Public key diversification method

• US 4,944,007 A
• Filed: 06/12/1989
• Issued: 07/24/1990
• Est. Priority Date: 08/19/1988
• Status: Expired due to Term

• Current Assignee: NCR Corporation
• Original Assignee: NCR Corporation
• Inventors: Austin, Jeffrey R.
• Primary Examiner(s): Buczinski, Stephen C.
• Assistant Examiner(s): Gregory, Bernarr Earl
• Application Number:
  US07/364,949
• Time in Patent Office: 407 Days
• Field of Search: 380/21, 380/22-25, 380/30, 380/44, 380/46
• US Class Current: 713/180
• CPC Class Codes: G06Q 20/3672 initialising or reloading thereof
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 9/0877 using additional device, e.g. trusted platform module [TPM], smartcard, USB or hardware security module [HSM]
• CPC Class Codes: H04L 9/302 involving the integer factorization problem, e.g. RSA or quadratic sieve [QS] schemes
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

A method is disclosed whereby individual members of a group of members or entities may be provided, under the control of a trusted member, referred to as the parent, with respective individual secret keys for use in public key cryptography, such that the matching public key can be readily derived, and group membership authenticated. The parent initially establishes a public key (e,N) where N=P.Q is the product of two primes. In response to a request from a group member, the parent selects two further primes R,S and communicates two values dependent thereon to the requesting member, which selects two more primes T and U for use in conjunction with the received values to establish the member'"'"'s secret key.

Claims

1. A method of generating key values for use in public key cryptography by a requesting entity, including the step of generating at a parent entity, public key values N, e, where N is the product of first and second prime numbers P,Q and e is a corresponding public key integer value, comprising:

selecting, at said parent entity, third and fourth prime numbers R,S;

transmitting to said requesting entity a first value N_mi and a second value Φ

(N_mi) where said first value N_mi =N·

R·

S and where said second value Φ

(N_mi)=Φ

(N)·

(R-1)·

(S-1), wherein the symbol Φ

represents Euler'"'"'s totient function;

selecting, at said requesting entity, fifth and sixth prime numbers, T,U; and

computing, at said requesting entity, a third value N_m and a fourth value d_m, where N_m =N_mi ·

T·

U, and where d_m =[1+K Φ

(N_m)]/e;

wherein Φ

(N_m)=Φ

(N_mi)·

(T-1)·

(U-1); and

wherein K and d_m are integers, whereby d_m is adapted to be used by said requesting entity as a secret key counterpart of the public key value e with respect to N_m.

2. A method according to claim 1 wherein said parent entity includes storage means, said method further comprising:

storing the values of N, Φ

(N) and e in said storage means.

3. A method according to claim 2, further comprising:

storing in said storage means an identification code identifying said requesting entity, said first value N_mi and said second value Φ

(N_mi).

4. A method according to claim 3 wherein said requesting entity includes further storage means, said method further comprising:

computing, at said requesting entity, a fifth value N_mv, where N_mv =N_m /N; and

storing said fifth value in said further storage means.

5. A method according to claim 4, further comprising:

multiplying the value N_mv by the value N to yield the value N_m, utilization of which, with the value e, enables the verification of digital signatures.

7. A method according to claim 4, further comprising:

multiplying the value N_mv by the value N to yield the value N_m, utilization of which, with the value e, enables the enciphering of data.

8. A method according to claim 1 wherein said public key integer value e is a prime number.

6. A method according to claim 6 wherein said public key integer value e is a prime number.