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...

To enhance the efficiency of threshold group signature schemes, Yu and Chen, recently, proposed an efficient threshold group signature scheme. By using elliptic curves, the proposed scheme can use short secret key and reduces the load of signature verification. However, in this paper we find that there are many ambiguities in the proposed scheme. The verifiers cannot verify valid signatures, wh...

The fair blind signature scheme indeed plays significant roles in a wide variety of e-commerce and network applications; for example, it can withstand the misapplication of financial crime in electronic cash payment systems. In this paper, we propose a new fair blind signature scheme with message recovery using the self-certified pairing-based public key cryptosystem. Preserving the merits inhe...

We present a blind signature scheme that is efficient and provably secure without random oracles under concurrent attacks utilizing only four moves of short communication. The scheme is based on elliptic curve groups for which a bilinear map exists and on extractable and equivocable commitments. The unforgeability of the employed signature scheme is guaranteed by the LRSW assumption while the b...

This manuscript presents a fast blind signature scheme with extremely low computation for users. Only several modular additions and multiplications are required for a user to obtain and verify a signature in the proposed scheme. Comparing with the existing ones in the literature, the scheme greatly reduces the computations for users. Keywords—Blind signatures, Untraceable electronic cash, Secur...

-------------------------------------------------------------------ABSTRACT-----------------------------------------------------Blind signature scheme provide the feature that a user is able to get a signature without giving the actual message to the signer. Many Blind signature schemes have been proposed in which security are based on intractability of factoring or DLP (Discrete Logarithm Prob...

Recently the bilinear pairing such as Weil pairing or Tate pairing on elliptic curves and hyperelliptic curves have been found various applications in cryptography. Several identity-based (simply ID-based) cryptosystems using bilinear pairings of elliptic curves or hyperelliptic curves were presented. Blind signature and ring signature are very useful to provide the user’s anonymity and the sig...

In this paper, we propose a new ID-based blind signature scheme based on bilinear pairings from scratch (i.e. without using existing ID-based signature schemes, and without using existing computational assumptions). First, the round complexity of our ID-based blind signature scheme is optimal. Namely, each interactive signature generation requires the requesting user and the signer to transmit ...

In this paper, we reinvestigate the security analysis of blind signature scheme over braid groups proposed by Verma in 2008. A blind signature scheme is a cryptographic primitive used for e-commerce for getting a signature from the signer without revealing any information about its contents. These schemes are especially used in e-transactions, e-votings, DRM systems, etc. The security of blind ...

Blind signatures enable users to obtain valid signatures for a message without revealing its content to the signer. This paper presents a new blind signature scheme, i.e. identity-based blind signature scheme with message recovery. Due to the message recovery property, the new scheme requires less bandwidth than the identitybased blind signatures with similar constructions. The scheme is based ...