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Reversing an integer hash function

by flebron on 1/14/22, 6:06 PM with 16 comments

• by rurban on 1/14/22, 7:54 PM

  I'm collecting such inverters at https://github.com/rurban/smhasher/tree/inverse/inverse

  But only 3 so far.

• by superjan on 1/15/22, 2:08 PM

  Is there a category of hash functions that hash a 64/32 bit input to exactly 64/32 bits output, such that all inputs are uniquely preserved? This could be an interesting property for a hash table of integers, because a hash match implies a key match.

• by blastonico on 1/15/22, 9:15 PM

  > otherwise you could simply trace backwards and generate an input that produces a specific hash

  This is when I know for sure that I'm not included in that "you".

• by clon on 1/15/22, 1:36 PM

  Excellent tutorial for bitwise arithmetic this is. The key is the motivation you receive from the prospect of being able to do something that seems "l33t".