Encryption/decryption appararus

• US 20070071235A1
• Filed: 08/29/2006
• Published: 03/29/2007
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshia
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Fujisaki, Koichi, Shimbo, Atsushi, Shimizu, Hideo
• Granted Patent: US 8,023,643 B2
• Time in Patent Office: Days
• US Class Current: 380/28
• CPC Class Codes: H04L 2209/046 of operations, operands or results of the operations
• CPC Class Codes: H04L 2209/08 Randomization, e.g. dummy operations or using noise
• 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]

Abstract

A first Exclusive OR circuit operates an Exclusive OR between input data and a predetermined random number. An operation circuit performs one operation of encryption and decryption of output data from the first Exclusive OR circuit. A data register circuit, which has a plurality of data hold units, holds data from the operation circuit in one data hold unit of the plurality of data hold units in response to a selection signal, and supplies the data from the one data hold unit to the operation circuit. A second Exclusive OR circuit performs an Exclusive OR between output data from the data register circuit and the random number. The operation circuit recursively performs the one operation of the data from the data register circuit and outputs next data to the data register circuit.

Claims

1. An encryption/decryption apparatus comprising:

a random number supply unit configured to supply a random number;

a first Exclusive OR circuit configured to perform an Exclusive OR between input data and the random number;

an operation circuit configured to perform one operation of encryption and decryption of output data from the first Exclusive OR circuit;

a data register circuit having a plurality of data hold units, configured to hold data from the operation circuit in one data hold unit of the plurality of data hold units in response to a selection signal, and to supply the data from the one data hold unit to the operation circuit; and

a second Exclusive OR circuit configured to perform an Exclusive OR between output data from the data register circuit and the random number;

wherein the operation circuit recursively performs the one operation of the data from the data register circuit and outputs next data to the data register circuit.

2. The encryption/decryption apparatus according to claim 1,

wherein the plurality of data hold units is two data hold units.

3. The encryption/decryption apparatus according to claim 1,

wherein the plurality of data hold units is equal to or more than three data hold units.

4. The encryption/decryption apparatus according to claim 1,

wherein the random number supply unit includes a random number generator configured to repeatedly generate a random number of which length is shorter than the input data, and a random number hold unit configured to connect a plurality of random numbers from the random number generator and to fixedly hold the random number of which length is equal to the input data.

5. The encryption/decryption apparatus according to claim 1,

wherein the operation circuit executes operation processing of the output data from the first Exclusive OR circuit at the first operation time, and executes the operation processing of previous operated data from the second operation time.

6. The encryption/decryption apparatus according to claim 5,

wherein the random number supply unit fixedly supplies the random number before the first operation time.

7. The encryption/decryption apparatus according to claim 1,

wherein the first Exclusive OR circuit is included in the operation circuit.

8. The encryption/decryption apparatus according to claim 1,

further comprising:

a selection signal generation unit configured to repeatedly generate the selection signal in synchronization with input timing of the data from the operation circuit to the register circuit.

9. The encryption/decryption apparatus according to claim 8,

wherein the data register circuit holds the data in one data hold unit selected by the selection signal whenever the data is input from the operation circuit.

10. The encryption/decryption apparatus according to claim 9,

wherein the data register circuit recursively supplies the data from the one data hold unit to the operation circuit at each operation time while an operation completion signal from the operation circuit is not received.

11. The encryption/decryption apparatus according to claim 10,

wherein the data register circuit outputs the data from the one data hold unit to the second Exclusive OR circuit in response to the operation completion signal.

12. The encryption/decryption apparatus according to claim 11,

wherein the second Exclusive OR circuit outputs an operation result of Exclusive OR between the data and the random number to the outside.

13. The encryption/decryption apparatus according to claim 1,

wherein, if the input text data is plain text data, the operation circuit operates encryption of the plain text data and outputs cipher text data as an encryption result.

14. The encryption/decryption apparatus according to claim 1,

wherein, if the input text data is cipher text data, the operation circuit operates decryption of the cipher text data and outputs plain text data as a decryption result.

15. The encryption/decryption apparatus according to claim 1,

wherein the selection signal does not continually indicate the same data hold unit in the plurality of data hold units.

16. The encryption/decryption apparatus according to claim 1,

wherein the data register circuit resets contents of another data hold unit not selected by the selection signal in the plurality of data hold units.

17. The encryption/decryption apparatus according to claim 1,

wherein the data register circuit reverses contents of another data hold unit not selected by the selection signal in the plurality of data hold units.

18. The encryption/decryption apparatus according to claim 1,

wherein the data register circuit rewrites contents of another data hold unit not selected by the selection signal with predetermined binary data or a random number.

19. An encryption/decryption apparatus comprising:

an operation circuit configured to perform one operation of encryption and decryption of input data;

a data register circuit having a plurality of data hold units, configured to hold data from the operation circuit in one data hold unit of the plurality of data hold units in response to a selection signal, and to supply the data from the one data hold unit to the operation circuit;

wherein the operation circuit recursively performs the one operation of the data from the data register circuit and outputs next data to the data register circuit.

20. The encryption/decryption apparatus according to claim 19,

further comprising:

a first Exclusive OR circuit configured to perform an Exclusive OR between the input data and a predetermined random number; and

a second Exclusive OR circuit configured to perform an Exclusive OR between output data from the data register circuit and the predetermined random number.