Learn More
" Certificateless public-key cryptosystem " is a new and attractive paradigm, which avoids the inherent key escrow property in identity-based public-key cryptosystems, and does not need expensive certificates as in the public key infrastructure. A strong security model for certificateless public key encryption was established by Al-Riyami and Paterson in(More)
Identity-based cryptosystems have an inherent key escrow issue, that is, the Key Generation Center (KGC) always knows user secret key. If the KGC is malicious, it can always impersonate the user. Certificateless cryptography, introduced by Al-Riyami and Paterson in 2003, is intended to solve this problem. However, in all the previously proposed(More)
We present a linkable spontaneously anonymous group (LSAG) signature scheme (alternatively known as linkable ring signature scheme) satisfying the following three properties. (1) Anonymity, or signer indis-tinguishability. (2) Linkability: That two signatures by the same signer can be linked. (3) Spontaneity: No group secret, therefore no group manager or(More)
In this paper, we consider the problem of mutually authenticated key exchanges between a low-power client and a powerful server. We show how the Jakobsson-Pointcheval scheme proposed recently [15] can be compromised using a variant of interleaving attacks. We also propose a new scheme for achieving mutually authenticated key exchanges. The protocol is(More)
A ring signature scheme is a group signature scheme with no group manager to setup a group or revoke a signer. A linkable ring signature, introduced by Liu, et al. [20], additionally allows anyone to determine if two ring signatures are signed by the same group member (a.k.a. they are linked). In this paper, we present the first separable link-able ring(More)
Optimistic fair exchange is a kind of protocols to solve the problem of fair exchange between two parties. Almost all the previous work on this topic are provably secure only in the random oracle model. In PKC 2007, Dodis et al. considered optimistic fair exchange in a multiuser setting, and showed that the security of an optimistic fair exchange in a(More)