Abstract

. Delegation of rights is a common practice in the real world. Proxy signature schemes have been invented to delegate signing capability efficiently and transparently. In this paper, we present a new nonrepudiable proxy signature scheme. Nonrepudiation means the signature signers, both original and proxy signers, cannot falsely deny later that he generated a signature. In practice, it is important and, sometimes, necessary to have the ability to know who is the actual signer of a proxy signature for internal auditing purpose or when there is abusing of signing capability. The new nonrepudiable proxy signature scheme also has other desirable properties, such as proxy signature key generation and updating using insecure channels. We also show how to construct threshold proxy signature schemes with an example. Threshold signatures are motivated both by the need that arises in some organizations to have a group of employees agree on a given message (or a document) before signing it, as wel...

Citations

1404	How to share a secret - Shamir - 1979
309	Safeguarding cryptographic keys - Blakley - 1979
231	Threshold Cryptosystems - Desmedt, Frankel - 1989
93	Society and group oriented cryptography: A new concept - Desmedt - 1988
79	Proxy Signatures for Delegating Signing Operation - Mambo, Usada, et al. - 1996
61	Distributed provers with applications to undeniable signatures - Pedersen - 1991
46	A New Signature Scheme Based on the DSA Giving Message Recovery - Nyberg, Rueppel - 1993
45	Digital multisignatures - Boyd - 1989
25	Threshold cryptography,” European Trans - Desmedt - 1994
20	Threshold DSS signatures without a trusted party - Langford - 1996
16	New digital signature scheme Based on Discrete - Yen, Laih - 1993
11	Group oriented (t; n) digital signature scheme - Harn - 1994
9	Hidden signature schemes based on the discrete logarithm problem and related concepts - Horster, Michels, et al. - 1995
5	t, n)-threshold signature schemes based on discrete logarithm - Li, Hwang, et al. - 1995
2	selects ~ k 2 Zq , computes ~ r = g ~ k (mod p), and sends ~ r to Bob - Alice
2	randomly selects ff 2 Zq and fi 2 Z q , computes r = mg ff ~ r fi (mod p) and ~ m = rfi \Gamma1 (mod q): (b) Bob checks whether ~ m 2 Z q . If this is not the case, he goes back to step a). Otherwise, he sends ~ m to Alice - Bob
2	computes ~ s = ~ mx+ ~ k(mod q) and forwards ~ s to Bob - Alice
2	computes s = ~ sfi + ff(mod q): The pair (r; s) is a Nyberg-Rueppel signature of the message m and the above protocol is a blind signature scheme - Bob
1	Nonrepudiable Proxy Signature Schemes Based on Discrete Logarithm Problem, manuscript - Zhang - 1997