Re: Why do hashes have bigger keys than block ciphers?

On 2011-05-08, MTGAP <mtgandp@xxxxxxxxx> wrote:
I've noticed that modern block ciphers usually have 128-bit or 256-bit
keys, but hashes are usually twice as large (e.g. AES is 128, 192, or
256 bits, but Skein is 256, 512, or 1024 bits). Why are hashes bigger?
Does it have to do with preventing collision attacks?

Hashes in general have no keys at all. If you want to ask why that
particular hash has keys , and why they are so large, that is a
reasonable question and by reading the specification for Skein you can
find out. the size of the key is just the size of the output. AES has no
keys AFAIK. Skein when just used as a hash also has not keys.

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