient These tuples are posted using a PublicKeySecurityContext initialized with the public key encryption algorithm of the recipient Since only this user has the private portion of the algorithm capable of decrypting the message it is unable to be read by anyone but the recipient Group users are also notified of the posting of these tuples through a listener on the tuple board Since group messages are posted using the group symmetric key context when
85. step is to generate two large prime numbers p and g Each prime should be approximately 2 bits in length where is the desired length in bits of the binary representation of z The private method generatePrime handles generation of these primes First an instance of the HelixRandom PRNG generates b 8 random bytes which are then interpreted as a positive BigInteger The resulting number is then verified to not be congruent to 1 modulo e and is tested for primality using the Bzgluteger s isProbablePrime method If both of these conditions are true the number is returned otherwise the method loops until a suitable number has been found Once both p and q have been generated the instance of RSA may be created Public exponents are static in my implementation Instances of RSA destined for use as encryption algorithms use e 3 while those used as signature algorithms use e 5 Public instances are initialized with only the public parameters the encryption exponent e and the modulus n pq This instance is capable of performing encryption only Private instances are initialized with all the parameters e and 7 as specified in the public instance as well as the two primes p and 4 the private exponent d mod p 1 g 1 and qInvP q mod p The last parameter is precomputed to increase efficiency of the decryption computation Rather than computing z mod 7 we can compute a mod p and b mod 4 and then use Gar
86. t the song itself such as the album on which it appears via an Albumlnfo object the track number on that album and obviously the artist and song title This class also has the ability to initialize its data members directly from an mp3 file by reading its ID3 tags and MPEG header data This functionality is provided by the open source Java ID3 Tag Library 1 The SongCollection class represents a collection of songs This class is used widely in the application from parsing local media libraries at startup to informing subscribers of available media from providers Further details on how this is done appear later in this section The remaining collection classes were designed mainly for authorization duties As mentioned previously song transfers in the system are only permitted between authorized users A user is considered authorized to participate in a transfer if a MusicCollection object containing the requested song is associated with that user MusicCollection objects are created and associated with users by a newly created music certificate authority discussed in detail a little later Roles and Authorizations The application currently supports two roles subscriber and provider In addition to the general group activities supported such as sending and receiving public and private messages subscribers are permitted to download songs Providers are allowed to provide songs for download to subscribers In order for group activity to be
87. ted in the API by class AlgorithmW alletCertificate A device certificate may be generated by invoking the following command gt java edu rit tb security cert CertificateAuthority generate lt caFile gt startDate endDate id lt walletCertFile gt lt privateWalletFile gt Note denotes a line continuation there should be no newlines in the argument list Argument descriptions lt caFile gt The file in which the serialized contents of the certificate authority created in the previous step are stored lt startDate gt The date this certificate becomes valid Format mm dd yyyy lt endDate gt The date this certificate expires Format mm dd yyyy 40 id The ID of the user of device for which the certificate is being generated This should be unique within the group lt walletCertFile gt The file to which the resulting 4 eorztbuW alletCertificate object will be serialized for persistent storage lt privateWalletFile gt The file to which the resulting A gorithmW allet object will be serialized for persistent storage The program will deserialize the specified certificate authority and create a new AlgorithmW allet This wallet containing the private group public key encryption algorithm user signature algorithm and user public key encryption algorithm and an Algorithm W alletCertificate created from the public instances of its algorithms are then serialized to disk at the locations
88. ther containing the user s serialized public certificate Finally there needs to be a method of persistent storage for the certificate authority and certificates between application sessions Serialization is a good candidate for this requirement especially since certificates must be serializable to be sent over the network anyway That is why all classes above derive from the common base class edu rit io StreamSerializable This class simply defines convenience methods romStream and toStream for serializing and deserializing these objects to and from streams Please see the Developer s Guide and the User Manual found later in this document for more information regarding creating CA s and generating certificates 13 Public Key Encryption in TB With all the public key infrastructure pieces now in place a new SecurityContext had to be created to support transferring tuples using public key encryption Class PublicKeySecurityContext enables the transfer of a tuple encrypted such that only a user possessing the corresponding private instance of a public key algorithm may decrypt its contents As mentioned earlier public key encryption is not used for bulk encryption operations but is often used to transfer an encrypted symmetric key which the data will actually be encrypted with Below is the design for the new PublicKeySecurityContext SecurityContext 4 PublicKeySecurityContext Abstract C
89. tificate AlgorithmWalletCertificate myCert AlgorithmWalletCertificate fromStream new FileInputStream new File user2 cert Read in user2 s certificate AlgorithmWalletCertificate userOneCert AlgorithmWalletCertificate fromStream new FileInputStream new File userl cert Create the security context with which to read The security context s id is based on my certificate PublicKeySecurityContext pksc new PublicKeySecurityContext new CertificateSecurityContextId myCert myCert getUserEncryptionAlgorithm helixRand Create the tuple board TupleBoard board new TupleBoard Read tuple SecureExampleTuple received board read new SecureExampleTuple Nerify signature and print message if received isAuthentic myCert getCASignatureVerificationAlgorithm System out printin Messag received message Fig 42 Working with Secure TupleBoard 64 Deliverables The following is a list of all deliverables for this project Required Libraries o jid3lib 0 5 4 jar Java ID3 Tag Library o AbsoluteLayout jar Netbeans Swing Absolute Positioning Support e Source Code O tbstrc jat Secure TupleBoard API o musicgroupstc jar MusicGroup Application e Executables o tb jar Secure TupleBoard API o musicgroup jar MusicGroupApplication e Documentation o Secure TupleBoard JavaDoc o MusicGroup Application JavaDoc o Final Repott this document
90. y encrypting r with the receiver s public key K and writes this value onto the stream Meanwhile on the receiving side a new instance of PublicKeyInputStream is created by the receivers corresponding PublicKeySecurityContext object The input stream reads the value x and decrypts it using the private key Ky to obtain z Now that both parties now have the value r the underlying symmetric key algorithm Helix may be initialized The sender and receiver both hash the value rto obtain the symmetric key Kj A new HeZxOutputStream is initialized on the sending side with the symmetric key and a randomly generated nonce N which is transferred first At the same time the receiving side initializes a new HelixKeylnputStream with the same key and reads the nonce value from the stream From this point on all further I O operations are delegated through these objects As an added bonus the Helix algorithm also computes a message authentication code or MAC while encrypting a plaintext When all serialized tuple data has been transferred the HelixOutputS tream writes this code to the stream before closing it The HeZxInpautStream on the other side can then read this code and compare it to its locally computed MAC to verify the authenticity and integrity of the received tuple Digital Signatures in TB In order to support digital signatures in the TupleBoard library a new SzgnedTuple type was created This class extends Tp and so may be used in the same mann
91. yAlbum SongCollection AlbumInfo searchByArtist SongCollection E Albuminfo a searchByTitle SongCollection size int Class r toFile void Fields a albumName String 9 artist String 3 year String SongInfo G Methods C9 Songlnfo 9 Y Class FromAlbumInfoString AlbumInfo T getAlbumName String S Fields getArtist String j album AlbumInfo getYear String 9 bitRate int Q toAlbuminfoString String 9 file File 49 title String 3 trackLength int g trackNumber int E Methods fromSongInfoString SongInfo Q getAlbum AlbumInfo getArtistName String getBitRate int getFile File getTitle String getTrackLengthSeconds int getTrackNumber int toSongInfoString String Fig 8 Metadata Classes 18 The metadata classes can be divided into two categoties entity classes and collection classes Entity classes Songlnfo and A bumlnfo contain useful information about songs and albums respectively The remaining collection classes allow for entity objects to be easily stored iterated over and queried All classes are able to be serialized to disk or over the network The Songlnfo class is the real workhorse of the metadata classes This class contains a great deal of information about an mp3 file including physical format data like bit rate and song length as well as data abou

Secure Ad Hoc Group Communication Using PKI

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