Apparatus and method for generating data for detecting false alteration of encrypted data during processing

• US 20040172543A1
• Filed: 01/14/2004
• Published: 09/02/2004
• Est. Priority Date: 07/17/2001
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Sawada, Yuji, Sato, Katsuhiko
• Granted Patent: US 7,751,556 B2
• Time in Patent Office: Days
• US Class Current: 713/187
• CPC Class Codes: G06F 21/64 Protecting data integrity, e.g. using checksums, certificates or signatures
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/3239 involving non-keyed hash functions, e.g. modification detection codes [MDCs], MD5, SHA or RIPEMD

Abstract

Data to be encrypted (301) is partially extracted successively. A result of encrypting a previously extracted portion of the data is used to successively calculate that of encrypting the currently extracted portion of the data successively. Successively calculated results of the encryption are used to generate encrypted data (305). In generating the encrypted data, a finally calculated result of the encryption (PF (z+1)) is attached to the generated encrypted data. The finally calculated result is used as falsification detecting data (308) for detecting whether the data to be encrypted is falsified data.

Claims

1. A method of encryption comprising the steps of:

encrypting data to be encrypted (301, Bk) to generate encrypted data (305, CBk) (S102, S602); and

attaching data (PF(z+1)) to said encrypted data (S104, S604), said data (PF(z+1)) indicating a result of said encrypting calculated as the step of encrypting effects said encrypting, wherein said data indicating said result of said encrypting is falsification detecting data (308, BDk) for detecting whether said encrypted data is falsified data.

2. The method of claim 1, wherein the step of encrypting includes the steps of:

sequentially extracting data (Di) of portions of said data to be encrypted; and

using a result of encrypting said data of said portion previously extracted at the step of extracting to sequentially calculate a result of said encrypting said data of said portion currently extracted at the step of extracting, and using said results of said encrypting sequentially calculated to generate encrypted data (305) (S102), wherein said data indicating said result of said encrypting indicates said result of said encrypting finally calculated at the step of using (PF(z+1)).

3. The method of claim 1, wherein:

the step of encrypting includes the step of encrypting said data to be encrypted for each data block (Bk) of a predetermined size to generate encrypted block data (CBk) corresponding to said data block; and

the step of attaching includes the step of correlating data (BDk) to said encrypted block data corresponding to said data block, said data (BDk) indicating said result of said encrypting for each said data block calculated as the step of encrypting effects said encrypting.

4. The method of claim 1, wherein said data indicating said result of said encrypting is a message digest corresponding to said result of said encrypting indicated by said data indicating said result of said encrypting.

5. The method of claim 1, wherein said result of said encrypting is an entirety or a portion of an encryption parameter (401, 501) used in a common-key encryption system.

6. A method of detecting whether encrypted data is falsified, comprising the steps of:

receiving encrypted data (305) (S201); and

decrypting said encrypted data received at the step of receiving to generate decrypted data (307) (S202), wherein as the step of decrypting effects said decrypting, a result of said decrypting is calculated, and said result of said decrypting is indicated by data (DF(z+1)) representing falsification detecting data (309) for detecting whether said encrypted data is falsified data.

7. The method of claim 6, wherein said step of decrypting includes:

sequentially extracting data (Ci) of portions of said encrypted data received at the step of receiving; and

using a result of decrypting said data of said portion previously extracted at the step of extracting to sequentially calculate a result of said decrypting said data of said portion currently extracted at the step of extracting, and using said results of said decrypting sequentially calculated to generate decrypted data (S202), wherein said data indicating said result of said decrypting indicates said result of said decrypting finally calculated at the step of using (DF(z+1)).

8. The method of claim 6, further comprising the step of comparing said data of said result of said decrypting with falsification detecting data previously attached to said encrypted data to detect from a resultant comparison whether said encrypted data is falsified data (S204).

9. The method of claim 8, wherein:

the step of decrypting includes the step of decrypting said encrypted data for each data block (CBk) of a predetermined size to generate decrypted block data corresponding to said data block; and

the step of comparing includes the step of comparing said data indicating said result of said decrypting corresponding to said decrypted block data calculated in generating said decrypted block data at the step of decrypting said encrypted data for each data block, with falsification detecting data (BDk) previously attached to said data block corresponding to said decrypted block data, and detecting from a resultant comparison whether said encrypted data is falsified data (S704).

10. The method of claim 6, wherein said data indicating said result of said decrypting is a message digest corresponding to said result of said decrypting indicated by said data indicating said result of said decrypting.

11. The method of claim 6, wherein said result of said decrypting is an entirety or a portion of an encryption parameter (401) used in a common-key encryption system.

12. A method of reproducing encrypted data, comprising the steps of:

sequentially extracting portions of said encrypted data from prescribed ones of a plurality of blocks dividing said encrypted data (S1301);

using a result of decrypting said data of said portion previously extracted at the step of extracting to sequentially calculate a result of said decrypting said data of said portion currently extracted at the step of extracting, and using said results of said decrypting sequentially calculated to generate decrypted data (S1302, S1303); and

comparing said data indicating said result of said decrypting finally calculated at the step of using, with falsification detecting data previously correlated to said prescribed block for detecting whether said prescribed block is falsified, to determine from a resultant comparison whether to reproduce said decrypted data corresponding to said prescribed block generated at the step of using (S1304).

13. The method of claim 12, further comprising the step of selecting from said plurality of blocks of said encrypted data one or more blocks corresponding to said prescribed blocks, respectively, wherein said encrypted data is data obtained by encrypting content to be reproduced and the step of selecting selects said one or more blocks corresponding to a data size corresponding to an amount of said content reproducible at a time.

14. The method of claim 12, wherein said data indicating said result of said decrypting is a message digest corresponding to said result of said decrypting indicated by said data indicating said result of said decrypting.

15. The method of claim 12, wherein said result of said decrypting is an entirety or a portion of an encryption parameter (401) used in a common-key encryption system.

16. The method of claim 12, further comprising the step of obtaining said encrypted data (S1301, S1306), wherein if in the step of comparing, a decision is made that said prescribed block is not reproduced, then in the step of obtaining, said encrypted data corresponding to said prescribed block is obtained.

17. A method of communicating encrypted data, comprising the steps of:

receiving encrypted data by means of communication, said encrypted data being previously divided into a plurality of blocks (S1301, S1306);

sequentially extracting portions of said encrypted data received at the step of receiving, from prescribed ones of said plurality of blocks;

using a result of decrypting said data of said portion previously English Translation of Annexes (Substitute Pages) extracted at the step of extracting to sequentially calculate a result of said decrypting said data of said portion currently extracted at the step of extracting, and using said results of said decrypting sequentially calculated to generate decrypted data (S1302); and

comparing said data indicating said result of said decrypting finally calculated at the step of using, with falsification detecting data previously correlated to said prescribed block for detecting whether said prescribed block is falsified, to detect from a resultant comparison an error introduced in said communication of said encrypted data (S1304).

18. An encryption apparatus comprising:

means for encrypting (806) data to be encrypted (301, Bk) to generate encrypted data (305, CBk);

means for attaching (806) to said encrypted data data (PF(z+1)) indicating a result of said encrypting calculated as said means for encrypting effects said encrypting, wherein said data indicating said result of said encrypting represents falsification detecting data (308, BDk) for detecting whether said encrypted data is falsified data.

19. An apparatus detecting falsification of encrypted data, comprising:

means for receiving (810) encrypted data (305); and

means receiving said encrypted data from said means for receiving, for decrypting (813) said encrypted data to generate decrypted data (307), wherein as said means for decrypting effects said encrypting, a result of said encrypting is calculated, and said result is indicated by data (DF(z+1)) representing falsification detecting data (309) for detecting whether said encrypted data is falsified data.

20. (Amended) An apparatus of reproducing encrypted data, comprising:

means for sequentially extracting portions of encrypted data from prescribed ones of a plurality of blocks dividing said encrypted data;

English Translation of Annexes (Substitute Pages)

means using a result of decrypting said data of said portion previously extracted by said means for extracting, for sequentially calculating a result of said decrypting said data of said portion currently extracted by said means for extracting, and generating decrypted data from said results of said decrypting sequentially calculated and

means for comparing said data indicating said result of said decrypting finally calculated by said means for sequentially calculating, with falsification detecting data previously correlated to said prescribed block for detecting whether said prescribed block is falsified, to determine from a resultant comparison whether to reproduce said decrypted data corresponding to said prescribed block generated by said means for sequentially calculating.

21. (Amended) An apparatus of communicating encrypted data, comprising:

means for receiving (810) encrypted data by means of communication, said encrypted data being previously divided into a plurality of blocks;

means for sequentially extracting portions of said encrypted data received by said means for receiving, from prescribed ones of said plurality of blocks;

means (813) for using a result of decrypting said data of said portion previously extracted by said means for sequentially extracting, for sequentially calculating a result of said decrypting said data of said portion currently extracted by said means for sequentially extracting, and generating decrypted data from said results of said decrypting sequentially calculated and

means for comparing said data indicating said result of said decrypting finally calculated by said means for sequentially calculating, with falsification detecting data previously correlated to said prescribed block for detecting whether said prescribed block is falsified, to detect from a resultant comparison an error introduced in said communication of said encrypted data.

22. A program for causing a computer to perform a method of encryption, the method including the steps of:

encrypting data to be encrypted (301, Bk) to generate encrypted data (305, CBk) (S102, S602); and

attaching data (PF(z+1)) to said encrypted data (S104, S604), said data (PF(z+1)) indicating a result of said encrypting calculated as the step of encrypting effects said encrypting, wherein said data indicating said result of said encrypting is falsification detecting data (308, BDk) for detecting whether said encrypted data is falsified data.

23. A program for causing a computer to perform a method of detecting falsification of encrypted data, the method including the steps of:

receiving encrypted data (305) (S201); and

decrypting said encrypted data received at the step of receiving to generate decrypted data (307) (S202), wherein as the step of decrypting effects said decrypting, a result of said decrypting is calculated, and said result of said decrypting is indicated by data (DF(z+1)) representing falsification detecting data (309) for detecting whether said encrypted data is falsified data.

24. A program for causing a computer to perform a method of reproducing encrypted data (305), the method including the steps of:

sequentially extracting portions of said encrypted data from prescribed ones of a plurality of blocks dividing said encrypted data (S1301);

using a result of decrypting said data of said portion previously extracted at the step of extracting to sequentially calculate a result of said decrypting said data of said portion currently extracted at the step of extracting, and using said results of said decrypting sequentially calculated to generate decrypted data (S1302, S1303); and

comparing said data indicating said result of said decrypting finally calculated at the step of using, with falsification detecting data previously correlated to said prescribed block for detecting whether said prescribed block is falsified, to determine from a resultant comparison whether to reproduce said decrypted data corresponding to said prescribed block generated at the step of using (S1304).

25. A program for causing a computer to perform a method of communicating encrypted data (305) the method including the steps of:

receiving encrypted data by means of communication, said encrypted data being previously divided into a plurality of blocks (S1301, S1306);

sequentially extracting portions of said encrypted data received at the step of receiving, from prescribed ones of said plurality of blocks;

using a result of decrypting said data of said portion previously extracted at the step of extracting to sequentially calculate a result of said decrypting said data of said portion currently extracted at the step of extracting, and using said results of said decrypting sequentially calculated to generate decrypted data (S1302); and

comparing said data indicating said result of said decrypting finally calculated at the step of using, with falsification detecting data previously correlated to said prescribed block for detecting whether said prescribed block is falsified, to detect from a resultant comparison an error introduced in said communication of said encrypted data (S1304).

26. A machine readable recording medium having a program recorded therein for causing a computer to perform a method of encryption, the method including the steps of:

encrypting data to be encrypted (301, Bk) to generate encrypted data (305, CBk) (S102, S602); and

attaching data (PF(z+1)) to said encrypted data (S104, S604), said data (PF(z+1)) indicating a result of said encrypting calculated as the step of encrypting effects said encrypting, wherein said data indicating said result of said encrypting is falsification detecting data (308, BDk) for detecting whether said encrypted data is falsified data.

27. A machine readable recording medium having a program recorded therein for causing a computer to perform a method of detecting whether encrypted data (305) is falsified, the method including the steps of:

receiving encrypted data (305) (S201); and

decrypting said encrypted data received at the step of receiving to generate decrypted data (307) (S202), wherein as the step of decrypting effects said decrypting, a result of said decrypting is calculated, and said result of said decrypting is indicated by data (DF(z+1)) representing falsification detecting data (309) for detecting whether said encrypted data is falsified data.

28. A machine readable recording medium having a program recorded therein for causing a computer to perform a method of reproducing encrypted data (305), the method including the steps of:

sequentially extracting portions of said encrypted data from prescribed ones of a plurality of blocks dividing said encrypted data (S1301);

using a result of decrypting said data of said portion previously extracted at the step of extracting to sequentially calculate a result of said decrypting said data of said portion currently extracted at the step of extracting, and using said results of said decrypting sequentially calculated to generate decrypted data (S1302, S1303); and

comparing said data indicating said result of said decrypting finally calculated at the step of using, with falsification detecting data previously correlated to said prescribed block for detecting whether said prescribed block is falsified, to determine from a resultant comparison whether to reproduce said decrypted data corresponding to said prescribed block generated at the step of using (S1304).

29. A machine readable recording medium having a program recorded therein for causing a computer to perform a method of communicating encrypted data (305), the method including the steps of:

receiving encrypted data by means of communication, said encrypted data being previously divided into a plurality of blocks (S1301, S1306);

sequentially extracting portions of said encrypted data received at the step of receiving, from prescribed ones of said plurality of blocks;

using a result of decrypting said data of said portion previously extracted at the step of extracting to sequentially calculate a result of said decrypting said data of said portion currently extracted at the step of extracting, and using said results of said decrypting sequentially calculated to generate decrypted data (S1302); and

comparing said data indicating said result of said decrypting finally calculated at the step of using, with falsification detecting data previously correlated to said prescribed block for detecting whether said prescribed block is falsified, to detect from a resultant comparison an error introduced in said communication of said encrypted data (S1304).