Security of hash functions SHA-1 and RIPEMD-160

September 8, 2004
CRYPTREC Cryptographic Technique Monitoring Subcommittee

The discovery of collision of hash functions SHA-0, RIPEMD, MD4, MD5, and HAVAL-128 was reported in an academic conference (CRYPTO 2004), and it was reported by some news medias as a big topic. The hash functions SHA-1 and RIPEMD-160 are listed in the e-Government Recommended Ciphers List , but their structure is different from the structure of hash functions with which collision was discovered this time, and it is considered that there is a big technical gap in discovering the collision by applying the analytical techniques so far made public. Therefore, we consider that there is no special change in the security of hash functions enumerated in the e-Government Recommended Ciphers List , despite the report made in an academic conference as mentioned above.

As shown in the Note of the e-Government Recommended Ciphers List, CRYPTREC recommends hash functions with a hash value of 256 bits or more,and considers it desirable to maintain and reinforce this policy.

At any rate, since there is no way to predict the development of research in the future, we will carefully continue monitoring activities in the future, too.

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CRYPTREC Secretariat
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