Timeline for Is SHA-256 bijective on a certain domain?
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
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| Apr 3, 2021 at 15:46 | vote | accept | Roman Gherta | ||
| Apr 2, 2021 at 8:47 | comment | added | Roman Gherta | Paul, related to your last paragraph: It is perfectly acceptable and practiced to restrict domains to make functions invertible, this is not cheating. But I am probably too lazy to follow though with this and the idea that an inverse exists, is enough for me, unless there is a big fundamental problem with this entire approach. Pre-image resistance problem(crypto term) we remove as discussed by eliminating collisions(I wish) and by making the range so small that it is actually feasible for my laptop to make these computations.... | |
| Apr 1, 2021 at 22:36 | history | edited | Paul Uszak | CC BY-SA 4.0 |
Longer answer given more time.
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| Apr 1, 2021 at 17:56 | comment | added | Roman Gherta | Applications... I guess it would be a first to say that you found a function sha256inv defined on a specific domain of hashes(the codomain/image computed above... maybe there is something special about that domain) for which sha256inv(hash)=string . And you can do this analytically without saving all these hashes as a map in some database. | |
| Apr 1, 2021 at 17:56 | comment | added | Roman Gherta | So i need to compute the function Image... You are saying this to be sure the function is also surjective... So if I define the function as sha256prime() : 2^29 -> 2^256 , then this function is not surjective and definetely no inverse exists. And this is why I need to basicaly... brute force a 2^29 codomain. This way the function definitely has an and only one inverse and I can bother reading the algorithm of sha256 to search for compositions etc. | |
| Apr 1, 2021 at 16:16 | comment | added | hola | "a cryptographic use for such strange domains" - privacy preserving encryption would make sense? | |
| Apr 1, 2021 at 15:31 | history | edited | Paul Uszak | CC BY-SA 4.0 |
added 168 characters in body
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| Apr 1, 2021 at 15:25 | history | answered | Paul Uszak | CC BY-SA 4.0 |