here - Securing Info-Computer Network to Promote an E
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1. Table 1 Security levels and protection periods from ECRYPT EU a pond Protection Comment 1 32 Attacks in real time by Only acceptable for individuals authentication tag size 2 64 Very short term protection Should not be used for against small organizations confidentiality in new systems Short term protection against 3 72 medium organizations medium term protection against small organizations Very short term protection 4 80 against agencies long term Smallest general purpose level protection against small lt 5 years protection organizations 5 112 Medium term protection Approximately 20 years Good generic application 6 128 Long term protection independent recommendation 30 years 7 256 Foreseeable future pod protection against quantum computers For Mobile ECC at security strength of 96 bits its protection period is between the protection periods of 5 years 80 bits and 20 years 112 bits Moore s Law and key strengthening are applied and it has about 20 years of protection period Moore s Law is the empirical observation that the transistor density of integrated circuits with respect to minimum component cost doubles every 24 months It is attributed to Gordon E Moore a co founder of Intel URL http en wikipedia org wiki Moore_Law Key strengthening is explained as below using the password length equation Password length equation S n L R P S Ke2. K1 to get a message to be compared with file F1 9 If the decrypted F2 is different from the F1 Bob rejects Alice s public key file 10 If the decrypted F2 is the same as the F1 Bob accepts Alice s public key file 11 Bob can do the same like Alice to send his public key file to Alice 12 The security of this method is subject to the interception attacks of email and postal mail by hackers and network administrators E 4 Fourth Method Securely Sending Alice s Public Key File to Bob Using Several Serial Introducers 1 Alice establishes a serial path with several nodes representing the introducers from herself to Bob 2 Serial Path Alice Introducer_1 Introducer_2 Introducer_N Bob 3 Alice uses the software of MobileECC Beta version and creates a public key file called F1 by keeping a private key P1 as secret 4 The secret P1 can be copied into a text file or Microsoft Word document and then stored it into a USB flash drive as a token 5 Alice fills in her details into the F1 6 Select all and copy all the text in F1 and paste it into a Microsoft Word document called F2 7 After that Alice encrypts the F2 using the security function at the MS Word tool bar Tools gt Options gt Security by using a symmetric key password K1 8 Then Alice sends F1 and encrypted F2 to Introducer_1 using email 9 Alice sends the key password K1 to Introducer_1 using her mobile phone to I
3. and postal mail by hackers and network administrators Part F Symmetric Key Sharing Scheme Using MePKC MoPKC F 1 A Symmetric Key Encrypting a Plaintext is Shared Using MePKC MoPKC between Two Parties 1 To increase the security level of the MobileECC the ciphertext of MobileECC has to be short and random 2 This is possible if the ciphertext of MobileECC is just a short message of symmetric key 3 Create a symmetric key as K1 can store it into a text file as F1 4 Create your message M1 in the file format of Microsoft Word document and encrypt it as file F2 by using the same symmetric key K1 5 For other data format compression software with encryption function like WinZip can be used During the data compression encrypt the data M1 as file F2 by using the same symmetric key K1 6 Encrypt file F1 using the receiver s public key and MobileECC to create a ciphertext Cl 7 Send the files F2 and C1 to the receiver 8 The receiver recovers symmetric key K1 from file C1 by using receiver s private key 9 Recovered K1 is used by the receiver to decrypt file F2 to get back message M1 10 The receiver can use the same symmetric key K1 to communicate with the sender 11 The security of this method by using a short encrypted symmetric key as the ciphertext of MobileECC is stronger than the computer communications of MobileECC operating on a big message directly Part G OTP One Time Password Scheme Using MePKC Mo
4. be maintained at constant security level Table 2 Fixing at R 1 for slow computer with key strengthening L year n bit L bit R bit P bit 0 05 Is ML bit S bit ECC 2S 5 29 9 27 2 0 19 9 4 3 2 5 83 8 167 6 10 29 9 28 2 0 19 9 4 3 5 87 3 174 6 20 29 9 29 2 0 19 9 4 3 10 93 3 186 6 30 29 9 29 8 0 19 9 4 3 15 98 9 197 8 50 29 9 30 6 0 19 9 4 3 25 109 7 219 4 100 29 9 31 6 0 19 9 4 3 50 135 7 271 4 300 29 9 33 1 0 19 9 4 3 150 231 2 474 4 4 Mobile ECC also has a digital signature system It uses ECDSA Elliptic Curve Digital Signature Algorithm for both signature generation and signature verification Information about ECDSA can be obtained from ANSI American National Standards Institute URL http webstore ansi org USA for the document of ANSI X9 62 2005 Public Key Cryptography for the Financial Services Industry The Elliptic Curve Digital Signature Algorithm ECDSA dated 16 November 2005 Another source is NIST National Institute of Standards and Technology URL http www nist gov USA for the document of FIPS 186 2 with Change Notice 1 dated October 5 2001 announced on 15 February 2000 URL http csrc nist gov cryptval dss htm 5 For public key generation enter the private key into the textbox of Private Key Field 192 bit Private key can be obtained either from the key hash of 2 dimensional key 2D key input method and system mu
5. face to face 2 Alice and Bob exchange their public key file and sign the public key file of opposite party to generate public key certificate 3 Alice and Bob mutually act as introducer Alice is the introducer of Bob and Bob is the introducer of Alice 4 Alice and Bob mutually exchange the signature of the public key file 5 Alice and Bob both obtain their public key certificate consisting of owner s public key file and its signature signed by the introducer 6 Public Key Certificate Public Key File Its Signature File Signed by an Introducer 7 The security of this method is the strongest for the exchange of public key certificates to start building a web of trust full with introducers Part D Using Public Key Certificate with the Existence of a Direct Introducer D 1 From Public Key File to Public Key Certificate 1 When a public key file is signed by a trusted person known by two parties wishing to have a remote communication the public key file will become a public key certificate refereed by the trusted person who acts as an introducer 2 Public Key Certificate Public Key File Its Signature File Signed by an Introducer 3 When both the sender and receiver have exchanged their respective public key certificate via email mutually verify the introducer s digital signature of the public key file 4 The secure computer communications between the sender and receiver via an insecure channel can now
6. the text in F1 and paste it into a Microsoft Word document called F2 5 After that Alice encrypts the F2 using the security function at the MS Word tool bar Tools gt Options gt Security by using a symmetric key password K1 6 Then Alice sends F1 and encrypted F2 to me the software author using email 7 Alice sends the key password K1 to me using her mobile phone to my mobile phone number 6013 6134998 Malaysia 8 Steps 4 7 can be replaced by steps 9 11 9 After that Alice encrypts the F1 using the encryption function of MobileECC with my attached public key file xpreeli_public_key pub This public key file xpreeli_public_key pub is safer to be downloaded from my website at http www geocities com xpree mobileECC htm 10 Then Alice sends encrypted public key file called F2 to me using email 11 The email communications used in steps 6 10 can be replaced by the storage media of floppy disk CD DVD USB flash drive etc and communicated using postal mail 12 Bob decrypts file F2 using key K1 to get a message to be compared with file F1 12 13 If the decrypted F2 is different from the F1 Bob rejects Alice s public key file 14 If the decrypted F2 is the same as the F1 Bob accepts Alice s public key file 15 Bob can do the same like Alice to send his public key file to Alice 16 The security of this method is subject to my trust level website attack interception attacks of email
7. 28 bit 2D secret is created using 2D key to act as the token password in the 2 factor multimedia key method Secondly an at least 192 bit multimedia data file can be used as software token to be encrypted and stored in a USB flash drive as token ciphertext The token password i e 2D key secret and token plaintext after the optional processes of multihash key can generate a secret to act as a 192 bit private key secret in the 192 bit Mobile ECC Whenever there is a need get the USB flash drive storing the token ciphertext decrypt it using the token password i e 2D key secret and select the hash iteration of multihash key to create a slave key Coming back to the Mobile ECC click the button of Paste Pte to paste the private key The 512 bit hash will be automatically truncated from the beginning to get a 192 bit private key Press the button of Create Public Key Enter the file name of the public key file Select either the file extension of txt or pub Click the button of Save and a public key file will be generated The file directory and file name of the public key file is printed beside the label of Destination File Optionally please fill in the details of the public key holder into the public key file to enable future feature of public key certificate Public key certificate is a signed file having public key and identity identities The signature s can be generated by any trust entities such as cert
8. PKC G 1 Application for Key Sharing Scheme between Two Parties 1 The symmetric key in Part F can be increased to get a list of OTP shared by two parties 2 The OTP can be any string of random ASCII characters 13 3 The OTP list is exchanged between the Alice and Bob using the MePKC MoPKC 4 For each computer communication of electronic file a symmetric key in the OTP list is used and stricken through marked or removed 5 In the next computer communication of electronic file a new symmetric key which is the next in the OTP is used 6 The electronic file in this section can be the file attachment of email 7 The security of this method is subject to the obscurity of OTP list security of MePKC MoPKC and symmetric key encryption 8 The number of OTP lists will be too big when it involves too many bipartite communications Hence this method is encouraged to be used among important users G 2 Application for Instant Messaging Scheme using Instant Messenger between Two Parties 1 The symmetric key in Part F can be increased to get a list of pairs ID OTP shared by two parties 2 The ID can be ordered numbers or any string of random ASCII characters 3 The OTP can be any string of random ASCII characters 4 The ID OTP pair list is exchanged between the Alice and Bob using the MePKC MoPKC 5 The instant messengers are like Yahoo Messenger MSN Windows Messenger Skype AOL Messenger Google Talk Mi
9. Then enter the private key into textbox of Private Key Field 192 bit as in step 4 Click the button of Decrypt The file name of the plaintext file is printed beside the label of Destination File The plaintext file is in the working file directory of Mobile ECC Lastly click the button of Clear Pte to clear the input private key in the clipboard of the computer memory 8 For signature generation check whether the message file has already been included If there is a file directory together with a file name beside the label of Source File message file is included If not click the button of Source File to include the message file Then enter the private key into textbox of Private Key Field 192 bit as in step 4 Click the button of Sign Enter the file name of the signature file Select either the file extension of txt or sig Click the button of Save and a signature file will be generated The file directory and file name of the signature file is printed beside the label of Destination File Optionally please fill in the file name of the signed file into the signature file Do not change anything in the first 6 lines For line 7 and above fields can be added or deleted Lastly click the button of Clear Pte to clear the input private key in the clipboard of the computer memory 9 For signature verification check whether the public key file has already be
10. User Manual for Mobile ECC 2 0 Version 2 0 as at 21Sep08 Requirement Pentium II 266MHz or better 192MB RAM or better Windows XP and Microsoft NET Framework Version 1 1 Redistributable Package 23698KB or better from http www microsoft com Part A Procedure 1 Double click the icon of Mobile_ECC exe Then Figure 1 will be shown UE Mobile Elliptic Curve Cryptosystem 2 0 EIR Private Key Field 192 bit IV Hide Public Key Field a N Paste Pte Clear Pub Include Pub Public Key File Source File Destination File Signature File Create Public Key Encrypt Decrypt Source File Message Sign Verify Signature Fig 1 Starting screen of Mobile ECC mobile elliptic curve cryptosystem 2 This software application provides five functions Public key generation hybrid encryption hybrid decryption signature generation and signature verification 3 Mobile ECC has a hybrid encryption system It uses elliptic curve cryptosystem ECC for two key encryption and Rijndael cipher AES for one key encryption ECC of Mobile ECC implements the elliptic curve of P 192 proposed by CSRC Computer Security Resource Center URL http csrc nist gov NIST National Institute of Standards and Technology URL http www nist gov USA Curve P 192 is in the document of FIPS PUB Federal Information Processing Standards Publications FIPS 186 2 with Change Notice 1 dated October 5 2001 announced on 15 F
11. annel using one key encryption or symmetric key encryption Alice has public key puba and private key pte Bob has public key pubs and private key ptes Alice jots down a secret key with timestamp into a text file encrypts it with pubg and sends the ciphertext to Bob via a communication channel using two key encryption or asymmetric key encryption Then Bob decrypts the Alice s ciphertext using ptep gets the secret key with timestamp encrypts it using puba and sends the ciphertext to Alice Lastly Alice decrypts the Bob s ciphertext using pte and verifies the secret key with timestamp If the verification is accepted the key exchange between Alice and Bob is successful and they can start communicating via the established communication channel using one key encryption If it is rejected it fails 6 13 For challenge and response authentication protocol without shared secret let Alice and Bob to be the two parties intending to authenticate between themselves in a secure communication channel using two key encryption It is similar to the key exchange except the secret key is replaced with a random message Alice has public key puba and private key ptea Bob has public key pubs and private key ptes For Alice to authenticate Bob Alice jots down a random message with timestamp into a text file encrypts it with pubg and sends the ciphertext as challenge to Bob Then Bob decrypts the Alice s ciphertext using ptep g
12. be established 5 The security of this method is subject to the trust level of the direct introducer Part E Using Public Key File without the Existence of a Direct Introducer E 0 Assumptions Alice First party acting as a sender Bob Second party acting as a receiver E 1 First Method Uploading the Alice s Public Key File 1 Alice can upload her public key file to her website that is open to the public 2 Bob can do the same like Alice 3 If Bob does not have personal website then he can try Method E 2 steps 1 to 10 4 The security of this method is subject to the website attacks E 2 Second Method Securely Sending Alice s Public Key File to Bob Using Email amp Mobile Phone 1 Alice uses the software of MobileECC Beta version and creates a public key file called F1 by keeping a private key P1 as secret 2 The secret P1 can be copied into a text file or Microsoft Word document and then stored it into a USB flash drive as a token 3 Alice fills in her details into the F1 4 Select all and copy all the text in F1 and paste it into a Microsoft Word document called F2 5 After that Alice encrypts the F2 using the security function at the MS Word tool bar Tools gt Options gt Security by using a symmetric key password K1 6 Then Alice sends F1 and encrypted F2 to Bob using email 7 Alice sends the key password K1 to Bob using her mobile phone to Bob s mobile phone 8 Bob de
13. crypts file F2 using key K1 to get a message to be compared with file F1 9 If the decrypted F2 is different from the F1 Bob rejects Alice s public key file 10 If the decrypted F2 is the same as the F1 Bob accepts Alice s public key file 11 Bob can do the same like Alice to send his public key file to Alice 12 The security of this method is subject to the interception attacks of email and mobile phone by hackers and network administrators E 3 Third Method Securely Sending Alice s Public Key File to Bob Using Email Floppy Disk CD DVD USB Flash Drive amp Postal Mail 1 Alice uses the software of MobileECC Beta version and creates a public key file called F1 by keeping a private key P1 as secret 2 The secret P1 can be copied into a text file or Microsoft Word document and then stored it into a USB flash drive as a token 3 Alice fills in her details into the F1 4 Select all and copy all the text in F1 and paste it into a Microsoft Word document called F2 10 5 After that Alice encrypts the F2 using the security function at the MS Word tool bar Tools gt Options gt Security by using a symmetric key password K1 6 Then Alice sends F1 and encrypted F2 to Bob using email 7 Alice copies the key password K1 into storage medium like floppy disk CD DVD USB flash drive etc and sends the storage medium with key password K1 to Bob using postal mail 8 Bob decrypts file F2 using key
14. ebruary 2000 URL http csrc nist gov publications fips fips 1 86 2 fips 186 2 changel pdf Any update can be referred at URL http csrc nist gov cryptval dss htm Rijndael cipher of Mobile ECC implements the 192 bit AES Advanced Encryption Standard proposed by CSRC NIST USA It is in the document of FIPS PUB 197 URL http csrc nist gov publications fips fips 197 fips 197 pdf announced on 26 November 2001 The ECC of P 192 has security strength of 96 bits 192 bit AES has security strength of 192 bits Hence the hybrid cryptosystem of Mobile ECC has security strength of 96 bits This is sufficient for the recommended minimum security strength of 80 bits NIST proposed security level of 80 bit key to be phased out by year 2015 and used until year 2010 URL http en wikipedia org wiki Key_size It is published in Table 4 page 66 of the document of NIST SP Special Publication 800 57 Recommendation for Key Management Part 1 General Revised announced in May 2006 URL http csrc nist gov publications nistpubs 800 57 SP800 57 Part1 pdf ECRYPT European Network of Excellence for Cryptology within the European Commission s FP6 Sixth Framework Programme EU URL http www ecrypt eu org listed the protection period for various security levels according to the security strength in bits in Table 7 4 page 29 of ECRYPT Yearly Report on Algorithms and Key Lengths 2005 URL http www ecrypt eu org documents D SPA 16 1 0 pdf
15. en included If there is a file directory together with a file name beside the label of Public Key File public key file is included If not click the button of Include Pub to include the public key file Second check whether the message file has already been included If there is a file directory together with a file name beside the label of Source File message file is included If not click the button of Source File to include the message file Third check whether the signature file has already been included If there is a file directory together with a file name beside the label of Signature File signature file is included If not click the button of Signature to include the signature file To verify the message file and signature file using the public key file click the button of Verify If the textbox of Message displays Valid the message file and signature file are verified Or else if the textbox of Message displays Invalid the message file and signature file shall be rejected 10 Files with the extensions of pub mec and sig can be viewed using WordPad 11 There are two indirect functions for this software application derived from its direct functions Key exchange and challenge and response authentication protocol without shared secret 12 For key exchange let Alice and Bob to be the two parties intending to set up a secure communication ch
16. ets the random message with timestamp encrypts it using puba and sends the ciphertext as response to Alice Lastly Alice decrypts the Bob s ciphertext using pte and verifies the random message with timestamp If the verification is accepted the identity of Bob is authenticated Or else if the verification is rejected the identity of Bob is refused For Bob to authenticate Alice Bob does the similar tasks Bob jots down a random message with timestamp into a text file encrypts it with puba and sends the ciphertext as challenge to Alice Then Alice decrypts the Bob s ciphertext using ptea gets the random message with timestamp encrypts it using pubg and sends the ciphertext as response to Bob Lastly Bob decrypts the Alice s ciphertext using pteg and verifies the random message with timestamp If the verification is accepted the identity of Alice is authenticated Or else if the verification is rejected the identity of Alice is refused At the end Alice and Bob have mutually authenticated one another Part B Urgency amp Importance of Matters B 1 Strongest Communication Modes Between Two or More Humans 1 After checking if there is no active mobile phone and there is no surveillance like sound recorder video camera camcorder etc by using the electronic detector s then the face to face communication between two or more humans is the strongest communication mode 2 To totally avoid surveillance especially sound bui
17. ification authority CA or any introducer s in the communication network Do not change anything in the first 6 lines For line 7 and above fields can be added or deleted Lastly click the button of Clear Pte to clear the input private key in the clipboard of the computer memory 6 For hybrid encryption check whether the public key file has already been included If there is a file directory together with a file name beside the label of Public Key File public key file is included If not click the button of Include Pub to include the public key file Then check whether the source file for hybrid encryption has already been included If there is a file directory together with a file name beside the label of Source File source file is included If not click the button of Source File to include the source file Click the button of Encrypt Enter the file name of the ciphertext file Select either the file extension of txt or mec Click the button of Save and a ciphertext file will be generated The file directory and file name of the ciphertext file is printed beside the label of Destination File 7 For hybrid decryption check whether the ciphertext file has already been included If there is a file directory together with a file name beside the label of Source File ciphertext file is included If not click the button of Source File to include the ciphertext file
18. ld a closed computer communications network in a meeting room where each participant can use a computer linked inside the meeting room only and cut off from the external computer network like LAN and Internet 3 The smallest set up of item 2 is two computers linked using a direct cable in a closed room that can be used by two humans for bi computer communications B 2 Recommended Computer Communications Network 1 Matters Urgent Important Small Message Face to Face Phone using semantic cryptography Email using MePKC 2 Matters Urgent Important Big Message Face to Face Email using MePKC followed by a Phone Reminder 3 Matters Urgent Not Important Small Message Instant Messenger Email Face to Face Phone Mobile Fixed Line 4 Matters Urgent Not Important Big Message Face to Face Email 5 Matters Not Urgent Important Small Message Face to Face Email using MePKC followed by a Phone Reminder 6 Matters Not Urgent Important Big Message Face to Face Email using MePKC followed by a Phone Reminder 7 Matters Not Urgent Not Important Small Message Instant Messenger Email 8 Matters Not Urgent Not Important Big Message Email Part C Using Public Key Certificate amp Meeting Face to Face C 0 Assumptions Alice First party acting as a sender Bob Second party acting as a receiver C 1 From Public Key File to Public Key Certificate 1 Alice and Bob meet
19. ltilingual key input method and system and or 2 factor multimedia key input method and system If 2 dimensional key input method and system is used enter the private key into the textbox of Secret Key Field until the effective key size in the textbox of Key Entropy bit is at least 192 bits Click the button of Hash Key to hash the private key using SHA 512 Then click the button of Copy Hash to copy the 512 bit hash For the multilingual key input method and system please read the user manual for various key styles Once the private key is input to be at least 192 bits all the following steps will be the same as 2 dimensional key input method and system Yet if 2 factor multimedia key input method and system are used select a software token from a multimedia data type such as text image sound or video Create an at least 128 bit password the secret key using conventional method 2D key method or multilingual key Use this password to encrypt the token to become a token ciphertext and store in a USB flash drive for future usage Whenever the software token is needed decrypt the token cuphertext using the password and then click the button of Hash Key to generate a private key for Mobile ECC For private key optimization of 192 bit Mobile ECC software when this software is used together with 2D key input method there is a memory optimization to minimize the memorizable size of private key Firstly a 1
20. ntroducer_1 s mobile phone 10 Introducer_1 decrypts file F2 using key K1 to get a message to be compared with file F1 11 If the decrypted F2 is different from the F1 Introducer_1 rejects Alice s public key file 12 If the decrypted F2 is the same as the F1 Introducer_1 accepts Alice s public key file 11 13 Introducer_1 signs Alice s public key file to generate a digital signature S1 14 Introducer_1 sends the generated digital signature S1 to Alice which when combined with Alice s public key file they become a public key certificate 15 Introducer_1 can do the same like Alice to connect to Introducer_2 16 Steps 6 14 are repeated from Introducer_1 to Introducer_N so as to finally link to Bob 17 In opposite direction Bob can do the same like Alice to send his public key file to Alice 18 The security of this method is subject to the trust level of the introducers interception attacks of email and mobile phone by hackers and network administrators E 5 Fifth Method Securely Sending Alice s Public Key File to Me the Software Author who Acts as an Introducers 1 Alice uses the software of MobileECC Beta version and creates a public key file called F1 by keeping a private key P1 as secret 2 The secret P1 can be copied into a text file or Microsoft Word document and then stored it into a USB flash drive as a token 3 Alice fills in her details into the F1 4 Select all and copy all
21. randa etc 6 For each computer communication of instant messaging using the instant messenger between Alice and Bob an ID is sent from Alice to Bob 7 If the ID has been used before Bob asks Alice to send another ID for a maximum of three ID 8 When Bob gets an ID that has not been used before he looks up the ID OTP pair list to get the corresponding OTP and sends the OTP to Alice using the instant messenger 9 Then Bob strikes through or removes the corresponding ID OTP pair 10 When Alice receives the OTP from Bob if the ID OTP pair is not matched then she asks Bob to send the OTP again for a maximum of three OTP 11 When Alice has matched the OTP received from Bob she strikes through marked or removed the corresponding ID OTP pair 12 Now Alice and Bob can start to send instant messages 13 The security of this method is subject to the man in the middle attack obscurity of ID OTP list security of MePKC MoPKC and symmetric key encryption 14 14 Due to the threat of man in the middle attack the instant messaging using ID OTP list communicated with MePKC MoPKC is not encouraged for important matters It is only suggested for the applications of casual chatting discussion and meeting 15 For urgent matters please use the telephone be it mobile or fixed line 16 The number of ID OTP lists will be too big when it involves too many bipartite communications Hence this method i
22. s encouraged to be used among important users i The End 15
23. y space password space n Number of computers L Maximum lifetime of a password R Number of guesses per unit of time per unit of computer P Probability that a password can be guessed in its lifetime Let S Number of keys in bits n 10 29 9 bits L 5 10 20 30 50 100 300 years 27 2 28 2 29 2 29 8 30 6 31 6 33 1 bits R 1 5 x 10 23 8 bits best PC performance by the end of year 2005 R 1 second per slow computer using key stretching P 10 19 9 bits Considering variety of computers and Moore s Law Computer performance varies from to 10 times 0 05second per fast computer to 1 second per slow computer gt log gt 20 4 3 bits Moore s Law ML The number of transistors per chip doubles every 2 years gt L in year 2 bits S n L R P 24 2 Table 1 Taking R 1 5 x 10 23 8 bits without key strengthening L year n bit L bit R bit P bit 0 05 Is ML bit S bit ECC 2S 5 29 9 27 2 23 8 19 9 0 2 5 103 3 206 6 10 29 9 28 2 23 8 19 9 0 5 106 8 213 6 20 29 9 29 2 23 8 19 9 0 10 112 8 225 6 30 29 9 29 8 23 8 19 9 0 15 118 4 236 8 50 29 9 30 6 23 8 19 9 0 25 129 2 258 4 100 29 9 31 6 23 8 19 9 0 50 155 2 310 4 300 29 9 33 1 23 8 19 9 0 150 256 7 513 4 The number of loops in the key stretching or key strengthening has to be increased by 1 bit for every 2 years Then the security of a cryptosystem can
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