Showing papers by "Chris J. Mitchell published in 1998"
TL;DR: Certain key establishment protocols specified in an international standard and a draft international standard are considered and it is shown that this claim is suspect for most of the protocols concerned.
Abstract: Certain key establishment protocols specified in an international standard and a draft international standard are considered. These protocols are all intended to provide joint key control, i.e. the protocols are designed to prevent either party choosing the key value. It is shown that this claim is suspect for most of the protocols concerned.
113 citations
TL;DR: A secure billing scheme for value-added information services using micropayments is presented and will be validated in a trial to be conducted over an experimental UMTS platform.
Abstract: This paper presents solutions developed in the ACTS ASPeCT project for advanced security features in UMTS. In particular, a secure billing scheme for value-added information services using micropayments is presented. The solutions will be validated in a trial to be conducted over an experimental UMTS platform.
34 citations
TL;DR: A simple modification to the protocol is proposed which avoids a recently described attack on a key establishment protocol contained in a draft international standard.
Abstract: We consider a recently described attack on a key establishment protocol contained in a draft international standard. Based on an observation as to why the attack is possible, we propose a simple modification to the protocol which avoids the attack.
27 citations
TL;DR: In this correspondence it is shown that the set of infinite sequences of finite depth corresponds to a set of equivalence classes of rational polynomials, and the depth distributions for all linear cyclic codes are given.
Abstract: The notion of the depth of a binary sequence was introduced by Etzion. In this correspondence we show that the set of infinite sequences of finite depth corresponds to a set of equivalence classes of rational polynomials. We go on to characterize infinite sequences of finite depth in terms of their periodicity. We conclude by giving the depth distributions for all linear cyclic codes.
19 citations
Journal Article•
TL;DR: The first part of this paper is devoted to explaining what key escrow is and why it exists, and attempts to put it into a historical context as discussed by the authors. But the subsequent focus is primarily on key-escrow schemes which will work in an international environment.
Abstract: The first part of this paper is devoted to explaining what key escrow is and why it exists, and attempts to put it into a historical context. The subsequent focus is primarily on key escrow schemes which will work in an international environment. The possibility of using conventional key distribution techniques to provide key escrow services in an international context is first considered, and the associated problems are explored. The 'Royal Holloway' (RH) key escrow scheme is then described in a way which is intended to clarify and motivate its design, and the properties of this scheme and some related schemes are considered.
6 citations
TL;DR: It is shown that Shao's scheme is vulnerable to homomorphism attacks, and although the Elgamal scheme and its variants (e.g. DSS) are subject to homology attacks, the success of such an attack appears to be no more likely than finding a discrete logarithm, as long as the random integer used to construct the signature is chosen at random.
Abstract: Contrary to Shao's claim for developing a signature scheme based on a discrete logarithm without using a one-way hash function (see ibid., vol.34, no.11, pp.1079-80, 1998), we have shown that Shao's scheme is vulnerable to homomorphism attacks. The main justification for the use of Shao's scheme is its resistance to homomorphism and substitution attacks. Substitution attacks can be avoided by the use of a one-way hash-function, and so there appears to be no reason to use Shao's scheme. Although the Elgamal scheme and its variants (e.g. DSS) are subject to homomorphism attacks, the success of such an attack appears to be no more likely than finding a discrete logarithm, as long as the random integer used to construct the signature is chosen at random.
6 citations
01 Jan 1998
TL;DR: A protocol developed by the ASPeCT project for secure billing that provides the incontestable charging that is required for UMTS is presented.
Abstract: We present a protocol developed by the ASPeCT project for secure billing that provides the incontestable charging that is required for UMTS. This protocol realises a payment system for value added services. We describe the protocol and in particular the design features that are of particular relevance to the UMTS environment. We also describe the configuration of a field trial of this protocol over the experimental UMTS platform developed by the project EXODUS.
2 citations
TL;DR: A block cipher based hash function of Yi and Lam is analysed and shown to be significantly weaker than originally intended.
Abstract: A block cipher based hash function of Yi and Lam is analysed and shown to be significantly weaker than originally intended.
2 citations
TL;DR: New construction methods for Perfect Factors are introduced based on the theory of cyclic codes, interleaving techniques and the Lempel homomorphism, which enable the existence question for Perfect factors for window sizes at most six to be settled.
Abstract: In this paper, we introduce new construction methods for Perfect Factors. These are based on the theory of cyclic codes, interleaving techniques and the Lempel homomorphism. The constructions enable us to settle the existence question for Perfect Factors for window sizes at most six.
2 citations