Method For Authenticated Communication In Dynamic Federated Environments

• US 20100037055A1
• Filed: 08/11/2008
• Published: 02/11/2010
• Est. Priority Date: 08/11/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Fazio, Nelly, Golding, Richard Andrew, Wong, Theodore Ming-Tao
• Granted Patent: US 9,130,757 B2
• Time in Patent Office: Days
• US Class Current: 713/171
• CPC Class Codes: H04L 9/085 Secret sharing or secret splitting, e.g. threshold schemes
• CPC Class Codes: H04L 9/3218 using proof of knowledge, e.g. Fiat-Shamir, GQ, Schnorr, ornon-interactive zero-knowledge proofs
• CPC Class Codes: H04L 9/3255 using group based signatures, e.g. ring or threshold signatures

Abstract

According to one embodiment of the present invention, a method for protecting authenticated communication in dynamic federated environments is provided. The method includes distributing shares of a private signature key to a group of users. When switching from an existing to a new group of users, the method includes producing a plurality of sub-shares from each of the distributed shares of existing users, with each sub-share being accompanied by a corresponding validity proof. The sub-shares from multiple existing users are combined to generate a set of shares for new users, with each new share being derived from sub-shares from multiple existing users.

Claims

1. A method comprising:

distributing shares of a private signature key to a group of users;

producing a plurality of sub-shares from each of said distributed shares, with each sub-share being accompanied by a corresponding validity proof; and

combining said sub-shares from multiple existing users at each one of a set of new users to generate a set of new shares, each said new share being derived from sub-shares from multiple users.

2. A method according to claim 1 further comprising:

determining if a minimum number of said sub-shares have been received; and

if said minimum number has been received, said new users constructing a new share using said sub-shares.

3. A method according to claim 2 further comprising verifying the validity of each share in said new set of shares.

4. A method according to claim 3 further comprising, if said verifying determines that a share in said new set shares is not valid due to a sub-share not being valid, not using said invalid sub-share in said constructing.

5. A method according to claim 3 wherein said validity proof is a non-interactive zero-knowledge validity proof.

6. A method according to claim 1 wherein each said new share includes a corresponding validity proof.

7. A method according to claim 1 further comprising:

sending said share and corresponding validity proof to a client; and

said client reconstructing said private signature key by combining said new shares and corresponding validity proofs.

8. A method according to claim 1 wherein said users are computer systems.

9. A method according to claim 1 wherein said users are individual satellites.

10. A method comprising:

distributing shares of a private key to a group of computer systems;

allowing members of said group to authenticate to at least one client that knows a public key for said group; and

redistributing shares from said group to another set of computer systems.

11. A method according to claim 10 wherein said group of computer systems comprises a dynamic federated environment.

12. A method according to claim 10 wherein said distributing comprises establishing a private/public key pair for said group.

13. A method according to claim 12 further comprising splitting said private key among the initial members of said group via and m-out-of-n threshold sharing.

14. A method according to claim 13 further comprising setting up additional parameters to use in conjunction with validity proofs to validate computations carried out by said allowing and said redistributing.

15. A method according to claim 10 further comprising preventing said distributed shares and said new shares from operating together.

16. A method according to claim 15 further comprising:

each member of said group producing a validity proof that corresponds to said share produced by said member; and

each member of said group sending said share and said proof to said client.

17. A system comprising:

a plurality of computer systems, each having a share of a private signature key;

said plurality of computer systems each having a means for producing a plurality of sub-shares from each of said shares, with each sub-share being accompanied by a corresponding validity proof;

a client computer receiving said sub-shares and said corresponding validity proofs, and generating a set of new shares, each said new share being derived from sub-shares from multiple ones of said computer systems; and

said client computer redistributing said new set of shares to a new group of users.

18. A system according to claim 17 wherein said validity proof is a non-interactive zero-knowledge validity proof.

19. A computer program product for authenticating communications, said computer program product comprising:

a computer usable medium having computer usable program code embodied therewith, said computer usable program code comprising;

computer usable program code configured to;

distribute shares of a private signature key to a group of users;

produce a plurality of sub-shares from each of said distributed shares, with each sub-share being accompanied by a corresponding validity proof; and

combine said sub-shares from multiple existing users at each one of a set of new users to generate a set of new shares, each said new share being derived from sub-shares from multiple users.

20. A computer program product according to claim 19 wherein said computer usable program code is further configured to:

select a core set of users among said group of users;

said core set of users generating said sub-shares and delivering said sub-shares to said new group of users;

each user in said new group of users generating a new share from said sub-shares; and

each user in said new group of users verifying the validity of said new shares.