Hi Hans-Jürgen

Many thanks for your in-depth review.

I do not agree on this point: this value is used as an output length of a key derivation function algorithm, based on some hash function. The value 128 is perfectly OK for the PBKDF2 particular case. However, a future implementation of PBKDF1 (or some other kdf algorithm) will fail on this dkLen,  because it may constraint to a much lower value, depending on the hash function used. Leaving 8 here was intentional.

See http://tools.ietf.org/html/rfc2898, paragraph 5.1, step 1.