def modify_key_parity(key):
    """
    The prior use of the function is to return the parity-validated key.

    The incoming key is expected to be hex data binary representation, e.g. b'E7A3C8B1'
    """
    validated_key = b''
    for byte in key:
        if parityOf(int(byte)) == -1:
            byte_candidate = int(byte) + 1 
            while parityOf(byte_candidate) == -1:
                byte_candidate = divmod(byte_candidate + 1, 256)[1]
            validated_key += bytes([byte_candidate])

        else:
            validated_key += bytes([byte])
    return validated_key