Identity Based Self Delegated Signature - Self Proxy Signatures

A proxy signature scheme is a variant of digital signature scheme in which a signer delegates his signing rights to another person called proxy signer, so that the proxy signer can generate the signature of the actual signer in his absence. Self Proxy Signature (SPS) is a type of proxy signature wherein, the original signer delegates the signing rights to himself (Self Delegation), there by generating temporary public and private key pairs for himself. Thus, in SPS the user can prevent the exposure of his private key from repeated use. In this paper, we propose the first identity based self proxy signature scheme. We give a generic scheme and a concrete instantiation in the identity based setting. We have defined the appropriate security model for the same and proved both the generic and identity based schemes in the defined security model

An Efficient Secure Anonymous Proxy Signature Scheme

Proxy signature schemes can be used in many business applications such as when the original signer is not present to sign important documents. Any proxy signature scheme has to meet the identifiability, undeniability, verifiability and unforgeability security requirements. In some conditions, it may be necessary to protect the proxy signer’s privacy from outsiders or third parties. Recently, several studies about proxy signature schemes have been conducted but only Yu et al.’ anonymous proxy signature scheme proposed in 2009 attempting to protect the proxy signer’s privacy from outsiders. They claimed their scheme can make the proxy signer anonymous. However, based on our research, we determined that this was not the case and the proxy signer’s privacy was not anonymous. Hence, in this paper, we propose a new anonymous proxy signature scheme that truly makes the proxy signer anonymous while making it more secure and efficient when compared with Yu et al.’s scheme in 2009. Our proxy signature scheme consists of two constructions. First, we mainly use random numbers and bilinear pairings to attain the anonymous property in our proxy. Secondly, we increase the security, integrity, and efficiency of our proxy through modifications

A Thesis: A CRYPTOGRAPHIC STUDY OF SOME DIGITAL SIGNATURE SCHEMES.

In this thesis, we propose some directed signature schemes. In addition, we have discussed their applications in different situations. In this thesis, we would like to discuss the security aspects during the design process of the proposed directed digital signature schemes. The security of the most digital signature schemes widely use in practice is based on the two difficult problems, viz; the problem of factoring integers (The RSA scheme) and the problem of finding discrete logarithms over finite fields (The ElGamal scheme). The proposed works in this thesis is divided into seven chapters