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… (More)
– Hwang and Li proposed the first remote user authentication scheme using smart cards to solve the problems of Lamport scheme. Unfortunately, Hwang and Li's scheme has some security weaknesses. First, Chan-Chang, Shen-Lin-Hwang and then Chang-Hwang pointed out some attacks on Hwang – Li's scheme. This paper presents a new remote user authentication scheme… (More)
In this paper we proposed two identification schemes based on the root problem. The proposed schemes are secure against passive attacks assuming that the root problem (RP) is hard in braid groups.
This paper presents a directed signature scheme with the property that the signature can be verified only with the help of signer or signature receiver. We also propose its applications to share verification of signatures and to threshold cryptosystems.
Blind signature schemes enable a useful protocol that guarantee the anonymity of the participants while Signcryption offers authentication of message and confidentiality of messages at the same time and more efficiently. In this paper, we present a blind signcryption scheme that combines the functionality of blind signature and signcryption. This blind… (More)
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… (More)
— In 2000, Hwang and Li proposed a remote user authentication scheme using smart cards to solve the problems of Lamport scheme. Later, Chan-Chang, Shen-Lin-Hwang and then Chang-Hwang pointed out some attacks on Hwang – Li's scheme. In 2003, Shen, Lin and Hwang also proposed a modified scheme to remove these attacks. In the same year, Leung-Cheng-Fong-Chan… (More)
The paper proposes four new ID based strong designated verifier proxy signature (SDVPS) scheme. The schemes are formed by introducing proxy in ID based SDVS, ID based in SDVPS and ID based proxy in SDVS. We have also analyzed the security of the schemes and their computation aspects.
Anonymous signcryption is synonyms of ring signcryption which provides anonymity of the sender along with the advantages of signcryption. Multi receiver signcryption is suited for situation where a sender wants to send a message to multiple receivers in the confidential and authenticated way. This paper proposes an identity based anonymous signcryption… (More)
Mambo et al [6-7] introduced a proxy signature scheme. Neuman  extended the scheme for delegation by warrant, which was further extended by Kim et al  to partial delegation with a warrant. In this paper we propose a new type of digital proxy signature scheme in which the warrant message can be recovered from the proxy signature. In this scheme the… (More)