This paper introduces a new concept called controllable ring signature which is ring signature with additional properties as follow. (1) Anonymous identifica-tion: by an anonymous identification protocol, the real signer can anonymously prove his authorship of the ring signature to the verifier. And this proof is non-transferable. (2) Linkable signature: the real signer can generate an anonymou...

Recently, Boyen at PKC 2010 proposed a lattice-based signature scheme in the standard model. In this paper, we show that his signature scheme does not satisfy strong unforgeability. In other words, an adversary can produce a new signature for a message M after seeing a signature of the message M. Then we present an improved scheme and prove that the improved scheme satisfies strong unforgeabili...

In this paper, we propose a new notion called Revocable-iffLinked Ring Signature (R-iff-L Ring Signature). In R-iff-L ring signatures, a signer can sign on behalf of the whole group, just like ordinary ring signatures. However, if he signs twice or more, he can be linked and his identity can be revoked by everyone. We formally define a new security model for the new notion in identity-based (ID...

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...

Handwritten signature is being used in various applications on daily basis. The problem arises when someone decides to imitate our signature and steal our identity. Therefore, there is a need for adequate protection of signatures and a need for systems that can, with a great degree of certainty, identify who is the signatory. This paper presents previous work in the field of signature and write...

Digital signatures provide authentication and non-repudiation in a public way in the sense that anyone can verify the validity of a digital signature using the corresponding public key. In this paper, we consider the issues of (1) signature privacy and (2) the corresponding public provability of signature. We propose a new digital signature variant, secret signature, which provides authenticati...

We propose a secure threshold signature scheme without trusted dealer. Our construction is based on the recently proposed signature scheme of Waters in EUROCRYPT’05. The new threshold signature scheme is more efficient than the previous threshold signature schemes without random oracles. Meanwhile, the signature share generation and verification algorithms are non-interactive. Furthermore, it i...

This paper presents an efficient algorithm for the classification of features into strong and weak features for every distinct subject to create an intelligent online signature verification system. Whereas Euclidean distance classifier is used for validation processes and low error rates obtained illustrate the feasibility of the algorithm for an online signature verification system. Keywords-S...