Efficient Certified Email Protocol

• US 20090094452A1
• Filed: 10/08/2007
• Published: 04/09/2009
• Est. Priority Date: 10/08/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Shao, Jun, Zhu, Bin, Feng, Min
• Granted Patent: US 8,341,410 B2
• Time in Patent Office: Days
• US Class Current: 713/151
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/0844 with user authentication or key authentication, e.g. ElGamal, MTI, MQV-Menezes-Qu-Vanstone protocol or Diffie-Hellman protocols using implicitly-certified keys
• CPC Class Codes: H04L 9/321 involving a third party or a trusted authority
• CPC Class Codes: H04L 9/3218 using proof of knowledge, e.g. Fiat-Shamir, GQ, Schnorr, ornon-interactive zero-knowledge proofs

Abstract

An exemplary optimistic protocol for a two-party transaction includes a setup sub-protocol that includes an authorized Diffie-Hellman key agreement, an exchange sub-protocol that includes sending a certificate from a sending party to a receiving party and sending a receipt from the receiving party to the sending party and a dispute sub-protocol that includes a dispute resolution mechanism for resolving disputes between the sending party and the receiving party due to sending of an invalid certificate, due to sending an invalid receipt, or due to abortion of the exchange sub-protocol. Other exemplary methods, systems, etc., are also disclosed.

Claims

1. An optimistic protocol for a two-party transaction, the optimistic protocol comprising:

a setup sub-protocol that comprises an authorized Diffie-Hellman key agreement;

an exchange sub-protocol that comprises sending a certificate from a sending party to a receiving party and sending a receipt from the receiving party to the sending party; and

a dispute sub-protocol that comprises a dispute resolution mechanism for resolving disputes between the sending party and the receiving party due to sending of an invalid certificate, due to sending an invalid receipt, or due to abortion of the exchange sub-protocol.

2. The optimistic protocol of claim 1 wherein the transaction comprises an email transaction.

3. The optimistic protocol of claim 1 wherein the exchange sub-protocol comprises sending an encrypted message with the certificate.

4. The optimistic protocol of claim 1 wherein the exchange sub-protocol comprises sending a message description with the certificate.

5. The optimistic protocol of claim 1 wherein the exchange sub-protocol further comprises sending decryption information from the sending party to the receiving party to decrypt information sent previously from the sending party to the receiving party.

6. The optimistic protocol of claim 1 wherein the exchange sub-protocol further comprises sending information from the sending party to the receiving party and comparing the information against information sent previously from the sending party to the receiving party.

7. The optimistic protocol of claim 6 wherein the comparing comprises comparing a message against a message description sent previously.

8. The optimistic protocol of claim 7 wherein an unfavorable comparison invokes the dispute sub-protocol.

9. The optimistic protocol of claim 1 wherein the dispute sub-protocol comprises a trusted third party.

10. The optimistic protocol of claim 1 wherein the authorized Diffie-Hellman key agreement comprises sharing an encryption key between a sending party and a trusted third party.

11. The optimistic protocol of claim 10 wherein the trusted third party resolves disputes between the sending party and the receiving party.

12. The optimistic protocol of claim 1 wherein the sending party and the receiving party transact via a distributed application operating in a distributed computing environment.

13. The optimistic protocol of claim 1 wherein the setup sub-protocol comprises binding a public key of the sending party to a certificate for the sending party.

14. The optimistic protocol of claim 13 wherein the exchange sub-protocol comprises sending the certificate from the sending party to the receiving party.

15. The optimistic protocol of claim 1 wherein the setup sub-protocol comprises a modified Schnorr signature scheme for generating a signature for the receiving party.

16. A method, implemented at least in part by a computing device, the method comprising:

providing a public key to a certification authority;

receiving a certificate from the certification authority that binds the public key;

sending an encrypted message and the certificate to a receiving party;

receiving a signature from the receiving party; and

in response to the receiving, sending information to the receiving party to decrypt the message.

17. The method of claim 16 further comprising sending a description of the message with the encrypted message.

18. A method, implemented at least in part by a computing device, the method comprising:

generating a signature;

receiving an encrypted message and a certificate from a sending party;

sending the signature to the sending party;

receiving information from the sending party to decrypt the message; and

decrypting the message.

19. The method of claim 18 wherein the generating the signature comprises generating a signature using a modified Schnorr signature scheme.

20. The method of claim 18 further comprising receiving a description of the message from the sending party prior to the decrypting and comparing the decrypted message against the description of the message.