Peer-to-peer contact exchange

• US 20070250700A1
• Filed: 04/21/2006
• Published: 10/25/2007
• Est. Priority Date: 04/21/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Horton, Noah, Singhal, Sandeep, Sidhu, Gursharan
• Granted Patent: US 8,086,842 B2
• Time in Patent Office: Days
• US Class Current: 713/150
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 63/0823 using certificates cryptographic mechanisms or cryptographic arrangements for entity authentication involving certificates H04L9/3263
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

A system may publish authenticated contact information in a publicly available index store, retrieve the contact information, and validate it. The claimed method and system may provide a client-based, server optional approach to publishing. The publicly available index store may be a distributed hash table used in a peer-to-peer network. The system may be used in other secure directory service applications where a server may not be available or where server trust may be minimal.

Claims

1. A method of using a publicly available index store for a secure publication system, the method comprising:

providing a cryptographically unique identifier that is statistically unique to a public key;

signing a message with a publisher private key, wherein the message includes the publisher public key;

inserting the message into a publicly available index store, where the message is indexed by the cryptographically unique identifier;

retrieving the entry based on the cryptographically unique identifier;

determining whether the cryptographically unique identifier relates to the public key; and

determining whether the message is signed by a private key corresponding to the public key.

2. The method of claim 1, further comprising determining whether the message has an expected format and syntax.

3. The method of claim 1, wherein the index store is one of a distributed hash table and a directory server.

4. The method of claim 1, wherein the cryptographically unique identifier is derived from the user public key using a hash function.

5. The method of claim 1, further comprising allowing a computer performing the retrieving to use the public key upon determining that the cryptographically unique identifier relates to the public key, that the message is signed by a private key corresponding to the public key, and that the message has an expected format and syntax.

6. The method of claim 1, wherein the message further comprises a duration parameter that is proportional to an encryption strength.

7. The method of claim 6, further comprising allowing a computer performing the retrieving to use the public key upon determining that a duration indicated by the duration parameter has not expired, that the cryptographically unique identifier relates to the public key, that the message is signed by a private key corresponding to the public key, and that the message has an expected format and syntax.

8. The method of claim 1, wherein the cryptographically unique identifier comprises a group public key.

9. The method of claim 1, wherein the cryptographically unique identifier is formed from at least a first user cryptographically unique identifier and a second user cryptographically unique identifier.

10. A computer system comprising:

a plurality of peer nodes forming a peer-to-peer network;

a distributed hash table of the peer-to-peer network;

a first peer node creating a cryptographically unique identifier that is statistically unique to a public key of the first peer node, and inserting a message, containing the public key and signed by a private key corresponding to the public key, into the distributed hash table that is indexed by the cryptographically unique identifier;

a second node retrieving the message based on the cryptographically unique identifier, determining whether the cryptographically unique identifier relates to the public key, determining whether the message is signed by the private key corresponding to the public key, and determining whether the message has an expected format and syntax.

11. The system of claim 10, wherein the second node uses the public key to communicate with the first node upon determining that the cryptographically unique identifier relates to the public key, that the signature is signed by the private key corresponding to the public key, and that the message has an expected format and syntax.

12. The system of claim 10, wherein the cryptographically unique identifier comprises a combination of a first cryptographically unique identifier associated with the first node and a second cryptographically unique identifier associated with the second node.

13. The system of claim 12, wherein the message is encrypted using a public key of the second node.

14. The system of claim 10, wherein the message comprises a duration parameter, wherein the duration parameter is proportional to the strength of an encryption algorithm used to generate the public key and the private key corresponding to the public key.

15. The system of claim 14, wherein the second node accepts the message upon determining that a duration indicated by the duration parameter has not expired, that the cryptographically unique identifier relates to the public key, that the message is signed by the private key corresponding to the public key, and that the message has an expected format and syntax.

16. A computer-readable medium having computer-executable instructions for performing operations comprising:

deriving a cryptographically unique identifier from a public key;

retrieving an entry in an index store based on the cryptographically unique identifier, wherein the entry contains a message and a public key, which together are signed by a private key corresponding to the public key;

determining whether the cryptographically unique identifier relates to the public key; and

determining whether the message and public key are signed by the private key.

17. The computer-readable medium of claim 16, further comprising determining whether the message has an expected format and syntax.

18. The computer-readable medium of claim 16, further comprising determining whether a duration parameter of the message has expired.

19. The computer-readable medium of claim 18, wherein a duration indicated by the duration parameter is proportional to a level of encryption used to generate the public and private key.

20. The computer-readable medium of claim 16, wherein the cryptographically unique identifier is formed by combining a first cryptographically unique identifier and a second cryptographically unique identifier and wherein the message is encrypted using a public key of a computer associated with the second cryptographically unique identifier.