Granted Patent B2

US 8,621,189 · App. 12/974,051 · Granted Dec 31, 2013

Abstract

Claims (58)

1. A computing device implemented method for using a cryptographic module located within the computing device, the method comprising:

a processor of the cryptographic module:

receiving a password together with a cryptographic state identifier, the cryptographic state identifier specifying either an encryption mode or a decryption mode for the cryptographic module;

checking a data store for a cryptographic key previously recorded in association with the received password;

when the data store contains a cryptographic key previously recorded in association with the received password,

retrieving said cryptographic key; and

entering the encryption mode or the decryption mode as specified by the received cryptographic state identifier, and while in said mode, receiving data to be processed from a component of the computing device, processing said received data in accordance with said mode using said retrieved cryptographic key, and outputting the processed data; and

when the data store does not contain a cryptographic key previously recorded in association with the password,

generating a random number using a random number generator;

generating at least one cryptographic key using the generated random number; and,

recording an association of the received password and the at least one cryptographic key in the data store.

2. The method of claim 1 wherein the generating at least one cryptographic key further comprises the processor combining the generated random number with the received password as inputs to a cryptographic key generation operation to form the at least one cryptographic key.

3. The method of claim 1 wherein after generating the at least one cryptographic key, the method further comprises the processor outputting the at least one cryptographic key to a component of the computing device.

4. The method of claim 1 , further comprising, after the cryptographic module generates the at least one cryptographic key:

the processor:

entering the encryption mode or the decryption mode as specified by the received cryptographic state identifier, and while in said mode, receiving data to be processed from the component of the computing device, processing said received data in accordance with said mode using said generated at least one cryptographic key, and outputting the processed data.

5. The method of claim 1 wherein the cryptographic module is further operative to receive a kill command from the computing device and, in response to the kill command, the method further comprises the processor deleting the recorded association from the data store.

6. The method of claim 1 , further comprising, prior to checking the data store:

determining whether the received password is correct; and

when the received password is not correct, the cryptographic module deleting at least one previously recorded association from the data store.

7. The method of claim 2 wherein the at least one cryptographic key is generated by combining the generated random number with the received password using an XOR operation.

8. The method of claim 2 wherein the at least one cryptographic key is generated by the processor:

deriving an elliptic curve value from the received password;

performing an elliptic curve scalar multiplication using the elliptic curve value and the generated random number; and,

applying a deterministic key-derivation function to the product of the elliptic curve scalar multiplication.

9. The method of claim 8 further comprising the processor combining the result of the deterministic key-derivation function with the generated random number using an XOR operation.

10. A cryptographic module for a computing device, the cryptographic module comprising:

an input for receiving a password together with a cryptographic state identifier, the cryptographic state identifier specifying either an encryption mode or a decryption mode for the cryptographic module;

an output for outputting data to the computing device;

a random number generator for generating a random number;

a module processor operative to:

receive the password together with the cryptographic state identifier;

check a data store for a cryptographic key previously recorded in association with the received password;

when the data store contains a cryptographic key previously recorded in association with the received password,

retrieve said cryptographic key; and

enter the encryption mode or the decryption mode as specified by the received cryptographic state identifier, and while in said mode, receive data to be processed from a component of the computing device, process said received data in accordance with said mode using said retrieved cryptographic key, and output the processed data; and

when the data store does not contain a cryptographic key recorded in association with the password,

generate a random number using the random number generator;

generate at least one cryptographic key using the generated random number; and

record an association between the received password and the at least one cryptographic key in the data store.

11. The cryptographic module of claim 10 wherein the cryptographic module is further operative to generate the at least one cryptographic key by combining the generated random number with the received password as inputs to a cryptographic key generation operation to form the at least one cryptographic key.

12. The cryptographic module of claim 10 wherein the cryptographic module is further operative to output the at least one cryptographic key to the computing device.

13. The cryptographic module of claim 10 wherein the cryptographic module is further operative to:

enter the encryption mode or decryption mode as specified by the received cryptographic state identifier, and while in said mode,

receive data to be processed from the component of the computing device;

process the received data in accordance with said mode using said generated at least one cryptographic key; and,

output the processed data.

14. The cryptographic module of claim 10 wherein the cryptographic module is further operative to receive a kill command from the computing device and, in response to the kill command, delete the recorded association from the data store.

15. The cryptographic module of claim 13 wherein the cryptographic module is further operative to:

determine whether the received password is correct; and

when the received password is not correct, delete at least one previously recorded association from the data store.

16. The cryptographic module of claim 11 wherein the cryptographic module is operative to generate the at least one cryptographic key by combining the generated random number with the received password using an XOR operation.

17. The cryptographic module of claim 11 wherein the cryptographic module is operative to generate the at least one cryptographic key by the cryptographic module:

deriving an elliptic curve value from the received password;

performing an elliptic curve scalar multiplication using the elliptic curve value and the generated random number; and,

applying a deterministic key-derivation function to the product of the elliptic curve scalar multiplication.

18. The cryptographic module of claim 17 wherein the cryptographic module is operative to generate the at least one cryptographic key by combining the result of the deterministic key-derivation function with the generated random number using an XOR operation.

19. A non-transitory computer readable storage media bearing computer readable instructions which when implemented in a processor of a cryptographic module cause the module to implement the steps of the method of claim 1 .

Assignments (8)