blockLength

Return the "block length" for the hash function. This value is naturally defined for iterated hash functions (Merkle-Damgard). It is used in HMAC (that's what the HMAC specification names the "B" parameter).

If the function is "block-less" then this function may return -n where n is an integer such that the block length for HMAC ("B") will be inferred from the key length, by selecting the smallest multiple of n which is no smaller than the key length. For instance, for the Fugue-xxx hash functions, this function returns -4: the virtual block length B is the HMAC key length, rounded up to the next multiple of 4.