Abstract: An appraisal is given of the current status, both technical and nontechnical, of cryptologic research The principal concepts of both secret-key and public-key cryptography are described CE Shanon's theory of secrecy (1949) and GJ Simon's theory authenticity (1984) are reviewed for the insight that they give into practical cryptographic systems Public-key concepts are illustrated through consideration of the Diffie-Hellman public-key-distribution system and the Rivest-Shamir-Adleman public-key cryptosystem The subtleties of cryptographic protocols are shown through consideration of some such specific protocols >

Abstract: The present invention relates to cryptographic systems, and particularly, public key cryptographic systems implemented in digital communication devices.

Abstract: A set of clawfree functions is a set of functions that are all easily computable, but for which it is hard to simultaneously find preimages of an element under different functions. In this thesis we develop a formalism for describing such functions, and show several techniques for building them, some new and others well known. We show how clawfree functions can be extremely useful, in the construction of for example collision free hash functions and of cryptographic protocols in general. In particular, we show how to solve the famous multiparty computation problem, while achieving un conditional privacy protection for one participant. This is the optimal result in the model of communication we consider.

Abstract: This paper describes results and experiences gained from the test implementation of an interactive identification scheme. It was intended to exploit the feasibility of an asymmetric crypto protocol for a state-of-the-art smart card environment. For that reason the identification scheme proposed by Fiat and Shamir was implemented between an actual smart card microprocessor and an industry standard personal computer with a smart card interface. The limits of a current smart card processor in terms of volatile and nonvolatile memory capacity and instruction set turned out to be a rather strict limitation for the choice of the algorithms used. The most time consuming task during the protocol is modular multiplication. Due to the processor structure it is performed as separate multiplication and reduction, where reduction is led back to integer multiplication. The current implementation allows the authentication of a 120 byte identification string at a security level of 2-20 within an average time of about 6 seconds. The experiences gained during this implementation led to a set of requirements for a future specialised processor for asymmetric cryptographic protocols that will be needed to increase this performance by some orders of magnitude.

Abstract: We present a simple protocol for secure circuit evaluation. In its most basic formulation, the protocol enables two players C and D to cooperate in the computation of f(x) while D conceals her data x from C and C conceals his circuit for f from D.

Abstract: A authentication protocol with security imbedded into it is reported. It is based on a combination of the private-key and the public-key encryption systems. A Petri-net model of the protocol is presented to verify that the protocol is correct and deadlock-free. >

Abstract: An embedded network security prototype is being developed to research issues associated with embedding cryptography into a trusted computer system. Trusted Information Systems (TIS) is implementing SP4, mail, and key management secure data network systems (SDNS) protocols in the Trusted Mach operating system using unclassified cryptography. The TIS prototype uses transport control protocol/internet protocol (TCP/IP) rather than OSI (Open Systems Interconnection) communications protocols. The authors discuss the organization and interactions of the embedded cryptorelated functions implemented in the prototype. >