Hot answers tagged hkdf
3
There are two answers: the "engineering" answer, and the "principled" answer.
The engineering answer is that, in practice, if you generate two keys using two different info strings, I suspect you'd probably get away with it without problems. If we model the hash as a random oracle (admittedly a very strong "assumption"), then I suspect it might be possible ...
3
A key derivation function is intuitively "purifying" the entropy in the group element Z into uniformly random (looking) bits that can used as a key for other purposes. It is not designed to produce "multiple keys" from the same Z, and one should definitely not call the KDF on the same Z twice (even with different salts) and expect to get two independent ...
2
No, you don't have to worry about collisions.
As long as no pair of users have the same LowEntropy input, they will receive different MasterKeys. If the MasterKey is different, then the AuthKey will be different. Even if you use the same MasterKey to generate multiple AuthKeys, you don't need to worry about collisions: as long as the keynumber values are ...
1
No, the info is not a salt. The input key material for a KBKDF (key based key derivation function) should already be pseudo-random, and should therefore contain enough entropy to not need a salt.
If the user already has a unique 16+ pseudo-random bytes key then there is little reason to use the email address as part of the info. The email address could be ...
Only top voted, non community-wiki answers of a minimum length are eligible
