Sha256 vulnerability for full rounds
github.com
Sha256 vulnerability for full rounds
1–10 of 12 posts
Re: Sha256 vulnerability for full rounds
#2[deleted]
Re: Sha256 vulnerability for full rounds
#3Same thing that's explained by https://crypto.stackexchange.com/a/48586 ?
TLDR: It's easy to find fixed points of hashes like SHA-256.
Re: Sha256 vulnerability for full rounds
#4How much of a concern is this? Do we now need to use SHA512 for everything, or is this more of an academic vulnerability that we won't see in the wild?
Re: Sha256 vulnerability for full rounds
#5It's unfortunate that proof.py doesn't give an example of a message block that leads from h0 to the q._h constant.
I.e. Free-start collisions don't let you create two PDFs with the same sha256 hash.
Re: Sha256 vulnerability for full rounds
#6How much of a concern is this? Do we now need to use SHA512 for everything, or is this more of an academic vulnerability that we won't see in the wild?
It's not a concern at all. This is not a vulnerability.
Re: Sha256 vulnerability for full rounds
#7Same thing that's explained by https://crypto.stackexchange.com/a/48586 ? TLDR: It's easy to find fixed points of hashes like SHA-256.
Ah, great link. I was not aware of this "feature" of SHA256:
>To abuse this property you need to get the state of the hash to match a state you get when running the decryption of the blockcipher underlying the compression function. Finding such a match requires a meet-in-the-middle attack with cost 2n/2 and thus isn't cheaper than finding a collision.
Re: Sha256 vulnerability for full rounds
#8Same thing that's explained by https://crypto.stackexchange.com/a/48586 ? TLDR: It's easy to find fixed points of hashes like SHA-256.
laie makes it sound like they found two things (free-start collision attack and circular hash attack).
I agree the free-start part isn't very interesting but I don't think we have enough information to confirm or dismiss whether the circular hash attack part is novel.
Re: Sha256 vulnerability for full rounds
#9Same thing that's explained by https://crypto.stackexchange.com/a/48586 ? TLDR: It's easy to find fixed points of hashes like SHA-256.
laie makes it sound like they found two things (free-start collision attack and circular hash attack). I agree the free-start part isn't very interesting but I don't think we have enough information to confirm or dismiss whether the circular hash attack part is novel.
Extraordinary claims require extraordinary evidence, I think it's fair to dismiss those claims until they're capable of coming with a better justification than "I developed an entirely new type of cryptanalysis theory to achieve this."
Re: Sha256 vulnerability for full rounds
#10Same thing that's explained by https://crypto.stackexchange.com/a/48586 ? TLDR: It's easy to find fixed points of hashes like SHA-256.
laie makes it sound like they found two things (free-start collision attack and circular hash attack). I agree the free-start part isn't very interesting but I don't think we have enough information to confirm or dismiss whether the circular hash attack part is novel.
Could you unpack "circular hash attack"? Googling was not very helpful.