Authentication and key agreement protocol becomes an important security issue for multi-server architecture. Combining biometrics with password enhances the level of security. Recently, Baruah et al. analyzed that Mishra et al.’s protocol has several drawbacks and proposed an improved biometric based multi-server authentication scheme. They claimed that their scheme satisfies all the required s...

This paper presents the first equivalent key recovery attack on H2-MAC-MD5, which conduces to a selective forgery attack directly. H2-MAC is similar with HMAC except that the outer key is omitted. For HMAC-MD5, since the available differential paths are pseudocollisions, all the key recovery attacks are in the related-key setting, while our attack on H2MAC-MD5 gets rid of this restriction. Base...

To enhance applications of smart cards, Miyazaki and Takaragi proposed a (t, n) threshold digital signature scheme based on the security of elliptic curve discrete logarithm (ECDLP). The advantages of their scheme are low communication bandwidth and computational complexity, which provides critical benefits for the use of smart cards in distributed environments. Recently Wu et al. pointed out t...

The password-based authentication protocol is the conventional authentication protocol in many distributed systems to authenticate the remote users. However, a passwordbased protocol is vulnerable to the guessing attack, the replay attack, the stolen-verifier problem and the forgery attack [1]. These attacks bother the SAS protocol [2], the revised SAS-1 [3], the revised SAS-2 [3] and the OSPA ...

Although a great deal of research has been done on electronic cash schemes with blind multisignatures to prevent an insider attack, there is no discussion of a formal security model in the literature. Firstly we discussed the security model of e-cash schemes based on the blind multisignature scheme against a (restricted) attack model and proposed a concrete scheme proven to be secure in the mod...

In 2001, Wong and Chan proposed two mutual authentication and key exchange protocols (MAKEP) for low power wireless communications, which were suitable for establishing secure communications between a low-power wireless device and a powerful base station. Unfortunately, Shim pointed out Wong and Chan’s schemes were incurred the unknown key-shared attack, then he proposed an improved scheme to o...

We propose a new digital signature scheme based on a non-commutative group where the conjugacy search problem is hard and the conjugacy decision problem is feasible. We implement our signature scheme in the braid groups and prove that an existential forgery of the implementation under no message attack gives a solution to a variation of conjugacy search problem. Then we discuss performance of o...

A Proxy signature scheme enables a proxy signer to sign a message on behalf of the original signer. In this paper, we propose ECDLP based solution for chen et. al [1] scheme. We describe efficient and secure Proxy multi signature scheme that satisfy all the proxy requirements and require only elliptic curve multiplication and elliptic curve addition which needs less computation overhead compare...

A secure scheme of restrictive partially blind signature was presented. The proposed scheme has several advantages over the previous scheme: 1. The scheme is provable secure against the one-more signature forgery under the adaptively parallel attack. 2. The issued signatures can be of polynomial number whereas the previous work allows only logarithmic number. 3. The scheme is more efficient tha...

In 2004, Yoon et al. proposed a user authentication scheme based on generalized ElGamal signature scheme using smart cards. In their scheme, the previous session keys will be compromised if the secret key of the system is leaked. In this paper, we propose a new scheme which can offer forward secrecy. Our scheme is also secure against forgery attack while keeping the merits of the scheme propose...