Reversing an integer hash function
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Reversing an integer hash function
1–10 of 19 posts
Re: Reversing an integer hash function
#2I'm collecting such inverters at
https://github.com/rurban/smhasher/tree/inverse/inverse
But only 3 so far.
Re: Reversing an integer hash function
#3No post body was provided.
Re: Reversing an integer hash function
#4[deleted]
Re: Reversing an integer hash function
#5Excellent 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".
Re: Reversing an integer hash function
#6Is 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.
Re: Reversing an integer hash function
#7Is 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.
I think the word you are looking for is "permutation".
However, if you can use a permutation as a hash function, you might be fine with just using the identity function.
Re: Reversing an integer hash function
#8Is 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.
This would be a “bijective function” or a “perfect hash function”, although the latter is usually used when the input is much smaller than the output.
Re: Reversing an integer hash function
#9I'm collecting such inverters at https://github.com/rurban/smhasher/tree/inverse/inverse But only 3 so far.
For the cryptopals challenge, you have to invert the Mersenne Twister scramble function:
https://cryptopals.com/sets/3/challenges/23
https://github.com/elsamuko/cryptopals/blob/610ab19bf6823a34...
Re: Reversing an integer hash function
#10I'm collecting such inverters at https://github.com/rurban/smhasher/tree/inverse/inverse But only 3 so far.
I wrote an inverter for XXHASH64, in python: https://gist.github.com/DavidBuchanan314/13020be9e2a251e2a2a...