md5.py

def md5(message):
 
    message = bytearray(message) #copy our input into a mutable buffer
    orig_len_in_bits = (8 * len(message)) & 0xffffffffffffffff
    message.append(0x80)
    while len(message)%64 != 56:
        message.append(0)
    message += orig_len_in_bits.to_bytes(8, byteorder='little')
 
    hash_pieces = init_values[:]
 
    for chunk_ofst in range(0, len(message), 64):
        a, b, c, d = hash_pieces
        chunk = message[chunk_ofst:chunk_ofst+64]
        for i in range(64):
            f = functions[i](b, c, d)
            g = index_functions[i](i)
            to_rotate = a + f + constants[i] + int.from_bytes(chunk[4*g:4*g+4], byteorder='little')
            new_b = (b + left_rotate(to_rotate, rotate_amounts[i])) & 0xFFFFFFFF
            a, b, c, d = d, new_b, b, c
        for i, val in enumerate([a, b, c, d]):
            hash_pieces[i] += val
            hash_pieces[i] &= 0xFFFFFFFF
 
    return sum(x<<(32*i) for i, x in enumerate(hash_pieces))