Braids groups provide an alternative to number theoretic public cryptography and can be implemented quite efficiently. The paper proposes five signature schemes: Proxy Signature, Designated Verifier, Bi-Designated Verifier, Designated Verifier Proxy Signature And Bi-Designated Verifier Proxy Signature scheme based on braid groups. We also discuss the security aspects of each of the proposed sch...

A new type of signature is presented in this paper, named adaptable group-oriented signature. In contrast with traditional group-oriented signature, the new one laid a strong emphasis on how to improve the signer’s efficiency. In fact, this new type of group-oriented signature can be seen as a type of designated verifier signature. In contrast with the ordinary designated verifier signature, it...

The designated verifier signature only enables the designated verifier to check the correctness of the signature, while any third party can not verify whether this signature is valid or not. Most of the previous designated verifier signature schemes depend on certificate-based cryptography or identity-based cryptography, while little attention has been paid to the certificateless designated ver...

A digital signature provides the authenticity of a signed message with respect to a public key and a certificate provides the authorization of a signer for a public key. Digital signature and certificate are generated independently by different parties, but they are verified by the same verifier who wants to verify the signature. In the point of a verifier, verifying two independent digital sig...

In Undeniable Signature, a signature’s validity can only be confirmed or disavowed with thehelp of an alleged signer via a confirmation or disavowal protocol. A Convertible undeniablesignature further allows the signer to release some additional information which can make anundeniable signature become publicly verifiable. In this work we introduce a new kind of attacks,called cl...

Abstract Multi-authenticated encryption is an important message transmission technique, which can send message in a secure and authentic way, and allows a group of signers to cooperatively produce a valid authenticated ciphertext so that only the specific recipient can recover the message and verify the signature. In 2008, Wu et al. proposed a convertible multi-authenticated encryption scheme. ...

We introduce a new concept called convertible undeniable signature schemes. In these schemes, release of a single bit string by the signer turns all of his signatures, which were originally undeniable signatures, into ordinary digital signatures. We prove that the existence of such schemes is implied by the existence of digital signature schemes. Then, looking at the problem more practically, w...

The notion of strong designated verifier signature was put forth by Jakobsson, Sako and Impagliazzo in 1996, but the formal definition was defined recently by Saeednia, Kremer and Markowitch in 2003 and revisited by Laguillaumie and Vergnaud in 2004. In this paper, we firstly propose the notion of short strong designated verifier signature scheme, and extend it to the short identity-based stron...

Proving knowledge of a signature has many interesting applications. As one of them, the Universal Designated Verifier Signature (UDVS), introduced by Steinfeld et al. in Asiacrypt 2003 aims to protect a signature holder’s privacy by allowing him to convince a verifier that he holds a valid signature from the signer without revealing the signature itself. The essence of the UDVS is a transformat...

In 2009, Lin et al. proposed a digital multi-signature scheme based on the concepts of generalized conic curves over Zn. They claimed that the multi-signature scheme is well secured and the forgery attack is infeasible on it. Unfortunately, three weaknesses on their proposed multi-signature have been observed and it has been shown that an attacker can compute the secret pairs of all signers usi...