Cryptanalysis of a Hash Function Based on Quasi-cyclic Codes

Cryptanalysis of a Hash Function Based on Quasi-cyclic Codes

At the ECRYPT Hash Workshop 2007, Finiasz, Gaborit, and Sendrier proposed an improved version of a previous provably secure syndrome-based hash function. The main innovation of the new design is the use of a quasi-cyclic code in order to have a shorter description and to lower the memory usage. In this paper, we look at the security implications of using a quasi-cyclic code. We show that this v...

On the Grobner Basis of a Family of Quasi-Cyclic LDPC Codes

Cryptanalysis of Two McEliece Cryptosystems Based on Quasi-Cyclic Codes

We cryptanalyse here two variants of the McEliece cryptosystem based on quasi-cyclic codes. Both aim at reducing the key size by restricting the public and secret generator matrices to be in quasi-cyclic form. The first variant considers subcodes of a primitive BCH code. The aforementioned constraint on the public and secret keys implies to choose very structured permutations. We prove that thi...

An Improved Hash Function Based on the Tillich-Zémor Hash Function

Using the idea behind the Tillich-Zémor hash function, we propose a new hash function. Our hash function is parallelizable and its collision resistance is implied by a hardness assumption on a mathematical problem. Also, it is secure against the known attacks. It is the most secure variant of the Tillich-Zémor hash function until now.

Designing and improving code-based cryptosystems

In modern cryptography, the security of the most secure cryptographic primitives is based on hard problems coming from number theory such as the factorization and the discrete logarithm problem. However, being mainly based on the intractability of those problems seems to be risky. In 1994, Peter Shor showed how these two problems can be solved in polynomial time using a quantum computer. In con...