def calculate_hamming_distance(input_bytes_1, input_bytes_2):
    """Finds and returns the Hamming distance (number of differing 
    bits) between two byte-strings
    """
    hamming_distance = 0
    for b1, b2 in zip(input_bytes_1, input_bytes_2):
        difference = b1 ^ b2

        # Count the number of differences ('1's) and add to the hamming distance
        hamming_distance += sum([1 for bit in bin(difference) if bit == '1'])
    return hamming_distance