Apparatus and method of generating falsification detecting data of encrypted data in the course of process

• US 7,751,556 B2
• Filed: 07/10/2002
• Issued: 07/06/2010
• Est. Priority Date: 07/17/2001
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Sato, Katsuhiko, Sawada, Yuji
• Primary Examiner(s): COLIN, CARL G
• Application Number:
  US10/483,625
• Publication Number:
  US 20040172543A1
• Time in Patent Office: 2,918 Days
• Field of Search: 380/28, 380/29, 380/37, 380/42, 713/153, 713/155, 713/166, 713/168
• US Class Current: 380/28
• 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, performed by an encryption apparatus having a processing unit, comprising the steps of:

encrypting data by an encryption process, performed by the processing unit, to generate ciphertext, modifying a parameter using said ciphertext further encrypting said data using said modified parameter as encryption process information to generate further ciphertext;

attaching said encryption process information to said further ciphertext;

transmitting, by said encryption apparatus, said further ciphertext and said attached encryption process information in order to detect whether said further ciphertext is falsified data based on said encryption process information.

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

sequentially extracting portions of said data to be encrypted;

for each portion of said data in sequence, using a result of encrypting said portion previously extracted to calculate a result of encrypting said portion currently extracted, and using said sequentially calculated results of said encrypting to generate encrypted data; and

calculating said parameter based on a final of said sequentially calculated results after all portions of said data are encrypted.

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 of a predetermined size to generate encrypted block data corresponding to said data block; and

the step of attaching includes the step of correlating data to said encrypted block data corresponding to each said data block, said correlated data is said parameter calculated during said encryption for each said data block.

4. The method of claim 1, wherein said encryption process information is a message digest corresponding to said parameter calculated during said encryption.

5. The method of claim 1, wherein said parameter calculated during said encryption is an entirety or a portion of an encryption parameter used in a common-key encryption system.

6. A method of detecting whether encrypted data is falsified, performed by a decryption apparatus having a processing unit, comprising the steps of:

said decryption apparatus receiving encrypted data;

decrypting, by said processing unit, said received encrypted data based on a decryption process to generate decrypted data, including modifying a parameter using said encrypted data, said modified parameter being decrypted data falsification detecting data for detecting whether said encrypted data is falsified data; and

said processing unit comparing said decrypted data falsification detecting data with encrypted data falsification detecting data previously attached to said encrypted data to detect from a resultant comparison whether said encrypted data is falsified data.

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

sequentially extracting portions of said encrypted data received at the step of receiving;

for each portion of said data in sequence, using a result of decrypting said portion previously extracted to calculate a result of decrypting said portion currently extracted, and using said sequentially calculated results of said decrypting to generate decrypted data; and

modifying said parameter based on a final of said sequentially calculated results after all portions of said data are decrypted.

8. The method of claim 6, wherein:

the step of decrypting includes the step of decrypting said encrypted data for each data block 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 decrypted data falsification detecting 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 encrypted data falsification detecting data 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.

9. The method of claim 6, wherein said decryption process information is a message digest corresponding to said parameter calculated during said decryption.

10. The method of claim 6, wherein said parameter is an entirety or a portion of an encryption parameter used in a common-key encryption system.

11. A method of reproducing encrypted data, performed by an apparatus having a processing unit, comprising the steps of:

said processing unit sequentially extracting and decrypting portions of said encrypted data from prescribed ones of a plurality of blocks dividing said encrypted data;

said step of sequentially extracting and decrypting comprising, for each portion of said encrypted data in sequence, modifying a parameter for decrypting said encrypted data using a respective portion of said encrypted data, using a parameter determined based on said portion previously extracted to modify the parameter based on said portion currently extracted, and using said sequentially modified parameters of said decrypting to generate decrypted data from each said portion of said encrypted data, wherein a last said sequentially modified parameter is a final modified parameter after all portions of said encrypted data are decrypted; and

said processing unit comparing said final modified parameter 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.

12. The method of claim 11, 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.

13. The method of claim 11, wherein said final modified parameter is a message digest.

14. The method of claim 11, wherein said final modified parameter is an entirety or a portion of an encryption parameter used in a common-key encryption system.

15. The method of claim 11, further comprising the step of obtaining said encrypted data, 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.

16. A method of communicating encrypted data, performed by an apparatus having a processing unit, comprising the steps of:

said apparatus receiving encrypted data by means of communication, said encrypted data being previously divided into a plurality of blocks;

sequentially extracting and decrypting portions of said received encrypted data, by said processing unit, from prescribed ones of said plurality of blocks;

said step of extracting and decrypting comprising, for each portion of said encrypted data in sequence, modifying a parameter for decrypting said respective portion of said encrypted data using said respective portion of said encrypted data, using a previously modified parameter to modify the parameter based on said decrypting said portion currently extracted, and using said sequentially modified parameter to generate decrypted data from each said portion of said encrypted data, wherein a last said sequentially modified parameter is a final modified parameter after all portions of said encrypted data are decrypted; and

said processing unit comparing said final modified parameter 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.

17. An encryption apparatus comprising:

means for encrypting data by an encryption process to generate ciphertext, modifying a parameter using said ciphertext further encrypting said data using said modified parameter as encryption process information to generate further ciphertext;

means for attaching said encryption process information to said ciphertext and for transmitting said further ciphertext and said encryption process information in order to detect whether said further ciphertext is falsified data.

18. An apparatus for detecting falsification of encrypted data, comprising:

means for receiving encrypted data;

means, receiving said encrypted data from said means for receiving, for decrypting said received encrypted data based on a decryption process to generate decrypted data, including modifying a parameter using said encrypted data, said modified parameter being decrypted data falsification detecting data for detecting whether said encrypted data is falsified data; and

means for comparing said decrypted data falsification detecting data with encrypted data falsification detecting data previously attached to said encrypted data to detect from a resultant comparison whether said encrypted data is falsified data.

19. An apparatus for reproducing encrypted data, comprising:

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

said means for sequentially extracting and decrypting comprising, for each portion of said encrypted data in sequence, modifying a parameter for decrypting said encrypted data using a respective portion of said encrypted data,

means, using a parameter determined based on said portion previously extracted, for modifying the parameter based on said portion currently extracted, and generating decrypted data from said sequentially modified parameters of said decrypting and from each said portion of said encrypted data, wherein a last said sequentially modified parameter is a final modified parameter after all portions of said encrypted data are decrypted; and

means for comparing final modified parameter by said means for sequentially modifying, 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.

20. An apparatus for communicating encrypted data, comprising:

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

means for sequentially extracting and decrypting portions of said received encrypted data from prescribed ones of said plurality of blocks,

said means for sequentially extracting and decrypting comprising, for each portion of said encrypted data in sequence, modifying a parameter for decrypting said respective portion of said encrypted data,

means, using a previously modified parameter, for modifying the parameter based on said portion of encrypted data currently extracted, and generating decrypted data from said sequentially modified parameter and from each said portion of said encrypted data, wherein a last said sequentially modified parameter is a final modified parameter after all portions of said encrypted data are decrypted; and

means for comparing said final modified parameter by said means for sequentially modifying, 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.

21. 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 by an encryption process to generate ciphertext, modifying a parameter using said ciphertext, further encrypting said data using said modified parameter as encryption process information to generate further ciphertext; and

attaching said encryption process information to said further ciphertext and transmitting said further ciphertext and said attached encryption process information in order to detect whether said further ciphertext is falsified data.

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

receiving encrypted data;

decrypting said received encrypted data based on a decryption process to generate decrypted data, including modifying a parameter using said encrypted data, said modified parameter being decrypted data falsification detecting data for detecting whether said encrypted data is falsified data; and

comparing said decrypted data falsification detecting data with encrypted data falsification detecting data previously attached to said encrypted data to detect from a resultant comparison whether said encrypted data is falsified data.

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

sequentially extracting and decrypting portions of said encrypted data from prescribed ones of a plurality of blocks dividing said encrypted data,

said step of sequentially extracting and decrypting comprising, for each portion of said encrypted data in sequence, modifying a parameter for decrypting said encrypted data using a respective portion of said encrypted data, using a parameter determined based on said portion previously extracted to modify the parameter based on said portion currently extracted, and using said sequentially modified parameters of said decrypting to generate decrypted data from each said portion of said encrypted data, wherein a last said sequentially modified parameter is a final modified parameter after all portions of said encrypted data are decrypted; and

comparing said final modified parameter 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.

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

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

sequentially extracting and decrypting portions of said received encrypted data, from prescribed ones of said plurality of blocks;

said step of extracting and decrypting comprising, for each portion of said encrypted data in sequence, modifying a parameter for decrypting said respective portion of said encrypted data using said respective portion of said encrypted data, using a previously modified parameter to modify the parameter based on said decrypting said portion currently extracted, and using said sequentially modified parameter to generate decrypted data from each said portion of said encrypted data, wherein a last said sequentially modified parameter is a final modified parameter after all portions of said encrypted data are decrypted; and

comparing said final modified parameter 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.