In 1995, Ajtai described a construction of one-way functions whose security is equivalent to the difficulty of some well known approximation problems in lattices. We show that essentially the same construction can also be used to obtain collision-free hashing. This paper contains a self-contained proof sketch of Ajtai’s result.

BLAKE is a hash function selected by NIST as one of the 14 second round candidates for the SHA-3 Competition. In this paper, we follow a bottom-up approach to exhibit properties of BLAKE and of its building blocks: based on differential properties of the internal function G, we show that a round of BLAKE is a permutation on the message space, and present an efficient inversion algorithm. For 1....

The security of iterated hash functions relies on the properties of underlying compression functions. We study highly efficient compression functions based on block ciphers. We propose a model for highrate compression functions, and give an upper bound for the rate of any collision resistant compression function in our model. In addition, we show that natural generalizations of constructions by...

BLAKE2 is a hash function introduced at ACNS 2013, which has been adopted in many constructions and applications. It is a successor to the SHA-3 finalist BLAKE, which received a significant amount of security analysis. Nevertheless, BLAKE2 introduces sufficient changes so that not all results from BLAKE carry over, meaning new analysis is necessary. To date, all known cryptanalysis done on BLAK...

The hash function JH [20] is one of the five finalists of the NIST SHA-3 hash competition. It has been recently tweaked for the final by increasing its number of rounds from 35.5 to 42. The previously best known results on JH were semi-free-start near-collisions up to 22 rounds using multi-inbound rebound attacks. In this paper we provide a new differential path on 32 rounds. Using this path, w...

Recently, Hwang and Shi proposed an efficient proxy signature scheme without using one-way hash functions. In their scheme, an original signer needn’t send a proxy certificate to a proxy signer through secure channels. However, there are two public key substitution methods can be used to attack their scheme. In this article, we show that their scheme is vulnerable to the public key substitution...

In this paper we describe the construction of Turbo SHA-2 family of cryptographic hash functions. They are built with design components from the SHA-2 family, but the new hash function has three times more chaining variables, it is more robust and resistant against generic multi-block collision attacks, its design is resistant against generic length extension attacks and it is 2 8 times faster ...

Invertibility attack is a hostile measure to breach watermarking systems. In this paper, a novel watermarking protocol using a one-way hash function and a check of random watermarks is proposed in order to combat invertibility attacks. The described technique can be used in conjunction with any watermarking algorithm, no matter it is kept secret or made public, without resorting to a third part...

This paper characterizes collision preserving padding rules and provides variants of Merkle-Damg̊ard (MD) which are having less or no overhead costs due to length. We first show that suffix-free property of padding rule is necessary as well as sufficient to preserve the collision security of MD hash function for an arbitrary domain {0, 1}∗. Knowing this, we propose a simple suffix-free padding r...

This paper presents an interesting application of the Tillich-Zémor function TZ . In particular, we emphasize the concatenation property of this one-way hash function, i.e. TZ(S j T ) = TZ(S)TZ(T ) where S and T are two binary strings. This property is combined with a multisignature scheme in a journalism context. The aim is to authenticate reports or interviews.