A Strict Evaluation on the Number of Conditions for SHA-1 Collision Search

Jun YAJIMA; Terutoshi IWASAKI; Yusuke NAITO; Yu SASAKI; Takeshi SHIMOYAMA; Thomas PEYRIN; Noboru KUNIHIRO; Kazuo OHTA

doi:10.1587/transfun.E92.A.87

Special Section on Cryptography and Information Security

A Strict Evaluation on the Number of Conditions for SHA-1 Collision Search

Jun YAJIMA, Terutoshi IWASAKI, Yusuke NAITO, Yu SASAKI, Takeshi SHIMOYAMA, Thomas PEYRIN, Noboru KUNIHIRO, Kazuo OHTA

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Keywords: hash function, collision search, SHA-1, disturbance vector

JOURNAL RESTRICTED ACCESS

2009 Volume E92.A Issue 1 Pages 87-95

DOI https://doi.org/10.1587/transfun.E92.A.87

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Abstract

This paper proposes a new algorithm for evaluating the number of chaining variable conditions (CVCs) in the selecting step of a disturbance vector (DV) for the analysis of SHA-1 collision search. The algorithm is constructed by combining four strategies, that can evaluate the number of CVCs more strictly compared with the previous approach. By using our method, we found some DVs that have 57 (or 59) essential CVCs for 1st (or 2nd) block in the case if we assume that we can modify messages up to step 25, which we have not confirmed the practicability of the assumption.

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