md5.py

# MD5 Python 2 implementation
# coding=UTF-8
# Copyright (C) 2013  Filippo Valsorda
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# Originally based, even if no code survives, on a Python license work
# by Dinu C. Gherman (C) 2001 and Aurelian Coman
# http://starship.python.net/crew/gherman/programs/md5py/md5py.py

import struct
import binascii
import math

lrot = lambda x, n: (x << n) | (x >> (32 - n))


class MD5():

    A, B, C, D = (0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476)

    # r specifies the per-round shift amounts
    r = [7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22,
         5,  9, 14, 20, 5,  9, 14, 20, 5,  9, 14, 20, 5,  9, 14, 20,
         4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23,
         6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21]

    # Use binary integer part of the sines of integers (Radians) as constants
    k = [int(math.floor(abs(math.sin(i + 1)) * (2 ** 32))) for i in range(64)]

    def __init__(self, message):
        # MD5 works in 512 bit (64 byte) blocks. Apply padding and process each block.
        length = struct.pack('<Q', len(message) * 8)
        message += '\x80'
        message += '\x00' * ((64 - len(length) - (len(message) % 64)) % 64)
        message += length

        assert len(message) % 64 == 0

        while len(message):
            # Bite off whole 64-character chunks and handle them.
            self._handle(message[:64])
            message = message[64:]

    def _handle(self, chunk):
        w = list(struct.unpack('<' + 'I' * 16, chunk))

        a, b, c, d = self.A, self.B, self.C, self.D

        for i in range(64):
            if i < 16:
                f = (b & c) | ((~b) & d)
                g = i
            elif i < 32:
                f = (d & b) | ((~d) & c)
                g = (5 * i + 1) % 16
            elif i < 48:
                f = b ^ c ^ d
                g = (3 * i + 5) % 16
            else:
                f = c ^ (b | (~d))
                g = (7 * i) % 16

            x = b + lrot((a + f + self.k[i] + w[g]) & 0xffffffff, self.r[i])
            a, b, c, d = d, x & 0xffffffff, b, c

        self.A = (self.A + a) & 0xffffffff
        self.B = (self.B + b) & 0xffffffff
        self.C = (self.C + c) & 0xffffffff
        self.D = (self.D + d) & 0xffffffff

    def digest(self):
        return struct.pack('<IIII', self.A, self.B, self.C, self.D)

    def hexdigest(self):
        return binascii.hexlify(self.digest()).decode()

if __name__ == "__main__":
    s1 = 'thequickbrownfoxjumpedoverthelazydog'
    assert MD5(s1).hexdigest() == 'df14e4d5469e801dbc8e1df4eebd97b3'
    s2 = '\xff\xff'
    assert MD5(s2).hexdigest() == 'ab2a0d28de6b77ffdd6c72afead099ab'
    s3 = '😦 😧 😈 👿 😮 😬 😐 😕 😯 😶 😇 😏'
    assert MD5(s3).hexdigest() == '83162541e5329195409c925314250bc5'
    print 'It works!'