New answers tagged collision-resistance
1
By all accounts SHA-512/160 is more secure than SHA1.
The only question is it secure enough?
If you are only worried about preimage or second preimage resistance the answer is yes. 160 bits should be sufficient for the forseeable future even faced against powerfull adversaries.
If you need collision resistance the answer gets more complicated. There are no ...
0
It is as safe as SHA-1 was initially supposed to be. The same would be true of most other notable secure hash functions with digests truncated to 160 bits.
Crucially, though, the security of the resulting algorithm is always limited to 160-bit pre-image resistance and 80-bit collision resistance. It doesn't matter how much higher SHA-512 or another hash ...
2
It's certainly better to move to a modern hash function without significant known weaknesses than to stick with one that is known to be broken. Furthermore using a larger state for the hashing process helps mitigate certain attacks, even if your output size is limited.
In an ideal world you would make the system support longer hashes, but if the choice is ...
3
Generic collisions
The generic collision attack on SHA-512 trimmed to $n=160$-bit will require $2^{80}$ complexity by the birthday paradox with a 50% success probability. The generic attack doesn't require any knowledge about the internals of the target hash function. It is about collecting hash outputs and looking collision among them by building a table ...
29
a. No such double hashing doesn't do a bit of good. Anything which collides after a single hash will definetly collide after a double hash. It preserves all collisions and adds new ones.
We might consider other constructions which may provide some strength e.g $H(H(m) || m)$ however:
b. We have no need for any such double hashing of SHA1 as we have newer ...
1
It depends a lot of why you want to do this and for what types of hashes and input data but I would think that for some purposes it may be sufficient to do so through sampling, though you would certainly want to be careful about how much you trust this sort of analysis depending on how you're using the hash values.
For example, if you know that the data you'...
5
We can consider Merkle-Damgard(MD) based hash functions like MD4, MD5, SHA-1, SHA-256, SHA-512, and derivatives as a rotated block cipher, where the key is the message and the input is the previous state.
A bit more formally, for SHA-1, there is a block cipher, named SHACAL, that takes a 512-bit key and 160-bit block as the input. Then the MD construction ...
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