Verifying digital signature based on shared knowledge

• US 7,936,869 B2
• Filed: 08/08/2005
• Issued: 05/03/2011
• Est. Priority Date: 01/07/2005
• Status: Active Grant

• Current Assignee: First Data Corporation (Fiserv Incorporated)
• Original Assignee: First Data Corporation (Fiserv Incorporated)
• Inventors: Beeson, Curtis Linn
• Primary Examiner(s): Smithers; Matthew B
• Assistant Examiner(s): Fields; Courtney D
• Application Number:
  US11/161,558
• Publication Number:
  US 20060153366A1
• Time in Patent Office: 2,094 Days
• Field of Search: 380/30, 380/282, 713/176, 705/67
• US Class Current: 380/30
• CPC Class Codes: G06Q 20/3674 involving authentication
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/3066 involving algebraic varieties, e.g. elliptic or hyper-elliptic curves
• CPC Class Codes: H04L 9/321 involving a third party or a trusted authority
• CPC Class Codes: H04L 9/3252 using DSA or related signature schemes, e.g. elliptic based signatures, ElGamal or Schnorr schemes

Abstract

A method of verifying a digital signature of a first party that was generated using an elliptic curve digital signature algorithm (ECDSA) includes the steps of receiving a public key from the first party; receiving a digital signature from the first party, the digital signature being for an electronic message; identifying domain parameters of an elliptic curve used in elliptic curve cryptography, including identifying a generating point of the elliptic curve; transforming the identified generating point into a second generating point as a deterministic function of shared knowledge known to and between the first party and a second party; and verifying the received digital signature as a deterministic function of the received public key, the electronic message, and the identified domain parameters, in which the second generating point is substituted for the identified generating point.

Claims

1. A method of verifying, by a second party, a digital signature of a first party that was generated using an elliptic curve digital signature algorithm, the method comprising:

(a) receiving a public key from the first party,

(b) receiving a digital signature from the first party, the digital signature being for an electronic message;

(c) identifying domain parameters of an elliptic curve used in elliptic curve cryptography, including identifying a generating point of the elliptic curve;

(d) transforming said identified generating point of said (c) into a second generating point as a deterministic function of shared knowledge known to the first party and the second party; and

(e) verifying, by the second party, said received digital signature as a function of said received public key, the electronic message, and said identified domain parameters of said (c), in which the second generating point of said (d) is substituted for said identified generating point of said (c),

wherein the above steps are performed by at least one computer processor.

2. The method of claim 1, wherein said (d) and said (e) are performed within a computer system of the second party.

3. The method of claim 2, further comprising clearing from the computer system the second generating point following said verifying the digital signature so that the second generating point is no longer available within the computer system for verifying a digital signature.

4. The method of claim 1, wherein transforming said identified generating point of said (c) into the second generating point of said (d) includes generating a transformer as a deterministic function of the shared knowledge, said generated transformer comprising a large integer value.

5. The method of claim 4, wherein said transforming said identified generating point of said (c) into the second generating point of said (d) further includes multiplying said identified generating point of said (c) by the transformer to arrive at the second generating point.

6. The method of claim 1, wherein the shared knowledge comprises an account number for an account of the first party that is maintained with the second party, and wherein the second party communicates the shared knowledge as being the account number to the first party.

7. The method of claim 1, wherein the shared knowledge comprises particular information that is known to the first party, and wherein the first party communicates the shared knowledge to the second party.

8. The method of claim 1, wherein the shared knowledge comprises information that is communicated between the first party and the second party.

9. The method of claim 1, wherein the shared knowledge comprises a secret that is shared between the first party and the second party.

10. The method of claim 1, wherein the shared knowledge comprises information that is communicated by a third party both to the first party and the second party.

11. The method of claim 1, wherein the shared knowledge comprises a unique identifier of the first party to the second party.

12. The method of claim 1, wherein the shared knowledge comprises a deterministic function of one or more predefined arguments, wherein the deterministic function and predefined arguments are known both to the first party and the second party, whereby both the first party and the second party may independently calculate the shared knowledge for use in generating the transformer.

13. The method of claim 1, wherein said identifying the domain parameters of an elliptic curve comprises receiving an identification of the domain parameters from the first party.

14. In a method of verifying a digital signature of a first party by a second party as a function of a public key, an electronic message, and domain parameters of an elliptic curve, including a generating point of the curve, wherein the digital signature was generated with an elliptic curve digital signature algorithm, an improvement to the method characterized by,

(a) calculating a larger integer value as a deterministic function of shared knowledge that is known to the first party and the second party,

(b) transforming the generating point of the domain parameters into a new generating point by multiplying the generating point of the domain parameters by said calculated integer value to obtain the new generating point, and

(c) replacing the generating point of the domain parameters with the new generating point in said step of verifying the digital signature as a function of the public key, electronic message, and the domain parameters,

wherein the above steps are performed by one or more computer processors.