06/08/22 17:37:55
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ハッシュの強度はこれが参考になるかな?
[鏡] 「安全な鍵長の下限」とは -- 戯れ言++
URLﾘﾝｸ(www.baldanders.info)
でまとめられている NIST の報告を参考に、"Beyond 2030 (min. of 128 bits of
strength)"とするなら、下限が SHA-256 な感じですかね。
でも、SHA-512 使っても頭 160 bit しか使われないみたいですね?
> * 2048-bit key, 224-bit q, * 2048-bit key, 256-bit q
のくせに 160-bit しか使ってないのはなぜだろ?
ま、別に SHA-512 にしても困ることは無いんじゃないかなとか。
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> DSA signatures MUST use hashes that are equal in size to the number of bits of q, the group
> generated by the DSA key's generator value. If the output size of the chosen hash is larger than
> the number of bits of q, the hash result is truncated to fit by taking the number of leftmost
> bits equal to the number of bits of q. This (possibly truncated) hash function result is treated
> as a number and used directly in the DSA signature algorithm.
URLﾘﾝｸ(www.ietf.org)