prf.Write(U) U = U[:0] U = prf.Sum(U) for x := range U { T[x] ^= U[x] } } } return dk[:keyLength], nil } func setServiceIndicator(salt []byte, keyLength int) { // The HMAC construction will handle the hash function considerations for the service // indicator. The remaining PBKDF2 considerations outlined by SP 800-132 pertain to // salt and keyLength. // The length of the randomly-generated portion of the salt shall be at least 128 bits. if len(salt) < 128/8 { fips140.RecordNonApproved() } // Per FIPS...