Storage apparatus access control apparatus for a recording medium
Contents
1. 40 45 50 55 60 65 2 the user password can be read out from the recording medium Moreover there is another method of physically obtaining the password with the use of a test and repair tool Thus a malicious service person can obtain the user pass word using the service command and access to the recording medium with the use of this user password In short it is actually possible to steal alter and delete data on the recording medium in the service center and hence it would be a serious security hole Such security problems may be solved by following the procedure shown in FIG 6 Specifically when a recording medium including a storage apparatus has some defect the user U or the user U brings the defective recording medium to the service center SV or the service center SV In this case in order to avoid the security hole the authority in the service center SV or SV only listens to the problems with the recording medium but does not actually provide a service to the defect The recording medium is then sealed for confidential reasons in the service center SV or SV and sent to an expert H The expert H is a person who is exclusively appointed for providing a service to defects and it is sup posed that he does not do anything with the data inside The expert H analyzes the defect in the recording medium and then informs the user U or the user U of the result of analysis and returns the recording2. 121 B1 11 ENIGMA IDEA and a hashing function Namely any coding algorithm can be used if it is a one way function As explained above according to this invention since a coded password produced from a user password using a one way function is written on a recording medium a third party including a service person can not derive the user password from the coded password because of the charac teristics of the one way function Since the third party can not actually obtain the user password by using whatever means it is possible to prevent unauthorized access to the recording medium thereby producing the effect of signifi cantly improving the security Moreover since a highly secured recording medium can be given to the user it is possible to produce the effect of improving the customer service Furthermore since a ser vice person general operator or part time operator hired at lower salary than an expert can provide a service to the defect in the recording medium while assuring the security it is possible to lower the costs of service and maintenance In addition when setting or changing a user password whether a user performing the setting is an authorized person or not is checked by password checking and a new coded password is written on the recording medium only when the two passwords match Thus this invention pro duces the effect of assuring the security even after the setting Although the invention has bee
3. XW to the checking section 16 In the next step SA3 the coding section 15 produces the coded password XW from the user password PW using the coding algorithm see FIG 2A to FIG 2C and then passes the coded password XW to the checking section 16 Accordingly in step SA4 the checking section 16 com pares the coded password XW and the coded password XW In other words the checking section 16 judges whether the coded password XW matches the coded pass word XW Assuming that the user password PW is prop erly input by an authorized user having a right to access to the recording medium 40 the coded password XW will match the coded password XW In this case therefore the checking section 16 considers the result of judgement as Yes and proceeds to step SAS In step SAS after outputting the access permitting signal S to the access control section 19 the checking section 16 10 15 20 35 40 45 50 55 60 65 8 completes sequence of processing When the access per mission signal S is input the access control section 19 gives the command executing section 18 a permission to access the recording medium 40 The command executing section 18 controls the optical head 24 to access the recording medium 40 according to the command for example a read command and read out the data D from the recording medium 40 The data D is output to the computer 30 through the SCSI cable by the interface control
4. and q Further since the one way function is used in order to code the passwords the third party including a service person for maintaining the recording medium etc can not derive the user password from the coded password because of the characteristics of the one way function Thus accord ing to the invention of the above aspect since in reality the third party can not obtain the user password by using whatever means it is possible to prevent unauthorized access to the recording medium thereby achieving a sig nificant improvement in the security Moreover since a highly secure recording medium can be provided for the users the customer service can be improved Furthermore according to the invention of the above aspect since a service person general operator or part time operator hired at a lower salary than an expert may provide a service to the defect in the recording medium while assuring the security it is possible to lower the costs of service and maintenance Further when setting a user password the coding unit produces the old coded password and the new coded pass word by coding the old user password and the new user password respectively with the one way function Then the checking unit compares the old coded password and the coded password read out from the recording medium and the setting unit writes the new coded password on the recording medium only when the checking unit judges that these coded passwords m
5. section 12 Then the computer 30 reproduces the data D Thus when the user inputs a correct password PW since the result of judgement in step SA4 is Yes access to the recording medium 40 is permitted Following description will explain an operation per formed when an unauthorized third party pretends to be an authorized user and tries to read out the data D unjustly from the recording medium 40 In this case in step SA1 shown in FIG 3 after setting the recording medium 40 in the tray 28 the third party inputs a command for example a read command and the user password PW through the input device 31 However since the third party does not know a password the password PW input here is a wrong password The command and the wrong user password PW are sent to the storage apparatus 10 through the SCSI cable by the com puter 30 After the command and the wrong user password PW are received by the interface control section 12 they are stored in the buffer memory 20 The command analyzing section 13 then analyzes the command and passes the result of analysis to the command executing section 18 and also passes the wrong user password PW to the coding section 15 Accordingly in step SA2 the command executing section 18 reads out the coded password XW from the recording medium 40 and then passes the coded password XW to the checking section 16 In the next step SA3 the coding section 15 produces the coded password XW from
6. the wrong user password PW using the coding algorithm and then passes the coded password XW to the checking section 16 The coded password XW produced here is also a wrong coded pass word Accordingly in step SA4 the checking section 16 com pares the coded password XW and the wrong coded password XW In this case since the coded password XW and the wrong coded password XW do not match the checking section 16 considers the result of judgement as No and proceeds to step 5 6 In step SA6 after outputting the access prohibition signal S to the access control section 19 the checking section 16 completes a sequence of pro cessing When the access prohibition signal 5 is input the access control section 19 prohibits the command executing section 18 from accessing to the recording medium 40 Accordingly the command executing section 18 does not execute the command in this case a read command therefore the third party can not obtain the data D from the recording medium 40 The third party may try to obtain the correct user pass word PW with the use of the above mentioned maintenance use test and repair tool However the password read out from the recording medium 40 with the use of the test and repair tool will be the coded password XW As described above the coded password XW is a password produced by coding the user password PW with a one way function coding algorithm Therefore the third party can no
7. when the passwords compared by said checking unit match and prevents access to said recording medium when the passwords do not match 5 An access control method for a recording medium comprising the steps of generating a coded password from a user password input by a user using a one way function reading a coded password from a recording medium comparing the coded password generated at the coding step and the coded password read out from said record ing medium and permitting access to said recording medium if the two coded passwords match and prevents access to said recording medium when the two coded passwords do not match 6 The access control method according to claim 5 further comprises a setting step of setting the password wherein at the password generating step an already set user password and a new user password to be newly set which are input by the user are encoded using the one way function to generate an old coded password and a new coded password respectively in the password comparing step the old coded password generated at the password generating step and the coded password read out from said recording medium are compared and in the setting step the new coded password is written on said recording medium when it is judged at the pass word comparing step that the old coded password and the coded password read out from said recording medium match with each other 7 An access control method for a recor
8. 12 controls communications between the storage apparatus 10 and the computer 30 The interface control section 12 receives commands data passwords etc from the computer 30 and temporarily stores them in a buffer memory 20 The buffer memory 20 is a DRAM dynamic random access memory and temporarily stores the data to be written on the recording medium 40 and the data D read out from the recording medium 40 as well as commands and the user password PW Besides the interface control section 12 sends the readout data D to the computer 30 A command analyzing section 13 analyzes a command stored in the buffer memory 20 and identifies the type of the command Examples of such a command are a command for reading out the data D from the recording medium 40 a command for writing data on the recording medium 40 and a command for setting a user password A coding checking section 14 performs a function of coding the user password PW or the user password PW input by a user using the coding algorithm and a function of checking the password before reading out the data D from the recording medium 40 The coding checking section 14 includes a coding section 15 a checking section 16 and a coding section 17 The coding section 15 produces a coded password from the user password PW with the help of the coding algorithm The checking section 16 compares the coded password XW and the coded password XW read out from the recording med
9. 2112 7 995 JP 7182244 7 995 JP 8255232 10 1996 JP 11053264 2 1999 JP 11213551 8 1999 WO 9628820 9 1996 OTHER PUBLICATIONS Tadahiro Uezono et al Cipher and Data Security Baihu kan 1988 pp 164 167 cited by examiner Primary Examiner Thomas R Peeso 74 Attorney Agent or Firm Greer Burns amp Crain Ltd 57 ABSTRACT A storage apparatus includes a recording medium 40 on which a coded password XW generated by coding a password assigned to a user using a coding algorithm one way function is recorded A coding section produces a coded password XW by coding a password PW input by the user using the coding algorithm and a checking section compares the coded passwords XW and XW An access control section permits access to the recording medium when the checking section judges that the passwords XW and XW match while barring access when the passwords XW and XW do not match 8 Claims 6 Drawing Sheets 19 i ACCESS VOLTAGE7 i CONTROL TEMPERATURE SECTION CONTROL SECTION 40 D DATA XW1 GODED PASSWORD U S Patent Aug 17 2004 Sheet 1 of 6 US 6 779 121 B1 FIG 1 DISPLAY APPARATUS 31 30 INPUT COMPUTER APPARATUS 19 STORAGE APPARATUS pu e a INTERFACE CONTROL SECTION i COMMAND Bus ANALYZING SECTION ae wae 115 i CODING CODING yw i SECTION SECTION SUSA a4 gs CHECKING ACCESS VOLTAGE o SECTION CONTROL TEM
10. 40 A movable tray 28 is provided for storing the recording medium 40 during writing reading The eject motor 27 drives the tray 28 when ejecting the recording medium 40 The spindle motor 26 drives and rotates the recording medium 40 stored in the tray 28 during writing reading Referring now to the flowcharts shown in FIG 3 and FIG 4 the following description will explain the operation of this embodiment To begin with password checking according to this embodiment will be explained with reference to FIG 3 It is assumed that the data D and the coded password XW are recorded on the recording medium 40 shown in FIG 1 In step SA1 shown in FIG 3 after setting the recording medium 40 in the tray 28 a user inputs a command for example a read command and the user password PW through the input device 31 As a result the command and the user password PW are sent to the storage apparatus 10 through the SCSI cable by the computer 30 When the command and the user password PW are received by the interface control section 12 they are stored in the buffer memory 20 The command analyzing section 13 then analyzes the command and passes the result of analysis to the command executing section 18 and also passes the user password PW to the coding section 15 Accordingly in step SA2 the command executing section 18 controls the optical head 24 to read out the coded password XW from the recording medium 40 and then passes the coded password
11. IUM TO SERVICE CENTER SERVICE CENTER ANALYZE THE DEFECT IN THE RECORDING MEDIUM ACCORDING TO SERVICE MANUAL USER DEFECT OCCURS BRING RECORDING MEDIUM TO SERVICE CENTER SERVICE CENTER ANALYZE THE DEFECT IN THE RECORDING MEDIUM ACCORDING TO SERVICE MANUAL SV1 DECIDE THE CAUSE DECIDE THE CAUSE SEND RECORDING SEND RECORDING MEDIUM MEDIUM EXPERT ANALYZE THE DEFECT IN THE RECORDING MEDIUM U S Patent Aug 17 2004 Sheet 6 of 6 US 6 779 121 B1 FIG 6 RETURN THE RETURN THE RECORDING RECORDING Ut MEDIUM REPLAY U2 MEDIUM REPLAY TO THE USER TO THE USER USER DEFECT OCCURS BRING RECORDING MEDIUM TO SERVICE CENTER SERVICE CENTER USER DEFECT OCCURS BRING RECORDING MEDIUM TO SERVICE CENTER SERVICE CENTER SV1 SEAL THE RECORDING MEDIUM FOR SECURITY REASONS SEAL THE RECORDING MEDIUM FOR SECURITY REASONS SEND RECORDING MEDIU SEND RECORDING MEDIUM M i EXPERT ANALYZE THE DEFECT IN THE RECORDING MEDIUM US 6 779 121 B1 1 STORAGE APPARATUS ACCESS CONTROL APPARATUS FOR A RECORDING MEDIUM AND ACCESS CONTROL METHOD FOR A RECORDING MEDIUM FIELD OF THE INVENTION The present invention relates to a storage apparatus an access control apparatus for a recording medium and an access control method for a recording medium having a function of preventi
12. PERATURE TEC SECTION CONTROL SECTION 9 20 i EXECUTING oy SECTION 22 21 f SIGNAL DRIVE PROCESSING CONTROL SECTION SECTION 23 AMPLIFYING 25 SECTION i ACTUATOR 24 l OPTICAL zo l HEAD SPINDLE MOTOR La 27 28 EJECT MOTOR TRAY 40 D DATA XW1 CODED PASSWORD E U S Patent Aug 17 2004 Sheet 2 of 6 US 6 779 121 B1 FIG 2A key FIG 2B XP pP Y mod q XWy XP 1 FIG 2C key 0x1234567801234567 U S Patent Aug 17 2004 Sheet 3 of 6 US 6 779 121 B1 FIG 3 INPUT A COMMAND AND USER PASSWORD PW SA1 READ OUT CODED PASSWORD XW FROM RECORDING MEDIUM 40 SA2 GENERATE CODED SA3 PASSWORD XW OUTPUT ACCESS PROHIBITION SIGNAL So OUTPUT ACCESS PERMISSION SIGNAL S U S Patent Aug 17 2004 Sheet 4 of 6 US 6 779 121 B1 FIG 4 INPUT A COMMAND USER SB1 PASSWORD PW AND NEW USER PASSWORD PW READ OUT CODED SB2 PASSWORD XW FROM RECORDING MEDIUM 40 GENERATE CODED SB3 PASSWORD XW SB4 No GENERATE CODED PASSWORD CONSIDER THE RESULT OF SETTING AS ERROR OUTPUT ENABLE SIGNAL Se END U S Patent Aug 17 2004 Sheet 5 of 6 US 6 779 121 B1 FIG 5 RETURN THE RETURN THE U1 RECORDING u2 RECORDING MEDIUM REPLAY MEDIUM REPLAY TO THE USER TO THE USER USER DEFECT OCCURS BRING RECORDING MED
13. a United States Patent Uchida et al US006779121B1 10 Patent No 45 Date of Patent US 6 779 121 B1 Aug 17 2004 54 STORAGE APPARATUS ACCESS CONTROL APPARATUS FOR A RECORDING MEDIUM AND ACCESS CONTROL METHOD FOR A RECORDING MEDIUM 75 Inventors Yoshiaki Uchida Kanagawa JP Hiroyuki Kobayashi Kanagawa JP 73 Assignee Fujitsu Limited Kawasaki JP Notice Subject to any disclaimer the term of this patent is extended or adjusted under 35 U S C 154 b by 0 days 21 Appl No 09 496 740 22 Filed Feb 3 2000 30 Foreign Application Priority Data 701 9 1999 ieu teens 11 196770 51 Intz E REN G06F 1 24 52 U S Cl 713 202 713 182 713 183 713 184 713 200 713 201 58 Field of Search 713 202 182 713 183 184 200 201 56 References Cited U S PATENT DOCUMENTS 5 198 806 3 1993 Lord 713 200 5 497 421 A 3 1996 Kaufman et al 713 156 5 644 444 A 7 1997 Braithwaite et al 360 60 5 821 871 10 1998 340 5 8 32 CONTROL SECTION 4 COMMAND ANALYZING SECTION En M PW3 k zi CHECKING 4 SECTION i COMMAND EXECUTING SECTION SIGNAL PROCESSING SECTION FOREIGN PATENT DOCUMENTS JP 57150117 9 1982 JP 60189531 9 1985 JP 63175955 7 1988 JP 1309120 12 1989 JP 718
14. atch Thus when setting or changing a user password whether or not a user performing the setting is an authorized person is checked by password checking and a new coded pass word is written on the recording medium only when the passwords match Thus the security is assured even after the setting According to another aspect of this invention when a user password is input the coding unit produces a coded pass word from the user password input by the user with the use of the one way function Next the checking unit compares the produced coded password and a coded password read out from the recording medium Then the access control unit permits access to the recording medium only when the passwords compared by the checking unit match Thus when a wrong password is input by an unauthorized third party the checking unit judges that the passwords do not match and access to the recording medium is prohibited Since the coded password produced from the user pass word with the use of the one way function is written on the recording medium the third party including a service person can not derive the user password from the coded password because of the characteristics of the one way function Thus according to the invention of the third aspect since in reality the third party can not obtain the user password by using whatever means it is possible to prevent 10 15 20 25 30 35 40 45 50 55 60 65 4 un
15. authorized access to the recording medium thereby achieving a significant improvement in the security Moreover while a highly secure recording medium can be provided to the users the customer service can be improved Furthermore according to the invention of the third aspect since a service person hired at a lower salary than an expert may provide a service to the defect in the recording medium while assuring the security it is possible to lower the costs of service and maintenance According to another aspect of this invention when the user inputs a password this password is coded using a one way function in a coding step A password coded in the same manner is already stored in the recording medium and this password is read in a reading step In a checking step the password coded input by the user and the password read out from the recording medium are compared An access control unit permits the access to the recording medium if the two passwords match and prohibits the access when they do not The password input by an unauthorized person will not match with the password recorded on the recording Therefore access to the recording medium by the unautho rized person can be prohibited Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is a block diagram showing the structure of an embodiment acco
16. ce person general operator or part time operator hired at a lower salary than the expert H Hence according to this embodiment since the amount of the recording media sent to the expert H can be decreased compared with the prior art it is possible to reduce the number of the experts H thereby lowering the costs of service and maintenance In the above an embodiment of the present invention has been described in detail with reference to the drawings However the specific structure of the present invention is not necessarily limited to this embodiment and modifica tions of the design within the scope of the invention are also included in the present invention For instance in this embodiment a magneto optical disk is explained as an example of the recording medium 40 However the types of the recording media are not restricted if the recording media need to be secured to protect the recorded data from unau thorized access Accordingly the present invention is applicable not only to other recording media such as floppy disks magnetic disks optical disks phase transition type optical disks IC integrated circuit cards memory cards and magnetic strip cards but also to an apparatus incorporating a recording medium such as a magneto optical disk device Moreover in this embodiment although three coding algorithms are explained with reference to FIG 2A to FIG 2C it is possible to use other coding algorithms such as US 6 779
17. coding section 17 The term coding algorithm referred here means an algorithm for producing a coded password XW y 1 2 3 from a user password PW y 1 2 3 with the use of a one way function The one way function has such characteristics that it is easy to obtain a function F x from a variable x but it is difficult to obtain the variable x from the value of the function F x It is thus difficult to obtain the user password PW from the coded password XW produced by the coding algorithm Thus it is actually impossible for a third party who tries to perform unauthorized access to obtain the user password PW from the coded password XW Hence the coded password XW is an extremely effective password for assur ing security In a coding algorithm shown in FIG 2A fixed values for example all zero which are kept secret from general people are input and the coded password XW is produced by using the user password PW as a key with the fixed values by a DES data encryption standard cipher system The DES cipher system is a standard cipher system established by the National Institute of Standards and Technology in 1977 Besides in a coding algorithm shown in FIG 2B a calculation of an exponential remainder is used Specifically in this coding algorithm an exponential remainder XP p mod where p and q are prime numbers and PW is the user password is calculated and then a result obtained by subtracting o
18. d recording area of the recording medium 40 the new coded password XW is overwritten on the coded password XW Thereafter the user can obtain the data D from the recording medium 40 by inputting the new user password PW in the above mentioned password checking process see FIG 3 Incidentally in step SB4 if the result of judgement is No the checking section 16 considers the result of setting as error and does not output signal In this case therefore the password is not changed As explained above according to this embodiment since coded password produced from a user password with the use of a one way function coding algorithm is written on 10 15 20 25 30 35 40 45 50 55 60 65 10 the recording medium the third party including a service person can not derive the user password from the coded password due to the characteristics of the one way function Hence according to this embodiment since in reality the third party can not obtain the user password by using whatever means it is possible to prevent unauthorized access to the recording medium 40 thereby achieving a significant improvement in the security Moreover accord ing to this embodiment since a highly secure recording medium 40 can be given to the user the customer service can be improved Referring now to FIG 5 the following description will explain the procedure to be followed when the recording medium 40 has so
19. ding medium comprising the steps of recording a coded password generated by coding a pass word assigned to a user using a one way function on a recording medium generating a coded password from a user password input by a user using a one way function reading the coded password from said recording medium comparing the coded password generated at the coding step and the coded password read out from said record ing medium and permitting access to said recording medium if the two coded passwords match and prevents access to said recording medium when the two coded passwords do not match 8 An access control method for a recording medium which method controls access to a recording medium on which a coded password produced by coding a user pass US 6 779 121 B1 13 14 word assigned to a user with a one way function is recorded permitting access to said recording medium if the two the method comprising the steps of coded passwords match and prevents access to said generating a coded password by coding the user password recording medium when the two coded passwords do input by the user utilizing the one way function not match comparing the coded password generated at the coding 5 step and the coded password read out from said record ing medium and k A
20. e coded password XW from the recording medium 40 and then passes the coded password XW to the checking section 16 In the next step SB3 the coding section 15 produces the coded password XW from the user password PW using the coding algorithm and then passes the coded password to the checking section 16 Accordingly in step SB4 the checking section 16 com pares the coded password XW and the coded password XW In other words the checking section 16 judges whether the coded password XW matches the coded pass word XW Assuming that the user password PW is prop erly input by an authorized user having a right to access to the recording medium 40 the coded password XW will match the coded password XW In this case therefore the checking section 16 decides the result of judgement as Yes and proceeds to step SBS In the next step SB5 the coding section 17 generates a coded password XW from the new user password PW using the coding algorithm and then passes the coded password XW to the command executing section 18 In the next step SB7 since the result of judgement in step SB4 is Yes the checking section 16 outputs the write enable signal S to the command executing section 18 Accordingly the command executing section 18 controls the optical head 24 to access to the recording medium 40 and write the new coded password XW in the coded password recording area of the recording medium 40 Therefore in the coded passwor
21. ecking unit judges that the old coded password and the coded password read out from said recording medium match with each other 3 A storage apparatus comprising a recording medium on which a coded password gener ated by coding a password assigned to a user using a one way function is recorded coding unit which generates a coded password from a user password input by a user using the one way function a reading unit which reads out a coded password from a recording medium 10 20 25 40 45 50 55 60 12 a checking unit which compares the coded password generated by said coding unit and the coded password read out from said recording medium and an access control unit which permits access to said recording medium if the two coded passwords match and prevents access to said recording medium if the two coded passwords do not match 4 An access control apparatus for a recording medium having a function of controlling access to a recording medium on which a coded password produced by coding a user password assigned to a user with a one way function is recorded comprising coding unit which produces a coded password by coding the user password input by the user utilizing the said one way function a checking unit which compares the coded password produced by said coding unit and the coded password read out from the recording medium and an access control unit which permits access to said recording medium
22. ium 40 before granting access to the recording medium 40 and outputs an access permission signal S to an access control section 19 when the two passwords match The access permission signal S is a signal for permitting an access reading writing to the recording medium 49 On the other hand if the coded password XW and the coded password XW do not match the checking section 16 outputs an access prohibition signal S to the access control section 19 The access prohibition signal S is a signal for prohibiting an access reading writing to the recording medium 40 Like the coding section 15 the coding section 17 pro duces a coded password XW from a new user password PW with the help of a coding algorithm This user password PW is a new user password used when changing the already set user password PW Further the checking section 16 10 15 20 35 40 45 50 55 60 65 6 compares the coded password XW and the coded password XW before changing the user password PW to the user password PW and outputs a write enable signal S to command executing section 18 only when these passwords match This write enable signal S is a signal for instructing writing of the new coded password XW in the coded password recording area of the recording medium 40 Referring now to FIGS 2A to 2C the following descrip tion will explain examples of the coding algorithms used in the above mentioned coding section 15 and
23. ium 40 is an autho rized person In other words the user password PW is used by a user for assuring security and preventing unauthorized writing reading from being performed by a third party User password PW shown in FIG 1 is a new password used US 6 779 121 B1 5 when changing the user password PW The user password PW will be explained in detail later The recording medium 40 is for example a disk shaped MO magneto optical disk which allows optical writing reading of data and is contained in a resin case C Data D is recorded on the recording medium 40 in a data recording area and a coded password XW is recorded in a coded password recording area The data D may be image data contents information such as music various application programs etc Thus the recording medium 40 is given to the user by a provider with or without cost Besides a coded password XW is a password produced by coding a user password by a coding cipher algorithm An input device 31 is a keyboard a mouse etc and used for the entry of the above mentioned password as well as various inputs A display device 32 is a CRT cathode ray tube LCD liquid crystal display etc and displays data to be written on the recording medium 40 and data read out from the recording medium 40 In this storage apparatus 10 a voltage temperature control section 11 controls a power supply voltage and the tempera ture in the device An interface control section
24. later described actuator 25 spindle motor 26 and eject motor 27 and performs servo control A signal processing section 22 modulates data to be written on the recording medium 40 US 6 779 121 B1 7 and demodulates a readout signal from an optical head 24 An amplifying section 23 amplifies the signal read by the optical head 24 This optical head 24 is a read write head that is provided adjacent to a recording surface of the recording medium 40 and has a function of writing data on the recording medium 40 and a function of reading out data from the recording medium 40 by irradiating laser light La on the recording surface of the recording medium 40 The optical head 24 includes a semiconductor laser for generating the laser light La an objective lens for narrowing down the beam diameter of the laser light La to be irradiated on the recording surface of the recording medium 40 optical components collimate lens and beam splitter for guiding the laser light LA generated by the semiconductor laser to the objective lens and a light receiving element for receiving reflected light from the recording medium 40 and converting the reflected light to an electrical signal The actuator 25 includes a drive coil and moves the objective lens of the optical head 24 in a radial direction of the recording medium 40 and a focusing direction Here the focusing direction denotes a direction perpendicular to the recording surface of the recording medium
25. me defect In FIG 5 when the recording medium including the storage apparatus has some defect a user U or a user U brings the defective recording medium to a service center SV service center SV In this case since the security of the recording medium is assured as described above the people in the service center SV on the service center SV will not only listens to the defect in the recording medium but can also provide some basic service for the defect by a service person who may be a general operator or a part time operator More specifically the service person will analyze the defect in the recording medium with the help of a service manual and decide the cause As a result when the cause of the defect is found the service person informs the user U or the user U5 of the result of analysis and returns the recording medium to the user or the user On the other hand when the cause of the defect can not found by the basic service H the recording medium is sent to an expert in a sealed state for confidential reasons from the service center SV or SV The expert H then analyzes the defect in the recording medium as a secondary service and then informs the user U or the user U of the result of analysis and returns the recording medium to the user U user U Thus according to this embodiment since the security is assured in the service centers SV and SV the primary service can be provided by the servi
26. medium to the user U or the user U However according to the procedure shown in FIG 6 in order to achieve a quick reply return to the user user U it is necessary to employ many experts H who are hired at high salary Consequently there is a problem that the costs of service and maintenance are increased Moreover if many experts H are hired it would raise a possibility that the information relating to the above mentioned service command is leaked out to general users In such a case because a certain user might know a user password of a recording medium belonging to another person and unjustly access to the recording medium an authorized user will be anxious Therefore the quality of the customer service will be lowered Meanwhile a magnetic strip card as another example of the recording medium also assures the security by password checking In the case of the magnetic strip card however the password can be obtained by applying magnetic powder or the like to a recorded area without using a special device SUMMARY OF THE INVENTION In view of the above mentioned problems an object of the present invention is to provide a storage apparatus an access control apparatus for a recording medium and an access control method for a recording medium capable of improv ing the security of the recording medium reducing the costs of service and maintenance and improving the customer service According to one aspect of this i
27. n described with respect to a specific embodiment for a complete and clear disclosure the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth What is claimed is 1 A storage apparatus comprising coding unit which generates a coded password from a password input by a user using a one way function a reading unit which reads out a coded password from a recording medium a checking unit which compares the coded password generated by said coding unit and the coded password read out from said recording medium and an access control unit which permits access to said recording medium if the two coded passwords match and prevents access to said recording medium if the two coded passwords do not match 2 The storage apparatus according to claim 1 further comprises a setting unit for setting the password wherein said coding unit encodes an already set user password and a new user password to be newly set which are input by the user using the one way function to generate an old coded password and a new coded password respectively said checking unit compares the old coded password generated by said coding unit and the coded password read out from said recording medium and said setting unit writes the new coded password on said recording medium when said ch
28. ne from the exponential reminder XP is used as the coded password XW The prime numbers p and q are extremely large values between 2190 and 23 Further in a coding algorithm shown in FIG 2C first a value A is calculated by assigning the user password PW in an equation A PW rot 13 Exponential remainder XA is then calculated by assigning the prime numbers p and q and the value A in an equation XA p mod q where p and q are prime numbers Subsequently like in the above mentioned coding algo rithm shown in FIG 2A the exponential remainder XA is used as a key with the values 0x1234567801234567 which are kept secret from general people to produce the coded password XW by the DES data encryption standard cipher system The coding section 15 and coding section 17 shown in FIG 1 perform coding with the use of any one of the above described three coding algorithms The command executing section 18 executes writing reading password setting etc according to the result of analysis of the command analyzing section 13 the write enable signal S etc The operation of the command execut ing section 18 will be explained in detail later The access control section 19 controls access to the recording medium 40 according to the access permission signal S or the access prohibition signal S input from the checking section 16 The access control will be described in detail later drive control section 21 supplies a drive voltage to
29. ng a third party from unjustly accessing to the recording medium using a password More particularly this invention relates to a technology for improving the security by recording a coded password produced by coding a user password with a one way func tion on the recording medium BACKGROUND OF THE INVENTION In recent years storage apparatuses including various types of recording media are being developed In particular with the spread of personal computers the storage appara tuses generally use removable media such as magneto optical disks floppy disks and optical disks as the recording media Although the recording media of this type have the advantage of easy handling because of their small size and light weight they have also the disadvantages that they can easily be taken away by a third party and the data can easily be stolen or altered Therefore passwords or the like have been conventionally used to prevent stealing and alteration of the data In a conventional storage apparatus in order to improve the security by preventing unauthorized access reading writing and deletion by a third party a password is set in advance in a recording medium and an internal memory of the device When a user inputs a password the user may be an authorized person or a third party it is compared with the already recorded password and access to the recording medium is permitted only when the two passwords match The storage apparatus ex
30. nvention when the user inputs a password a coding unit codes this password using a one way function A password coded in the same manner is already stored in the recording medium and a reading unit reads this password A checking unit compares the password coded input by the user and the password read out from the recording medium An access control unit permits the access to the recording medium if the two passwords match and prohibits the access when they do not The password input by an unauthorized person will not match with the password recorded on the recording Therefore access to the recording medium by the unauthorized person can be prohibited US 6 779 121 B1 3 The one way function means a function having such characteristics that a value Y in this case the coded password of the function is relatively easily obtained from an input Y in this case the user password but it is difficult to obtain an input x from the value Y based on the current mathematical knowledge For instance it has been known that it is relatively easy to multiply large prime numbers together but it is difficult to obtain the original two prime numbers by resolving the product into factors Moreover for prime numbers p and q it has been known that it is easy to calculate the power of the prime number p with the prime number q as a devisor but it is extremely difficult to perform the reverse calculation for certain values of the prime numbers p
31. plained above is described in detail in Japanese Patent Application Laid Open Nos SHO 57 150117 SHO 60 189531 SHO 63 175955 and HEI 01 309120 In a storage apparatus of this type the password recorded in the recording medium and internal memory of the device is an unprocessed data namely which has not been subjected to any processing or data which is almost analogous to the unprocessed data Such an access control by password checking is useful when for example a removable recording medium on which images music data application programs or the like are recorded is to be rent to the user In other words in this case by recording a password on a recording medium it is possible to permit only a specified user to access to the recording medium By the way it is mentioned in the above that a password written in the recording medium and the internal memory of the device is unprocessed data or almost analogous to the unprocessed data Even when the password is unprocessed data it is possible to prevent unauthorized access by general users by performing the above described password checking or by recording the password in a recording area which can not be read by any known command However in a service center providing a maintenance service for defects for the storage apparatus and the recording medium when a service person inputs a hidden maintenance command categorized as a service command 10 15 20 25 30 35
32. rding to the present invention FIG 2A to FIG 2C are diagrams showing examples of coding algorithms according to this embodiment FIG 3 is a flowchart explaining a password checking process according to this embodiment FIG 4 is a flowchart explaining a password setting or changing process according to this embodiment FIG 5 is a diagram explaining a procedure to be followed when a recording medium has some defect according to this embodiment and FIG 6 is a diagram explaining problems of a conventional example DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the attached drawings the following descrip tion will explain in detail an embodiment of a storage apparatus an access control apparatus for a recording medium and an access control method for a recording medium according to the present invention FIG 1 is a block diagram showing the structure according to the present invention In FIG 1 a storage apparatus 10 is a device for writing reading data on a removable recording medium 40 according to a command from a computer 30 The computer 30 is connected to the storage apparatus 10 through a not shown SCSI small computer system interface cable The computer 30 sends commands for instructing writing reading data on the recording medium 40 data a user password PW etc to the storage apparatus 10 This user password PW is used for checking whether a person trying to write read data on the recording med
33. t obtain the user password PW because it is impossible to obtain the user password US 6 779 121 B1 9 PW from the readout coded password XW due to the characteristics of the one way function In other words the third party can not read out the data D unjustly from the recording medium 40 by using whatever means Referring now to FIG 4 the following description will explain setting changing of a password according to this embodiment With the following procedure the user pass word PW which has already been set as mentioned in the explanation of FIG 1 can be changed to a new password PW In step SB1 shown in FIG 4 the user sets the recording medium 40 in the tray 28 and then inputs a command for example a set command the already set user password PW and the new password PW using the input device 31 The computer 30 sends the command the user password PW and the user password PW to the storage apparatus 10 through the SCSI cable When the command the user password PW and the user password PW are received by the interface control section 12 they are stored in the buffer memory 20 The command analyzing section 13 then analyzes the command and passes the result of analysis to the command executing section 18 and also passes the user passwords PW and PW to the coding section 15 and coding section 17 respectively Accordingly in step SB2 the command executing section 18 controls the optical head 24 to read out th
Download Pdf Manuals
Related Search