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Comment by kkl | Hacker News Reader

To make sure I understand correctly:

Suppose I had the magical ability to find a special value that would equal the IV listed in the link (i.e. 506b0178ff6d1890....) when that special value was applied to SHA-1. I could then use the results from this research to compute a collision using input that is prefixed with that special value?

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Yes. If you are able to construct P1 such that SHA1(P1) = IV1 and P2 s.t. SHA1(P2) = IV2, then

    SHA1(P1 + padding(P1) + M1) = SHA1(P2 + padding(P2) + M2) = f020486f071bf11053547a86f4a7153b3c950f4b

where padding(M) is the padding appended to message M as the first step of computing SHA1.

(edit: clarified padding)

Thanks for clarifying. That is a really concise explanation.

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