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md5.py
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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# md5.py
#
# Copyright 2017 SnDream <[email protected]>
#
# 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 2 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, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA 02110-1301, USA.
#
#
# 限于python特性，无法实现加溢出，计算加法后需要适时计算模32来手动截断
# 模32改用与实现时的参数，专门命名简短程序长度
M32 = 0xFFFFFFFF
# IV表
# ABCD的预设值，注意是小端序
IV_TABLE = [
0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476]
# T表
# 数据与sin有关，由于数值固定，故建表
T_TABLE = [
0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05,
0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391]
# 移位表
# 每次左循环移位的位数
S_TABLE = [
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]
# X索引表
# 每次读取X的段号
XNO_TABLE = [
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
1, 6, 11, 0, 5, 10, 15, 4, 9, 14, 3, 8, 13, 2, 7, 12,
5, 8, 11, 14, 1, 4, 7, 10, 13, 0, 3, 6, 9, 12, 15, 2,
0, 7, 14, 5, 12, 3, 10, 1, 8, 15, 6, 13, 4, 11, 2, 9]
def main(args):
# 主程序，通过命令行执行时附加参数作为输入
# 输入：N个文件名
# 输出：每个文件名对应文件的md5值
# 输出格式模仿md5sum，但没有实现其读取标准流的功能
# 限于Python特性（无法做加法溢出，需要手动截断）效率也相当低
# 虽然考虑了大文件读入的问题，但是大文件的计算本身效率很差
# 因此以按本程序结构，重写C语言版本
# 计算400MB数据：md5sum用时2.8s md5.c用时6.0s md5.py用时9m17s
if len(args) == 1: # 当没有传入文件参数时，直接提示用法并返回
print('Usage: md5.py [FILE]...')
print('Print MD5 (128-bit) checksums.')
return -1
for filename in args[1::]:
try:
ABCD = IV_TABLE
filesize = 0
with open(filename, 'rb') as rawdata:
chunk = rawdata.read(64)
while len(chunk) == 64: # 非末尾文件块，循环处理
ABCD = HMD5(ABCD, chunk)
filesize += 64
chunk = rawdata.read(64)
# 到这里为止计算的文件大小实际上是Byte大小，md5按Bit大小记录，需要重算
filesize = ((filesize + len(chunk)) << 3) & ((1 << 64) - 1)
# 已处理到末尾文件块，生成其余部分
chunk += b'\x80'
if len(chunk) > 56: # 当其余部分不足以放下文件长度时，需要再生成一个一块
chunk += bytes([0] * (64 - len(chunk)))
ABCD = HMD5(ABCD, chunk)
chunk = bytes([0] * 56)
else:
chunk += bytes([0] * (56 - len(chunk)))
chunk += filesize.to_bytes(8, byteorder='little', signed=False)
ABCD = HMD5(ABCD, chunk)
md5sum_bytes = b''
md5sum = ''
for i in ABCD:
md5sum_bytes += i.to_bytes(4, 'little', signed=False)
for byte in md5sum_bytes:
md5sum += "%02x" % byte
print(md5sum, '', filename)
except FileNotFoundError as e:
print('No such file:', filename)
return 0
def HMD5(ABCD, chunk):
# HMD5函数，核心函数
# 输入：ABCD的list(4个数 各32bit) 文件块(512bit)
# 输出：ABCD的list(4个数 各32bit)
A, B, C, D = ABCD[0], ABCD[1], ABCD[2], ABCD[3]
X = []
for i in range(0, 64, 4):
X.append(
int.from_bytes(chunk[i:i + 4], byteorder='little', signed=False))
for i in range(0, 64):
A, B, C, D = D, (
rol((A + FGHI(B, C, D, i) + X[XNO_TABLE[i]] + T_TABLE[i]) & M32, S_TABLE[i]) + B) & M32, B, C
return [(A + ABCD[0]) & M32, (B + ABCD[1]) & M32, (C + ABCD[2]) & M32, (D + ABCD[3]) & M32]
def FGHI(B, C, D, i):
# F G H I四个函数
# 输入：B C D 轮次
# 输出：根据轮次选择对应的函数，计算结果并返回
if i < 16:
return ((B & C) | (~B & D)) & M32
elif i < 32:
return ((B & D) | (C & ~D)) & M32
elif i < 48:
return (B ^ C ^ D) & M32
elif i < 64:
return (C ^ (B | ~D)) & M32
else:
raise Exception("Not F,G,H or I")
def rol(value, times):
# 简单32位循环左移
# 输入：原值 左移次数
# 输出：左移结果
return ((value << times) | (value >> (32 - times))) & M32
if __name__ == '__main__':
import sys
sys.exit(main(sys.argv))