Abstract. Cryptographic hash functions are an important tool in cryptography for applications such as digital fingerprinting of messages, message authentication, and key derivation. During the last five years, several fast software hash functions have been proposed; most of them are based on the design principles of Ron Rivest’s MD4. One such proposal was RIPEMD, which was developed in the framework of the EU project RIPE (Race Integrity Primitives Evaluation). Because of recent progress in the cryptanalysis of these hash functions, we propose a new version of RIPEMD with a 160-bit result, as well as a plug-in substitute for RIPEMD with a 128-bit result. We also compare the software performance of several MD4-based algorithms, which is of independent interest. 1

Centera uses cryptographic hash functions as a means of addressing stored objects, thus creating a new class of data storage referred to as CAS (content addressed storage). Such hashing serves the useful function of providing a means of uniquely identifying data and providing a global handle to that data, referred to as the Content Address or CA. However, such a model begs the question: how certain can one be that a given CA is indeed unique? In this paper we describe fundamental concepts of cryptographic hash functions, such as collision resistance, preimage resistance, and second-preimage resistance. We then map these properties to the MD5 and SHA-256 hash algorithms, which are used to generate the Centera content address. Finally, we present a proof of the collision resistance of the Centera Content Address.

The recent collision attacks on the MD hash function family do not depend on the constants used in the function, but rather on its structure (i.e., changing the constants will not affect the differential analysis based attacks). Thus, is seems that the role of constants in maintaining security and preventing these attacks is unclear, at best, for this case and in particular fixing or varying the constants will not matter for these analyses. In this work we present a methodological investigation into the case of block-cipher based PGV hash functions family, and investigate the importance of constants in securing these designs. To this end we consider the twelve variants of the PGV family that yield secure hash in the generic ideal cipher case (as was shown by Black, Rogaway and Shrimpton), but consider them under concrete instantiation. To investigate the role of constant in the key derivation procedure we just ignore the constants. In this more uniform setting we further consider a very regular

. Cryptographic hash functions are an importanttoolincryptography for applications such as digital fingerprinting of messages, message authentication, and key derivation. During the last fiveyears, several fast software hash functions have been proposed# most of them are based on the design principles of Ron Rivest's MD4. One such proposal was RIPEMD, whichwas developed in the framework of the EU project RIPE (Race Integrity Primitives Evaluation). Because of recent progress in the cryptanalysis of these hash functions, we propose a new version of RIPEMD with a 160-bit result, as well as a plug-in substitute for RIPEMD with a 128-bit result. We also compare the software performance of several MD4-based algorithms, which is of independentinterest. 1 Introduction and Background Hash functions are functions that map bitstrings of arbitrary finite length into strings of fixed length. Given h and an input x, computing h(x)mustbeeasy. A one-way hash function must satisfy the following prop...

Abstract- In this paper, a new hash function based on RC4 stream cipher is proposed. The proposed RC4-based hash function has several advantages over many well-known hash functions. Its efficiency is much better than many widely used known hash function (e.g., MD5 and SHA-l). The application of the proposed hash function can be extended to the ultra-low devices for Ubiquitous computing, which most other hash functions do not apply. The structure of the proposed hash function is absolutely different from the broken hash function class (e.g., SHA family) so that people cannot use the existing attack strategies to break the proposed hash function. The proposed hash function is very simple and rules out all possible generic attacks. We proved that this hash function is secure and efficient.