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Results tagged with sha-256
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user 13541
SHA-256 is part of the SHA-2 family of hash functions with a 256-bit output and a 128-bit security level.
2
votes
Accepted
If you know the messages, and the results of HMAC(key, message) can you find the key?
Not, that should be not possible, at least if you have a good key.
All this is only valid as long as SHA-256 is still a secure hash algorithm and not broken. To be precise, as long as HMAC-SHA-256 is …
- 3,900
5
votes
Why SHA-256 (or any other) is too fast for passwords but "slow" for collisions to be found?
If one hash takes 2 nanoseconds, $2^{42}$ hashes are fast to compute - you can do that in under 3 hours. But what if you want to try $2^{128}$ hashes? Even with one billion times the computational pow …
- 3,900
3
votes
Accepted
Is the result of HMAC-sha256 distinguishable from random noise?
If the keys and messages are known, yes, you can distinguish which were used - because you can test them all. If not, then this is "sligtly harder" (= not really possible with big enough values). Anyt …
- 3,900
32
votes
How can hashes be unique if they are limited in number?
You are right, hashes won't be all unique as you already have shown. The important part are practical collisions - how many SHA-512 hashes can the whole earth generate in its lifetime? Definitely much …
- 3,900