Just to add some context to Howard Chu's message from Sat, 25 Feb 2017,
I'd like to point out that the scrypt settings chosen for litecoin PoW,
which I think are the ones commercial mining hardware are optimized for, are
some orders of magnitude different than the ones recommended for user
authentication, and are not, in my humble opinion, a sufficient reason to
exclude the scrypt construct from consideration:
- https://litecoin.info/Scrypt
uses N = 1024, r = 1, p = 1
which means using
1024 * 1 * 1 * 128 = 128 KiBytes bytes of memory
and doing
2 * (1024 * 1) = 2 Ki hashing rounds
- the traditional default values for the parameters are
N = 16384, r = 8, p = 1 , which means using
2^16 * 8 * 1 * 128 = 16 MiBytes of memory
and doing
32Ki hashing rounds
and these values can be customized (almost) at will to increase both the
computational effort and the memory footprint of the password hashing; e.g.
libsodium's crypto_pwhash_scryptsalsa208sha256 sets N = 2^20 in the
"{OPS,MEM}LIMIT_SENSITIVE" case, leading to a memory occupation of 1GiB and
an hashing rounds count of 2 * 2^20.