Hash Functions and Information Theoretic Security

Nasour BAGHERI  Lars R. KNUDSEN  Majid NADERI  Sφren S. THOMSEN  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E92-A   No.12   pp.3401-3403
Publication Date: 2009/12/01
Online ISSN: 1745-1337
Print ISSN: 0916-8508
Type of Manuscript: LETTER
Category: Cryptography and Information Security
Keyword: 
hash functions,  information theoretic security,  query complexity,  permutation-based hash functions,  

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Summary: 
Information theoretic security is an important security notion in cryptography as it provides a true lower bound for attack complexities. However, in practice attacks often have a higher cost than the information theoretic bound. In this paper we study the relationship between information theoretic attack costs and real costs. We show that in the information theoretic model, many well-known and commonly used hash functions such as MD5 and SHA-256 fail to be preimage resistant.