Signature protocol

1. A method for generating an elliptic curve cryptographic signature, comprising a first component and a second component, for a message using a long term private key, a session private key and a session public key generated from the session private key, the method comprising:

generating a first signature component comprising adding an x co-ordinate of the session public key to a cryptographic hash of the message;

generating a second signature component comprising multiplying the long term private key and the first signature component to provide a first result, subtracting the first result from the session private key to provide a second result, and multiplying the second result with the session private key.

2. The method of claim 1 , wherein the signature may be verified by:

reconstructing the session public key from the signature components, a long term public key corresponding to the long term private key, and a base point generator;

recovering the x co-ordinate of the reconstructed session public key;

generating an intermediate component from the first signature component and the message; and

verifying the signature by comparing the intermediate component and the recovered x co-ordinate of the session public key.

3. The method of claim 2 , wherein the intermediate component is generated as a subtraction of the hash of the message from the first signature component.

4. The method of claim 1 , wherein the first signature component is generated as the sum of the hash of the message and the x co-ordinate of the session public key.

5. The method of claim 1 , wherein combining the second result with the session private key comprises:

generating a third result from the session private key; and

combining the inverse of the third result with the second result.

6. The method of claim 5 , wherein generating the third result comprises adding one to the value of the session private key.

7. The method of claim 1 , wherein the first signature component is generated by encrypting the message with a block cipher using the x co-ordinate of the session public key as a symmetric key.

8. The method of claim 1 , wherein the first signature component is generated by applying a cryptographic hash function to the concatenation of the message and the x co-ordinate of the session public key.

9. A cryptographic correspondent device comprising a processor and a memory, the memory having stored thereon a long term private key, the device further having associated therewith a cryptographic corresponding long term public key generated using the long term private key and a cryptographic generator, and an identity, the memory further having stored thereon computer instructions which when executed by the processor cause the processor to implement a elliptic curve cryptographic signature scheme comprising:

generating a session private key and cryptographic corresponding session public key;

generating a first signature component comprising adding an x co-ordinate of the session public key to a cryptographic hash of the message; and

generating a second signature component comprising multiplying the long term private key and the first signature component to provide a first result, subtracting the first result from the session private key to provide a second result, and multiplying the second result with the session private key.

10. The device of claim 9 , wherein the signature may be verified by:

reconstructing the session public key from the signature components, a long term public key corresponding to the longer term private key, and a base point generator;

recovering the x coordinate of the reconstructed session public key;

generating an intermediate component from the first signature component and the message; and

verifying the signature by comparing the intermediate component and the recovered x co-ordinate of the session public key.

11. The device of claim 10 , wherein the intermediate component is generated as a subtraction of the hash of the message from the first signature component.

12. The device of claim 10 , wherein the first signature component is generated by encrypting the message with a block cipher using the x co-ordinate of the session public key as a symmetric key.

13. The device of claim 9 , wherein the first signature component is generated as the sum of the hash of the message and the x co-ordinate of the session public key.

14. The device of claim 9 , wherein the first signature component is generated by applying a cryptographic hash function to the concatenation of the message and the x co-ordinate of the session public key.

15. The device of claim 9 , wherein combining the second result with the session private key comprises

generating a third result from the session private key; and

combining the inverse of the third result with the second result.

16. The device of claim 15 , wherein generating the third result comprises adding one to the value of the session private key.