Hash @args into a BigInt using a cryptographic hash function.

def hashZ(*args):
    """
    Hash @args into a BigInt using a cryptographic hash function.
    """
    TAG = "TAG_RELIC_HASH_Z"
    MESSAGE = "MESSAGE_HASH_Z"

    # Combine the arguments into a canonical string representation.
    text = TAG.join([str(val) for val in args ] )

    # Hash the string using HMAC
    # b: byte string 
    b = hmac(text, MESSAGE)
    return BigInt(longFromString(b))