ENCRYPTING APPARATUS FOR COMMON KEY CIPHER

• US 20090003598A1
• Filed: 11/16/2007
• Published: 01/01/2009
• Est. Priority Date: 11/16/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Itoh, Kouichi, Okada, Souichi, Takenaka, Masahiko
• Granted Patent: US 8,218,762 B2
• Time in Patent Office: Days
• US Class Current: 380/46
• CPC Class Codes: H04L 2209/046 of operations, operands or results of the operations
• CPC Class Codes: H04L 2209/12 Details relating to cryptographic hardware or logic circuitry
• CPC Class Codes: H04L 9/003 for power analysis, e.g. differential power analysis [DPA] or simple power analysis [SPA]
• CPC Class Codes: H04L 9/0631 Substitution permutation network [SPN], i.e. cipher composed of a number of stages or rounds each involving linear and nonlinear transformations, e.g. AES algorithms

Abstract

The first route selection device re-arrays a plurality of extended key mask values at random according to the value of a random number generated by a random number generation device. An extended key operation device generates an exclusive logical OR of a plurality of the re-arrayed extended key mask values, a data string representing extended key and an input data string. The second route selection device re-arrays the data string of the exclusive logical OR by performing a re-array conversely with the first route selection device according to the value of the random number. A non-linear conversion device applies non-linear conversion to the re-arrayed data string and outputs a data string masked by a plurality of non-linear conversion mask values. The third route selection device re-arrays the masked data string by performing the same re-array as the first route selection device according to the value of the random number.

Claims

1. An encrypting apparatus for performing an encryption process of a common key cipher, comprising:

a random number generation device for generating a random number;

a first route selection device for re-arraying a data string composed of a plurality of extended key mask values for masking extended keys, at random according to a value of the random number and outputting the data string;

an extended key operation device for generating an exclusive logical OR of a plurality of extended key mask values outputted from the first route selection device, a data string representing the extended keys and an input data string;

a second route selection device for re-arraying a data string of the exclusive logical OR by performing re-array conversely with the first route selection device according to the value of the random number and outputting the data string;

a non-linear conversion device for applying non-linear conversion to the data string outputted from the second route selection device and outputting a data string masked by a plurality of non-linear conversion mask values; and

a third route selection device for re-arraying the data string outputted from the non-linear conversion device by performing the same re-array as the first route selection device according to the value of the random number and outputting the data string.

2. The encrypting apparatus according to claim 1, wherein

the data string outputted from the non-linear conversion device represents an exclusive logical OR of a result of converting an exclusive logical OR of the data string outputted from the second route selection device and the plurality of extended key mask values by an unmasked non-linear conversion table and the plurality of non-linear conversion mask values.

3. The encrypting apparatus according to claim 2, wherein

the plurality of extended key mask values are different from each other and the plurality of non-linear conversion mask values are different from each other.

4. The encrypting apparatus according to claim 1, wherein

each of the first, second and third route selection devices comprises a plurality of switching devices and

each of the switching devices comprising first and second input units and first and second output units and performing one of a first switching operation of outputting data inputted to the first input unit from the first output unit and outputting data inputted to the second input unit from the second output unit, and a second switching operation of outputting data inputted to the first input unit from the second output unit and outputting data inputted to the second output unit from the first output unit according to the value of the random number.

5. The encrypting apparatus according to claim 4, wherein

the random number is composed of four values and the plurality of switching devices are composed of first, second, third and fourth switching devices each of which operates according to each of the four values of the random number,

first and second output units of the first switching device are connected to a first input unit of the third switching device and a first input unit of the fourth switching device, respectively, and first and second output units of the second switching device are connected to a second input unit of the third switching device and a second input unit of the fourth switching device, respectively, and

four pieces of data are inputted to the first and second input units of the first switching device and the first and second input units of the second switching unit, respectively, and four pieces of data are outputted from the first and second output units of the third switching device and the first and second output units of the fourth switching device, respectively.

6. The encrypting apparatus according to claim 4, wherein

the random number is composed of six values and a plurality of switching devices included in the first and third route selection devices are composed of first, second, third, fourth, fifth and six switching devices each of which operates according to each of the six values of the random number,

first and second output units of the first switching device are connected to a first input unit of the third switching device and a first input unit of the fourth switching device, respectively, and first and second output units of the second switching device are connected to a second input unit of the third switching device and a second input unit of the fourth switching device, respectively, first and second output units of the third switching device are connected to a second input unit of the sixth switching device and a first input unit of the fifth switching device, respectively, and first and second output units of the fourth switching device are connected to a second input unit of the fifth switching device and a first input unit of the sixth switching device, respectively,

four pieces of data are inputted to the first and second input units of the first switching device and the first and second input units of the second switching unit, respectively, and four pieces of data are outputted from the first and second output units of the fifth switching device and the first and second output units of the sixth switching device, respectively,

a plurality of switching devices included in the second route selection device are composed of seventh, eighth, ninth, tenth, eleventh and twelfth switching devices each of which operates according to each of the six values of the random number,

first and second output units of the seventh switching device are connected to a second input unit of the ninth switching device and a first input unit of the tenth switching device, respectively, first and second output units of the eighth switching device are connected to a second input unit of the tenth switching device and a first input unit of the ninth switching device, respectively, first and second output units of ninth switching device are connected to a first input unit of the eleventh switching device and a first input unit of the twelfth switching device, respectively, and first and second output units of the tenth switching device are connected to a second input unit of the eleventh switching device and a second input unit of the twelfth switching device, respectively, and

four pieces of data are inputted to the first and second input units of the seventh switching device and the first and second input units of the eighth switching device, respectively and four pieces of data are outputted from the first and second output units of the eleventh switching device and the first and second output units of the twelfth switching device, respectively.

7. The encrypting apparatus according to claim 1, further comprising:

a fourth route selection device for re-arraying a data string composed of a plurality of plain text mask values for masking plain text by performing the same re-array as the first route selection device according to the value of the random number;

a plain text operation device for generating an exclusive logical OR of the plurality of plain text mask values outputted from the fourth route selection device and a data string representing the plain text and outputting the exclusive logical OR to the extended key operation device as the input data string;

a first processing device for applying a shift-row process and a mix-column process to a data string outputted from the third route selection device; and

a mask operation device for generating an exclusive logical OR of a process result of the first processing device, a data string for releasing a mask of the process result of the first processing device and a plurality of new mask values, wherein

the data string outputted from the non-linear conversion device represents an exclusive logical OR of a result of converting an exclusive logical OR of the data string outputted from the second route selection device, the plurality of extended key mask values and the plurality of plain text mask values by an unmasked non-linear conversion table, and the plurality of non-linear conversion mask values, a data string of an exclusive logical OR, outputted from the mask operation device is fed back to the extended key operation device as the input data string, a loop process by the first route selection device, the extended key operation device, the second route selection device, the non-linear conversion device, the third route selection device, the first processing device and the mask operation device is repeatedly applied to each of (N−

1) extended keys from the 0th through (N−

2)th.

8. The encrypting apparatus according to claim 7, wherein

the plurality of extended key mask values are different from each other, the plurality of plain text mask values are different from each other and the plurality of non-linear conversion mask values are different from each other.

9. The encrypting apparatus according to claim 7, further comprising

a fifth route selection device for re-arraying the data string composed of the plurality of plain text mask values by performing the same re-array as the first route selection device according to the value of the random number and outputting an obtained data string to the mask operation device as the plurality of new mask values.

10. The encrypting apparatus according to claim 7, further comprising:

a sixth route selection device for re-arraying a data string composed of the plurality of non-linear conversion mask values by performing the same re-array as the first route selection device according to the value of the random number and outputting the data string; and

a second processing device for applying a shift-row process and a mix-column process to the data string outputted from the sixth route selection device and outputting an obtained process result to the mask operation device as the data string for releasing the mask.

11. The encrypting apparatus according to claim 7, further comprising:

a seventh route selection device for re-arraying a data string composed of a plurality of extended key mask values for masking (N−

1)th extended key by performing the same re-array as the first route selection device according to the value of a random number and outputting the data string;

a first operation device for generating an exclusive logical OR of the plurality of extended key mask values outputted from the seventh route selection device, a data string representing the(N−

1)th extended key and a data string of an exclusive logical OR outputted from the mask operation device in the loop process using the (N−

2)th extended key;

an eighth route selection device for re-arraying a data string of the exclusive logical OR, outputted from the first operation device by performing re-array conversely with the first selection device according to the value of the random number and outputting the data string;

a latter-stage non-linear conversion device for applying non-linear conversion to the data string outputted from the eighth route selection device and outputting a data string masked by the plurality of non-linear conversion mask values;

a ninth route selection device for re-arraying the data string outputted from the latter-stage non-linear conversion device by performing the same re-array as the first route selection device according to the value of a random number and outputting the data string;

a third processing device for applying a shift-row process to the data string outputted from the ninth route selection device;

a tenth route selection device for re-arraying a data string composed of a plurality of extended key mask values for masking Nth extended key by performing the same re-array as the first route selection device according to the value of the random number and outputting the data string;

a second operation device for generating an exclusive logical OR of the plurality of extended key mask values outputted from the tenth route selection device, a data string representing the Nth extended key and a process result of the third processing device; and

a third operation device for generating an exclusive logical OR of a data string of the exclusive logical OR, outputted from the second operation device, a data string for releasing a mask of the process result of the third processing device and a data string for releasing a mask of the Nth extended key and outputting the exclusive logical OR as cipher text, wherein

the data string outputted from the latter-stage non-linear conversion device represents an exclusive logical OR of a result of converting an exclusive logical OR of the data string outputted from the eighth route selection device, the plurality of extended key mask values for masking the (N−

1)th extended key mask values and the plurality of plain text mask values by the unmasked non-linear conversion table, and the plurality of non-linear conversion mask values.

12. The encrypting apparatus according to claim 11, further comprising

an eleventh route selection device for re-arraying the data string composed of the plurality of extended key mask values for masking the Nth extended key by performing the same re-array as the first route selection device according to the value of the random number and outputting an obtained data string to the third operation device as the data string for releasing the mask of the Nth extended key.

13. The encrypting apparatus according to claim 11, further comprising

a twelfth route selection device for re-arraying a data string composed of the plurality of non-linear conversion mask values by performing the same re-array as the first route selection device according to the value of the random number and outputting the data string;

and

a fourth processing device for applying a shift-row process to the data string outputted from the twelfth route selection device and outputting an obtained process result to the third operation device as the data string for releasing the mask of the process result of the third processing device.

14. The encrypting apparatus according to claim 11, wherein

each of the first, second, third, fourth, seventh, eighth, ninth and tenth route selection devices comprises one or more unit data string route selection devices,

the unit data string route selection device comprises a plurality of switching devices,

each switching device comprises first and second input units and first and second output units and performs one of a first switching operation of outputting data inputted to the first input unit and data inputted to the second input unit from the first and second output units, respectively, and a second operation of outputting data inputted to the first input unit and data inputted to the second input unit from the second and first output units, respectively, according to the value of the random number.

15. The encrypting apparatus according to claim 14, wherein

four different ones of a plurality of values constituting the random number are inputted to each of the one or more unit data string route selection devices,

the plurality of switching devices are composed of first, second, third and fourth switching devices each of which operates according to each of the four values of the random number,

first and second output units of the first switching device are connected to a first input unit of the third switching device and a first input unit of the fourth switching device, respectively, first and second output units of the second switching device are connected to a second input unit of the third switching device and a second input unit of the fourth switching device, respectively, and

four pieces of data are inputted to the first and second input units of the first switching device and the first and second input units of the second switching device, respectively, and four pieces of data are outputted from first and second output units of the third switching device and first and second output units of the fourth switching device, respectively.

16. The encrypting apparatus according to claim 14, wherein

six different ones of a plurality of values constituting the random number are inputted to each of the one or more unit data string route selection device,

the plurality of switching devices included in the first, third, fourth, seventh, ninth and tenth route selection devices are composed of first, second, third, fourth, fifth and sixth switching devices each of which operates according to each of the six values of the random number

first and second output units of the first switching device are connected to a first input unit of the third switching device and a first input unit of the fourth switching device, respectively, first and second output units of the second switching device are connected to a second input unit of the third switching device and a second input unit of the fourth switching device, respectively, first and second output units of the third switching device are connected to a second input unit of the sixth switching device and a first input unit of the fifth switching device, respectively, and first and second output units of the fourth switching device are connected to a second input unit of the fifth switching device and a first input unit of the sixth switching device,

four pieces of data are inputted to the first and second input units of the first switching device and the first and second input units of the second switching device, respectively, and four pieces of data are outputted from first and second output units of the fifth switching device and first and second output units of the sixth switching device, respectively,

the plurality of switching devices included in the second, and eighth route selection devices are composed of seventh, eighth, ninth, tenth, eleventh and twelfth switching devices each of which operates according to each of the six values of the random number,

first and second output units of the seventh switching device are connected to a second input of the ninth switching device and a first input of the tenth switching device, respectively, first and second output units of the eighth switching device are connected to a second input unit of the tenth switching device and a first input unit of the ninth switching device, respectively, first and second output units of the ninth switching device are connected to a first input unit of the eleventh switching device and a first input unit of the twelfth switching device, respectively, and first and second output units of the tenth switching device are connected to a second input unit of the eleventh switching device and a second input unit of the twelfth switching device, and

four pieces of data are inputted to the first and second input units of the seventh switching device and the first and second input units of the eighth switching device, respectively, and four pieces of data are outputted from first and second output units of the eleventh switching device and first and second output units of the twelfth switching device, respectively.

17. The encrypting apparatus according to claim 14, wherein

each of the first, second, third, fourth, seventh, eighth, ninth and tenth route selection devices comprises a plurality of unit data string route selection devices and a switching device for dividing a data string to be inputted to the plurality of unit data string route selection devices into two parts each composed of one or more unit data strings, changing an order of the two parts according to one of a plurality of values constituting the random number and outputting an obtained data string to the plurality of unit data string route selection devices.

18. The encrypting apparatus according to claim 14, wherein

each of the first, second, third, fourth, seventh, eighth, ninth and tenth route selection devices comprises four unit data string route selection devices and a switching device for dividing a data string to be inputted to the four unit data string route selection devices into four unit data strings, changing an order of the four unit data strings according to a part of a plurality of values constituting the random number and outputting an obtained data string to the four unit data string route selection devices.

19. An encrypting method for performing an encryption process of a common key cipher, comprising:

generating a random number;

re-arraying a data string composed of a plurality of extended key mask values for masking an extended key according to a value of the random number;

generating an exclusive logical OR of a plurality of re-arrayed extended key mask values, a data string representing the extended key and an input data string;

re-arraying a data string of the exclusive logical OR by performing a re-array conversely with the plurality of extended key mask values according to the value of the random number;

generating a data string masked with a plurality of non-linear conversion mask values by applying non-linear conversion to the re-arrayed data string; and

re-arraying the masked data string by performing the same re-array as the plurality of extended key mask values according to the value of the random number.