Function get_block_words

hashes/md5.py:134–187

Splits bit string into blocks of 512 chars and yields each block as a list of 32-bit words Example: Suppose the input is the following: bit_string = "000000000...0" + # 0x00 (32 bits, padded to the right) "000000010...0" + # 0x01 (32 bits, padded to th

(bit_string: bytes)

def get_block_words(bit_string: bytes) -> Generator[list[int]]:
    """
    Splits bit string into blocks of 512 chars and yields each block as a list
    of 32-bit words

    Example: Suppose the input is the following:
        bit_string =
            "000000000...0" +  # 0x00 (32 bits, padded to the right)
            "000000010...0" +  # 0x01 (32 bits, padded to the right)
            "000000100...0" +  # 0x02 (32 bits, padded to the right)
            "000000110...0" +  # 0x03 (32 bits, padded to the right)
            ...
            "000011110...0"    # 0x0a (32 bits, padded to the right)

        Then len(bit_string) == 512, so there'll be 1 block. The block is split
        into 32-bit words, and each word is converted to little endian. The
        first word is interpreted as 0 in decimal, the second word is
        interpreted as 1 in decimal, etc.

        Thus, block_words == [[0, 1, 2, 3, ..., 15]].

    Arguments:
        bit_string {[string]} -- [bit string with multiple of 512 as length]

    Raises:
        ValueError -- [length of bit string isn't multiple of 512]

    Yields:
        a list of 16 32-bit words

    >>> test_string = ("".join(format(n << 24, "032b") for n in range(16))
    ...                  .encode("utf-8"))
    >>> list(get_block_words(test_string))
    [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]]
    >>> list(get_block_words(test_string * 4)) == [list(range(16))] * 4
    True
    >>> list(get_block_words(b"1" * 512)) == [[4294967295] * 16]
    True
    >>> list(get_block_words(b""))
    []
    >>> list(get_block_words(b"1111"))
    Traceback (most recent call last):
    ...
    ValueError: Input must have length that&#x27;s a multiple of 512
    """
    if len(bit_string) % 512 != 0:
        raise ValueError("Input must have length that's a multiple of 512")

    for pos in range(0, len(bit_string), 512):
        block = bit_string[pos : pos + 512]
        block_words = []
        for i in range(0, 512, 32):
            block_words.append(int(to_little_endian(block[i : i + 32]), 2))
        yield block_words


def not_32(i: int) -> int: