Kind Of Signature Scheme Research Articles

Efficient and secure pairing-free certificateless directed signature scheme

In an ordinary signature scheme any one can verify the validity of a signature produced by the signer. But public verifiability of signatures is not desirable in some applications where the signed message is sensitive to the signature receiver, for example signatures on medical records, tax information. To meet this requirement, the concept of directed signature was introduced. A directed signature scheme is a kind of signature scheme in which the verification ability is controlled by the signer. Many directed signature schemes have been proposed in different cryptographic settings and most of the schemes are using bilinear pairings over elliptic curves. But the computation of a bilinear pairing is very expensive. Hence the schemes which use pairings are less efficient and are not much applicable in practice. In order to improve the computational and communicational efficiency, in this paper, we propose a pairing- free certificateless directed signature scheme. The proposed scheme is proven secure in the random oracle model under the assumption that the elliptic curve discrete logarithm problem is hard. We compare our scheme with well known existing schemes and efficiency analysis shows that the proposed scheme is more efficient.

Research on anonymous signatures and group signatures

In this paper, we analyze the conventional group signature schemes, and propose the notion of conflict of authenticated contents which implies the unconquerable drawbacks of the current group signature schemes and threshold signature schemes. We discuss an important problem of group signature, that is, whether the group signature is produced on behalf of the group or on behalf of its members, and consider that the group signatures should be produced on behalf of the group. A new kind of signature scheme, which is called anonymous signatures, has been proposed. And we indicate that the previously proposed group signature is actually a kind of anonymous signatures. In order to realize the anonymous signatures, we design two kinds of implementation schemes, whose performances are analyzed and compared. Finally, we introduce the new notion of real group signatures, describe its characteristics, present one realization based on pivot threshold scheme which we designed to solve the conflict of authenticated contents problem.

Proxy signature schemes with time limitation

In this paper, we propose a key-revolution concept for proxy signature schemes to obtain a property of time limitation on delegation duration of proxy signatures. Proxy signature scheme is a kind of signature schemes in which an original signer delegates its signing capability to a designated signer called a proxy signer. Then, the proxy signer creates a digital signature on behalf of the original signer. The problems of time limitation on delegation duration are essential for proxy signature schemes. We propose a proxy signature scheme with time limitation in which a proxy key is renewed in each period until the end of period. Then, the proxy key is revoked automatically.