hashlib的md5计算

hashlib的md5计算

hashlib概述

涉及加密服务：Cryptographic Services
其中 hashlib是涉及 安全散列 和 消息摘要 ，提供多个不同的加密算法借口，如SHA1、SHA224、SHA256、SHA384、SHA512、MD5等。

>>> import hashlib 
>>> m = hashlib.md5() #创建hash对象，md5:(message-Digest Algorithm 5)消息摘要算法,得出一个128位的密文
>>> m.update("Nobody inspects") #更新哈希对象以字符串参数
>>> m.update(" the spammish repetition") #更新哈希对象以字符串参数
>>> m.digest() #返回摘要，作为二进制数据字符串值
>>> m.hexdigest() #返回十六进制数字字符串 

基本用法

hashlib.md5('hiyang').hexdigest()
'97b21efa4d5de4c1a6a2b332f1e183e5'

>>> m = hashlib.md5()
>>> m.update('hiyang')
>>> m.hexdigest()
'97b21efa4d5de4c1a6a2b332f1e183e5'

使用new指定加密算法 new(name, string='')

hashlib.new('md5','hiyang').hexdigest()
'97b21efa4d5de4c1a6a2b332f1e183e5'

h = hashlib.new('md5')
h.update('hiyang')
hashlib.md5('hiyang').hexdigest()
'97b21efa4d5de4c1a6a2b332f1e183e5'

范例

• md5sum() 计算文件的md5
• md5sumd() 计算目录下文件的md5
• md5sumd2() 计算目录下文件的md5，返回一个生成器
• md5CheckFile() 通过md5比较文件内容是否相同

#!/usr/bin/env python
# python 2
# encoding:utf8

import hashlib
import sys
import os

def md5sum(f, readsize=4096):
    """to calculate md5 of a file, readsize default is 4096 bytes
    return result"""
    m = hashlib.md5()
    with open(f, 'rb') as fd:
        data = fd.read(readsize)
        while data:
            m.update(data)
            data = fd.read(readsize)
        else:
            return m.hexdigest()

def md5sumd(filename):
    """to calculate md5 of a directory
    return result"""
    _md5sumd = ''
    for paths, dirs, files in os.walk(filename):
        for f in files:
            fn = os.path.join(paths, f)
            _md5sumd += md5sum(fn)+'  '+fn+'
'
    return _md5sumd

def md5sumd2(filename):
    """to calculate md5 of a directory
    return generator"""
    for paths, dirs, files in os.walk(filename):
        for f in files:
            fn = os.path.join(paths, f)
            yield md5sum(fn)+'  '+fn

def md5CheckFile(filename='.'):
    """calculate md5 of a directory, to check the same file
    return a directory {md5: [filename,...]}, these file has same md5"""
    dic = {}
    for paths, dirs, files in os.walk(filename):
        for f in files:
            fn = os.path.join(paths, f)
            md5 = md5sum(fn)
            if dic.has_key(md5):
                dic[md5].append(fn)
            else:
                dic[md5] = [fn]
        return {k: v for k, v in dic.items() if len(v) >= 2}

if __name__ == '__main__':
    try:
        filename = sys.argv[1]
    except IndexError:
        filename = '.'

    if os.path.isfile(filename):
        print md5sum(filename)+'  '+filename
    elif os.path.isdir(filename):
        _md5sumd = md5sumd(filename)
        print _md5sumd,
        print '-' * 20, 'total', '-' * 20
        print hashlib.md5(_md5sumd).hexdigest()+'  '+filename
    else:
        print >> sys.stderr, 'file %s is not exist.' % filename