Public key encryption for groups

• US 20050152542A1
• Filed: 12/22/2004
• Published: 07/14/2005
• Est. Priority Date: 12/22/2003
• Status: Active Grant

• Current Assignee: Wells Fargo Bank NA (Wells Fargo & Company)
• Original Assignee: Wachovia Corporation (Wells Fargo & Company)
• Inventors: Zheng, Yuliang, Suarez, Luis Antonio
• Granted Patent: US 7,860,243 B2
• Time in Patent Office: Days
• US Class Current: 380/30
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 9/0833 involving conference or group key network architectures or network communication protocols for key management in group communication in a packet data network H04L63/065
• CPC Class Codes: H04L 9/302 involving the integer factorization problem, e.g. RSA or quadratic sieve [QS] schemes
• CPC Class Codes: H04L 9/3213 using tickets or tokens, e.g. Kerberos network architectures or network communication protocols for entities authentication using tickets in a packet data network H04L63/0807

Abstract

A system is comprised of a user and a group, wherein the group is comprised of a group leader and a group of M members where M is equal to or greater than one. The group leader generates a group public key and a group leader “master” private key. The group leader creates a personalized watermarked or decryption key, also referred to as an individual private key, for each group member. The individual private key uniquely identifies each group member. The group leader distributes the individual private keys to each of the group members. Each group member receives from a user a message encrypted using the group public key. Each of the group members uses its individual private key to decrypt the encrypted message sent by the user to the group.

Claims

1. A system for public key encryption for groups, the system comprising:

a user, and

a group comprised of a group leader and at least one group member, wherein the group has a single public key for the group and an individual private key for each group member.

2. The system according to claim 1, wherein the system is a computer network system.

3. The system according to claim 2, wherein the computer network system is for banking, investing, or retail services.

4. The system according to claim 1, wherein the single public key and individual private keys are generated by the group leader.

5. The system according to claim 4, wherein the single public key and individual private keys are generated using asymmetric encryption.

6. The system according to claim 5, wherein the asymmetric encryption is selected from the group consisting of RSA, Rabin, variants of RSA, and variants of Rabin.

7. The system according to claim 6, wherein the asymmetric encryption is RSA.

8. A method for public key encryption for groups, the method comprising:

generating a group public key and a group leader private key by a group leader of a group having at least one group member,

creating an individual private key for each group member by the group leader, and distributing the individual private key to each group member by the group leader.

9. The method according to claim 8, further comprising receiving by the group from a user a message encrypted using the group public key.

10. The method according to claim 9, further comprising decrypting the encrypted message sent by the user to the group by a group member using its individual private key.

11. The method according to claim 9, wherein the message is encrypted using asymmetric encryption.

12. The method according to claim 11, wherein the asymmetric encryption is selected from the group consisting of RSA, Rabin, variants of RSA, and variants of Rabin.

13. The method according to claim 12, wherein the asymmetric encryption is RSA.

14. The method according to claim 13, wherein the individual private key is created for each group member according to formula (5):

d_i=D+HASH₃₂(d, N, e, ID_i, Z) φ

(N) 

 

(5)

wherein

d_i is the individual private key for group member i where i equals 1 to M,

M is the number of members in the group,

d is a private exponent,

e is a public exponent,

p is a prime number,

q is a prime number,

ID_i is the identification for group member i,

Z is a data string that is shared among all group members,

N=p*q, and

φ

(N) is=(p−

1)(q−

1).

15. The method according to claim 10, wherein the message is decrypted using asymmetric decryption.

16. The method according to claim 15, wherein the asymmetric decryption is selected from the group consisting of RSA, Rabin, variants of RSA, and variants of Rabin.

17. The method according to claim 16, wherein the asymmetric decryption is RSA.

18. The method according to claim 17, wherein the individual private key is decrypted by the group member according to formula (9):

T=C^di mod N 

 

(9)

wherein

T is the unencrypted message,

C is the encrypted message,

d_i is the individual private key for group member i where i equals 1 to M,

M is the number of members in the group,

p is a prime number,

q is a prime number, and

N=p*q.

19. A method of generating an authentication token in a system comprised of a group having a group leader and at least one group member wherein the group has a single public key and each group member has an individual private key, the method comprising:

obtaining a token,

signing the token, and

encrypting the signed token using the single public key for the group.

20. The method according to claim 19, wherein the token is signed with a digital signature.

21. The method according to claim 19, wherein the signed token is encrypted using asymmetric encryption.

22. The method according to claim 21, wherein the asymmetric encryption is selected from the group consisting of RSA, Rabin, variants of RSA, and variants of Rabin.

23. The method according to claim 22, wherein the asymmetric encryption is RSA.

24. An authentication token generated according to the method of claim 19.

25. A method of validating an authentication token, the method comprising:

obtaining an encrypted signed token having been encrypted using a single public key,

decrypting the encrypted signed token using an individual private key, and

verifying the decrypted token to confirm the authenticity of the token.

26. The method according to claim 25, wherein the encrypted signed token is decrypted using asymmetric decryption.

27. The method according to claim 26, wherein the asymmetric decryption is selected from the group consisting of RSA, Rabin, variants of RSA, and variants of Rabin.

28. The method according to claim 27, wherein the asymmetric decryption is RSA.