ID-based Ring Signature and Proxy Ring Signature Schemes from Bilinear Pairings

In 2001, Rivest et al. firstly introduced the concept of ring signatures. A ring signature is a simplified group signature without any manager. It protects the anonymity of a signer. The first scheme proposed by Rivest et al. was based on RSA cryptosystem and certificate based public key setting. The first ring signature scheme based on DLP was proposed by Abe, Ohkubo, and Suzuki. Their scheme is also based on the general certificate-based public key setting too. In 2002, Zhang and Kim proposed a new ID-based ring signature scheme using pairings. Later Lin and Wu proposed a more efficient ID-based ring signature scheme. Both these schemes have some inconsistency in computational aspect. In this paper we propose a new ID-based ring signature scheme and a proxy ring signature scheme. Both the schemes are more efficient than existing one. These schemes also take care of the inconsistencies in above two schemes.Comment: Published with ePrint Archiv

Proxy Blind Signature Scheme

Blind signature is the concept to ensure anonymity of e-coins. Untracebility and unlinkability are two main properties of real coins, which require mimicking electronically. Whenever a user is permitted to spend an e-coin, he is in need to fulfill above requirements of blind signature. This paper proposes a proxy blind signature scheme with which a proxy is able to make proxy blind signature which verifier is able to verify in a way similar to proxy signature schemes

Security Analysis of A Dynamic ID-based Remote User Authentication Scheme

Since 1981, when Lamport introduced the remote user authentication scheme using table, a plenty of schemes had been proposed with table and without table using. Recently Das, Saxena and Gulati have proposed A dynamic ID-based remote user authentication scheme. They claimed that their scheme is secure against ID-theft, and can resist the reply attacks, forgery attacks, and insider attacks and so on. In this paper we show that Das et al.’s scheme is completely insecure and using of this scheme is equivalent to an open server access without any password