International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Jing XU

Publications

Year
Venue
Title
2004
EPRINT
ID-Based Proxy Signature Using Bilinear Pairings
Identity-based (ID-based) public key cryptosystem can be a good alternative for certificate-based public key setting, especially when efficient key management and moderate security are required. A proxy signature scheme permits an entity to delegate its signing rights to another entity. But to date, no ID-based proxy signature schemes with provable security have been proposed. In this paper, we formalize a notion of security for ID-based proxy signature schemes and propose a scheme based on the bilinear pairings. We show that the security of our scheme is tightly related to the computational Diffie-Hellman assumption in the random oracle model.
2004
EPRINT
Identity Based Threshold Proxy Signature
Identity-based (ID-based) public key cryptosystem can be a good alternative for certificate-based public key setting, especially when efficient key management and moderate security are required. In a $(t,n)$ threshold proxy signature scheme, the original signer delegates the power of signing messages to a designated proxy group of $n$ members. Any $t$ or more proxy signers of the group can cooperatively issue a proxy signature on behalf of the original signer, but $t-1$ or less proxy signers cannot. In this paper, we present an ID-based threshold proxy signature scheme using bilinear pairings. We show the scheme satisfies all security requirements in the random oracle model. To the best of authors' knowledge, our scheme is the first ID-based threshold proxy signature scheme.
2003
EPRINT
Attack on an Identification Scheme Based on Gap Diffie-Hellman Problem
In [KK], a new identification scheme based on the Gap Diffie-Hellman problem was proposed at SCIS 2002, and it is shown that the scheme is secure against active attacks under the Gap Diffie-Hellman Intractability Assumption. Paradoxically,this identification scheme is totally breakable under passive attacks. In this paper, we show that any adversary holding only public parameters of the scheme can convince a verifier with probability 1.