Timeline for Does preimage resistance and/or collision resistance imply the infeasiblility of finding fixed points in hash functions?
Current License: CC BY-SA 3.0
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| Feb 21, 2018 at 0:04 | comment | added | Luis Casillas | Regarding the edit prompted by @JohnColeman's comment: we know of ways in which standard hash function constructions depart from random functions, and yet we do not consider these breaks. For example, length extensions with Merkle-Damgård, and inner collisions in sponges (although the latter are at least generically hard). Perhaps one way to reformulate John's question is whether a hash function construction with efficiently computable fixpoints would be practically worse than one vulnerable to extensions like M-D. | |
| Feb 20, 2018 at 23:58 | vote | accept | Ian MathWiz | ||
| Feb 20, 2018 at 23:57 | comment | added | Ian MathWiz | Interesting. So it seems that it's not collision or preimage resistance that makes finding fixed points infeasible, but the random oracle nature of a hash function. | |
| Feb 20, 2018 at 23:53 | history | edited | fgrieu♦ | CC BY-SA 3.0 |
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| Feb 20, 2018 at 22:05 | comment | added | John Coleman | This nicely answers the question (+1) but in some ways isn't the most satisfying of examples. Is there an example of a secure hash function which wasn't designed with having a stipulated fixed point in mind which nevertheless has a fixed point which can be feasibly found? Looked at another way, if someone were to come up with a fixed point for SHA-256 itself, would that cause you to question its security? | |
| Feb 20, 2018 at 18:10 | history | edited | Maeher | CC BY-SA 3.0 |
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| Feb 20, 2018 at 18:05 | history | answered | fgrieu♦ | CC BY-SA 3.0 |