[Cfrg] draft-irtf-cfrg-argon2 variable-length hash function size

[Matthew Endsley <[e-mail]>]

While implementing argon2 from draft-10, I either incorrectly interpreted a
section or there is an error describing the variable-length hash function
H'.

Section 3.2 lists the operations to perform the Argon2 hash.

This describes the hash function H^x() having an output size of x bytes.

Steps 3 and 4 calculate the initial blocks B[i][0] and B[i][1] as the
result of the variable length hash H'^(128).

I believe this is supposed to be H'^(1024) as the intent is to fill the
entire 1kib block. Using H'^(128) only fills 128 bytes, and generates the
incorrect values for the test vectors. H'^(1024) fills the entire block and
generates the correct values for the test vectors.

Matt