International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Richard Comley

Publications

Year
Venue
Title
2005
EPRINT
Efficient Certificateless Public Key Encryption
Zhaohui Cheng Richard Comley
In [3] Al-Riyami and Paterson introduced the notion of "Certificateless Public Key Cryptography" and presented an instantiation. In this paper, we revisit the formulation of certificateless public key encryption and construct a more efficient scheme and then extend it to an authenticated encryption.
2005
EPRINT
On The Indistinguishability-Based Security Model of Key Agreement Protocols-Simple Cases
Since Bellare and Rogway's work [15], the indistinguishability-based security models of authenticated key agreement protocols in simple cases have been evolving for ten years. In this report, we review and organize the models under a unified framework with some new extensions. By providing a new ability (the Coin query) to adversaries and redefining two key security notions, the framework fully exploits an adversary's capability and can be used to prove all the commonly required security attributes of key agreement protocols with key confirmation. At the same time, the Coin query is also used to define a model which can be used to heuristically evaluate the security of a large category of authenticated protocols without key confirmation. We use the models to analyze a few pairing-based authenticated key agreement protocols.
2005
EPRINT
Identity-Based Key Agreement with Unilateral Identity Privacy Using Pairings
In most of the existing identity-based key agreement schemes, it is usually assumed that either the communicated parties know each other's identifier before the protocol starts or their identifiers are transferred along with the protocol messages. However, these schemes are not suitable for use in many real-world applications aimed to achieve unilateral identity privacy, which means that one communicating party does not want to expose his identifier to an outsider while his partner cannot know his identifier in advance. In this paper, we propose an efficient identity-based two-party key agreement scheme with unilateral identity privacy using pairing, and formally analyze its security in a modified Bellare-Rogaway key agreement security model.
2004
EPRINT
Pairing-Based One-Round Tripartite Key Agreement Protocols
Zhaohui Cheng Luminita Vasiu Richard Comley
Since Joux published the first pairing-based one-round tripartite key agreement protocol [13], many authenticated protocols have been proposed. However most of them were soon broken or demonstrated not to achieve some desirable security attributes. In this paper we present a protocol variant based on Shim's work [20]. As the formalized model of this type of AK protocols is not mature, the security properties of the protocol are heuristically investigated by attempting a list of attacks. The attack list presented in the paper has both the importance in theory and the meaning in practice and can be used to evaluate other tripartite and group key agreement protocols.
2004
EPRINT
Attacks On An ISO/IEC 11770-2 Key Establishment Protocol
Zhaohui Cheng Richard Comley
Two possible types of attack (a replay attack and a type attack) on a key establishment protocol (mechanism 12) standardised in ISO/IEC 11770-2 are described and two solutions are proposed.