Dieter Gollmann

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Abstract: A fair non-repudiation protocol should not give the sender of a message an advantage over the receiver, or vice versa. We present a fair non-repudiation protocol that requires a trusted third party but attempts to minimize its involvement in the execution of the protocol. We draw particular attention to the nonstandard use of encryption in our(More)
Fairness may be a desirable property of a nonrepudiation service. Protocols can achieve fairness through the involvement of a trusted third party but the extent of the trusted third party's involvement can vary between protocols. Hence, one of the goals of designing an efficient non-repudiation protocol is to reduce the work load of the trusted third party.(More)
Ideally, a measure of the security of a system should capture quantitatively the intuitive notion of ‘the ability of the system to resist attack’. That is, it should be operational, reflecting the degree to which the system can be expected to remain free of security breaches under particular conditions of operation (including attack). Instead, current(More)
Abstract: The design of authentication protocols has proven to be surprisingly error-prone. We suggest that this is partly due to a language problem. The objectives of entity authentication are usually given in terms of human encounters while we actually implement message passing protocols. We propose various translations of the high-level objectives into a(More)
I . INTRODUCTION ESEARCH on public key algorithms has been conR cerned mainly with security aspects. The results of this research have induced sufficient confidence to apply public key cryptography on a larger scale. The I S 0 and CCITT have been discussing public key systems. As an example, take the CCITT directory authentication framework [12], which(More)
This article summarizes the objectives and structure of a seminar with the same title, held from July 20th to July 25th, 2008, at Schloss Dagstuhl, Germany. The seminar brought together researchers and policy-makers from all involved communities, to clarify what it is that identifies an insider threat, and to develop a common vision of how an insider can be(More)
Key-stream generators are discussed in which shift registers are clocked in a quasi-random manner under the control of other shift registers. They are a promising practical alternative to those using nonlinear combining functions on the outputs from regularly stepped shift registers and are now almost as well understood. Some World War I1 ciphers using(More)
This paper discusses non-repudiation services regarding the transfer of a message and classiies the roles of trusted third parties involved in non-repudiation services. We examine the selective receipt problem and the generation of time evidence, analyse the current state of the ISO/IEC 13888 drafts on non-repudiation mechanisms, and present a fair(More)