Symmetric Key Protocol Research Articles

Permutation parity machines for neural synchronization

Synchronization of neural networks has been studied in recent years as an alternative to cryptographic applications such as the realization of symmetric key exchange protocols. This paper presents a first view of the so-called permutation parity machine, an artificial neural network proposed as a binary variant of the tree parity machine. The dynamics of the synchronization process by mutual learning between permutation parity machines is analytically studied and the results are compared with those of tree parity machines. It will turn out that for neural synchronization, permutation parity machines form a viable alternative to tree parity machines.

Static validation of security protocols

We methodically expand protocol narrations into terms of a process algebra in order to specify some of the checks that need to be made in protocol. We then apply static analysis technology to develop an automatic validation procedure for protocols. Finally, we demonstrate that these techniques suffice to identify several authentication flaws in symmetric and asymmetric key protocols such as Needham-Schroeder symmetric key, Otway-Rees, Yahalom, Andrew Secure RPC, Needham-Schroeder asymmetric key. and Beller-Chang-Yacobi MSR.

Formalizing and Analyzing the Needham-Schroeder Symmetric-Key Protocol by Rewriting

This paper reports on work in progress on using rewriting techniques for the specification and the verification of communication protocols. As in Genet and Klay's approach to formalizing protocols, a rewrite system R describes the steps of the protocol and an intruder's ability of decomposing and decrypting messages, and a tree automaton A encodes the initial set of communication requests and an intruder's initial knowledge. In a previous work we have defined a rewriting strategy that, given a term t that represents a property of the protocol to be proved, suitably expands and reduces t using the rules in R and the transitions in A to derive whether or not t is recognized by an intruder. In this paper we present a formalization of the Needham-Schroeder symmetric-key protocol and use the rewriting strategy for deriving two well-known authentication attacks.

Analysing the Vulnerability of Protocols to Produce Known-pair and Chosen-text Attacks

In this paper we report on an analysis for finding known-pair and chosen-text attacks in protocols. As these attacks are at the level of blocks, we extend the attacker by special capabilities related to block chaining techniques. The analysis is automated using Blanchet's protocol verifier and illustrated on two well-known protocols, the Needham-Schroeder-Lowe public-key protocol as well as the Needham-Schroeder symmetric-key protocol. On the first protocol, we show how the special intruder capabilities related to chaining may compromise the secrecy of nonces and that chosen- ciphertext attacks are possible. We propose two modified versions of the protocol which strengthen its security. We then illustrate known-pair and chosen-plaintext attacks on the second protocol.