Abstract: Recently, Au et al. [Au et al. 2007] pointed out a seemingly neglected security concern for certificateless public key encryption (CL-PKE) scheme, where a malicious key generation center...
Recoverable and Untraceable E-Cash (2008)
Joseph K. Liu, Patrick P. Tsang, Duncan S. Wong
Abstract. In an electronic cash (e-cash) system, Recoverability means once you have lost your e-cash, you still can get back the amount of e-cash that you have lost. Untraceability means no one can...
Efficient Verifiable Ring Encryption for Ad Hoc Groups (2008)
Joseph K. Liu, Patrick P. Tsang, Duncan S. Wong
Abstract. We propose an efficient Verifiable Ring Encryption (VRE) for ad hoc groups. VRE is a kind of verifiable encryption [16,1,4,2,8] in which it can be publicly verified that there exists at...
(Convertible) Undeniable Signatures without Random Oracles (2008)
Tsz Hon Yuen, Man Ho Au, Joseph K. Liu, Willy Susilo
Abstract. We propose a convertible undeniable signature scheme without random oracles. Our construction is based on Waters ’ and Kurosawa and Heng’s schemes that were proposed in Eurocrypt 2005....
(Convertible) Undeniable Signatures without Random Oracles (2008)
Tsz Hon Yuen, Man Ho Au, Joseph K. Liu, Willy Susilo
Abstract. We propose a convertible undeniable signature scheme without random oracles. Our construction is based on Waters ' and Kurosawa and Heng's schemes that were proposed in Eurocrypt...
Verifiable Encryption in Anonymous Ad Hoc Groups (2007)
Joseph K. Liu, Victor K. Wei, Duncan S. Wong
Abstract. In a verifiable encryption, an asymmetrically encrypted ciphertext can be publicly verified to be decypherable by a designated receiver without revealing the plaintext. In this paper, we...
Joseph K. Liu, Victor K. Wei, Duncan S. Wong
Abstract. In a veriable encryption, an asymmetrically encrypted ciphertext can be publicly veried to be decipherable by a designated receiver while maintaining the semantic security of the message...
Self-Generated-Certificate Public Key Cryptography and (2007)
Certificateless Signature Encryption, Joseph K. Liu, Man Ho Au, Willy Susilo
Certificateless Public Key Cryptography (CL-PKC) enjoys a number of features of Identity-Based Cryptography (IBC) while without having the problem of key escrow. However, it does su#er to an attack...
Universal custodian-hiding verifiable encryption for discrete logarithms (2006)
Joseph K. Liu, Patrick P. Tsang, Duncan S. Wong, Robertw. Zhu
Abstract. We introduce the notion of Universal Custodian-Hiding Verifiable Encryption (UCH-VE) and propose a scheme of this type for discrete logarithms. A UCH-VE scheme allows an encryptor to...
ID-Based Ring Signature Scheme secure in the Standard Model (2006)
Man Ho Au, Joseph K. Liu, Y. H. Yuen, Duncan S. Wong
The only known construction of ID-based ring signature schemes which maybe secure in the standard model is to attach certificates to non-ID-based ring signatures. This method leads to schemes that...
Malicious KGC Attack in Certificateless Cryptography (2006)
Man Ho Au, Jing Chen, Joseph K. Liu, Yi Mu, Duncan S. Wong, Guomin Yang
Identity-based cryptosystems have an inherent key escrow issue, that is, the Key Generation Center (KGC) always knows user secret key. Thus, if the KGC is malicious, it can always impersonate the...
Practical Hierarchical Identity Based Encryption and Signature schemes without Random Oracles (2006)
Man Ho Au, Joseph K. Liu, Tsz Hon Yuen, Duncan S. Wong
In this paper, we propose a Hierarchical Identity Based Encryption scheme that is proven secure under the strongest model of [5] directly, without relying on random oracles. The size of the...
Ring signatures without random oracles (2006)
Joseph K. Liu, Victor K. Wei, Tsz Hon Yuen
Abstract. Since the formalization of ring signature by Rivest, Shamir and Tauman in 2001, there are lots of variations appeared in the literature. Almost all of the variations rely on the random...
Abstract A More Efficient Instantiation of Witness-Indistinguishable Signature (2005)
A ring signature or a witness-indistinguishable signature is a setup-free group signature with no group manager. Defined by a set of public keys, a group is created spontaneously without any group...
Solutions to Key Exposure Problem in Ring Signature (2005)
In this paper, we suggest solutions to the key exposure problem in ring signature. In particular, we propose the first forward secure ring signature scheme and the first key-insulated ring signature...
Ring Signatures without Random Oracles (2005)
Joseph K. Liu, Victor K. Wei, Tsz Hon Yuen
Since the formalization of ring signature by Rivest, Shamir and Tauman in 2001, there are lots of variations appeared in the literature. Almost all of the variations rely on the random oracle model...
A Suite of ID-Based Threshold Ring Signature Schemes with Different Levels of Anonymity (2005)
Man Ho Au, Man Ho Au, Joseph K. Liu, Joseph K. Liu, Patrick P. Tsang, Patrick P. Tsang, ...
Since the introduction of Identity-based (ID-based) cryptography by Shamir in 1984, numerous ID-based signature schemes have been proposed. In 2001, Rivest et al. introduced ring signature that...
Linkable spontaneous anonymous group signature for ad hoc groups (extended abstract (2004)
Joseph K. Liu, Victor K. Wei, Duncan S. Wong
Abstract. We present a linkable spontaneously anonymous group (LSAG) signature scheme (alternatively known as linkable ring signature scheme) satisfying the following three properties. (1) Anonymity,...
Separable linkable threshold ring signatures (2004)
Patrick P. Tsang, Victor K. Wei, Tony K. Chan, Man Ho Au, Joseph K. Liu, Duncan S. Wong
Abstract. 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...
Separable Linkable Threshold Ring Signatures (2004)
Patrick P. Tsang, Victor K. Wei, Tony K. Chan, Man Ho Au, Joseph K. Liu, Duncan S. Wong
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...
Linkable and anonymous signature for ad hoc groups (2004)
Joseph K. Liu, Victor K. Wei, Duncan S. Wong
Abstract. We present a 1-out-of-n group signature scheme that satisfies three major properties. (1) Anonymity, or signer-indistinguishability. (2) Linkability: That two signatures by the same signer...