Extended authenticated key exchange

• US 20070033403A1
• Filed: 07/21/2005
• Published: 02/08/2007
• Est. Priority Date: 07/21/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Mityagin, Anton, Lauter, Kristin
• Granted Patent: US 7,627,760 B2
• Time in Patent Office: Days
• US Class Current: 713/171
• CPC Class Codes: H04L 9/0847 involving identity based encryption [IBE] schemes

Abstract

Extended authenticated key exchange is described. In one aspect, an identity (ID_A) of an initiator and an identity (ID_B) of a responder are determined. A first party (i.e., the initiator or the responder) computes a session key based at least on ID_A and ID_B. A second party (i.e., the initiator or the responder) that is not the first party, uses at least ID_A and ID_B to compute a corresponding session key. The initiator'"'"'s session key and the responder'"'"'s corresponding session key, if equal, provide for secure exchange of data between the initiator and the responder.

Claims

1. A computer-implemented method for extended authenticated key exchange using a mathematical group, the method comprising:

determining an identity (ID_A) of an initiator and an identity (ID_B) of a responder;

computing, by a first party, a session key based at least on ID_A and ID_B;

the first party being the initiator or the responder; and

wherein a second party that is not the first party uses at least ID_A and ID_B to compute a corresponding session key, the second party being the initiator or the responder, the session key and the corresponding session key, if equal, providing for secure exchange of data between the initiator and the responder.

2. A method as recited in claim 1, wherein the mathematical group is a subgroup of a multiplicative group of natural numbers modulo a prime number.

3. A method as recited in claim 1, wherein the mathematical group is a subgroup of the group of points on an elliptic curve.

4. A method as recited in claim 1, wherein operations to compute the session key and the corresponding session key comprise modular exponentiation.

5. A method as recited in claim 1, wherein operations to compute the session key and the corresponding session key comprise scalar multiplication in elliptic curve groups.

6. A method as recited in claim 1, wherein computing the session key further comprises hashing a function of at least an initiator ephemeral secret key, a responder ephemeral public key, an initiator long-term secret key, a responder long-term public key, ID_A, and ID_B.

7. A method as recited in claim 1, wherein computing the session key further comprises computing the session key based on a session identifier, and wherein the session identifier is for use by the responder to determine the corresponding session key.

8. A computer-implemented method for extended authenticated key exchange using a mathematical group, the method comprising:

registering, by an initiator, an identity (ID_A) of the initiator with a certificate authority;

registering, by a responder, an identity (ID_B) of the responder with the certificate authority;

computing, by the initiator and the responder, a respective session key based at least on ID_A and ID_B; and

wherein the respective session keys, if equal, provide for secure exchange of data between the initiator and the responder.

9. A method as recited in claim 8, wherein the mathematical group is a subgroup of a multiplicative group of natural numbers modulo a prime number.

10. A method as recited in claim 8, wherein the mathematical group is a subgroup of the group of points on an elliptic curve.

11. A method as recited in claim 8, wherein operations to compute the respective session keys comprise modular exponentiation.

12. A method as recited in claim 8, wherein operations to compute the respective session keys comprise scalar multiplication in an elliptic curve group.

13. A method as recited in claim 8, wherein computing the respective session keys further comprises computing the respective session key based on a session identifier.

14. A computing device for extended authenticated key exchange using a mathematical group, the computing device comprising:

determining means to determine an identity (ID_A) of an initiator and an identity (ID_B) of a responder;

computing means to compute, by a first party, a session key based at least on ID_A and ID_B;

the first party being the initiator or the responder; and

wherein a second party that is not the first party uses at least ID_A and ID_B to compute a corresponding session key, the second party being the initiator or the responder, the session key and the corresponding session key, if equal, providing for secure exchange of data between the initiator and the responder.

15. A computing device as recited in claim 14, wherein the mathematical group is a subgroup of a multiplicative group of natural numbers modulo a prime number.

16. A method as recited in claim 14, wherein the mathematical group is a subgroup of the group of points on an elliptic curve.

17. A method as recited in claim 14, wherein means to compute the session key and the corresponding session key comprise modular exponentiation.

18. A method as recited in claim 14, wherein means to compute the session key and the corresponding session key comprise scalar multiplication in elliptic curve groups.

19. A method as recited in claim 14, wherein the computing means to compute the session key further comprises hashing means to hash a function of at least an initiator ephemeral secret key, a responder ephemeral public key, an initiator long-term secret key, a responder long-term public key, ID_A, and ID_B.

20. A method as recited in claim 14, wherein the computing means to compute the session key further comprises computing means to compute the session key based on a session identifier, and wherein the session identifier is for use by the responder to determine the corresponding session key.