RC4算法Python实现

闲暇之时,用Python实现了一下RC4算法

编码 UTF-8

class 方式

#/usr/bin/python
#coding=utf-8

import sys,os,hashlib,time,base64
class rc4:

    def __init__(self,public_key = None,ckey_lenth = 16):
        self.ckey_lenth = ckey_lenth
        self.public_key = public_key or 'none_public_key'
        key = hashlib.md5(self.public_key).hexdigest()
        self.keya = hashlib.md5(key[0:16]).hexdigest()
        self.keyb = hashlib.md5(key[16:32]).hexdigest()
        self.keyc = ''

    def encode(self,string):
        self.keyc = hashlib.md5(str(time.time())).hexdigest()[32 - self.ckey_lenth:32]
        string = '0000000000' + hashlib.md5(string + self.keyb).hexdigest()[0:16] + string
        self.result = ''
        self.docrypt(string)
        return self.keyc + base64.b64encode(self.result)

    def decode(self,string):
        self.keyc = string[0:self.ckey_lenth]
        string = base64.b64decode(string[self.ckey_lenth:])
        self.result = ''
        self.docrypt(string)
        result = self.result
        if (result[0:10] == '0000000000' or int(result[0:10]) - int(time.time()) > 0) and result[10:26] == hashlib.md5(result[26:] + self.keyb).hexdigest()[0:16]:
            return result[26:]
        else:
            return None

    def docrypt(self,string):
        string_lenth = len(string)
        result = ''
        box = list(range(256))
        randkey = []

        cryptkey = self.keya + hashlib.md5(self.keya + self.keyc).hexdigest()
        key_lenth = len(cryptkey)

        for i in xrange(255):
            randkey.append(ord(cryptkey[i % key_lenth]))

        for i in xrange(255):
            j = 0
            j = (j + box[i] + randkey[i]) % 256
            tmp = box[i]
            box[i] = box[j]
            box[j] = tmp

        for i in xrange(string_lenth):
            a = j = 0
            a = (a + 1) % 256
            j = (j + box[a]) % 256
            tmp = box[a]
            box[a] = box[j]
            box[j] = tmp
            self.result += chr(ord(string[i]) ^ (box[(box[a] + box[j]) % 256]))

测试:

rc = rc4('nishidahuaidan')
string = '我在这里呢,你在那里呢'
print(string)
str = rc.encode(string)
print(str)
str = rc.decode(str)
print(str)

function方式

#/usr/bin/python
#coding=utf-8

import sys,os,hashlib,time,base64

def rc4(string, op = 'encode', public_key = 'ddd', expirytime = 0):
    ckey_lenth = 4
    public_key = public_key and public_key or ''
    key = hashlib.md5(public_key).hexdigest()
    keya = hashlib.md5(key[0:16]).hexdigest()
    keyb = hashlib.md5(key[16:32]).hexdigest()
    keyc = ckey_lenth and (op == 'decode' and string[0:ckey_lenth] or hashlib.md5(str(time.time())).hexdigest()[32 - ckey_lenth:32]) or ''
    cryptkey = keya + hashlib.md5(keya + keyc).hexdigest()
    key_lenth = len(cryptkey)
    string = op == 'decode' and base64.b64decode(string[4:]) or '0000000000' + hashlib.md5(string + keyb).hexdigest()[0:16] + string
    string_lenth = len(string)

    result = ''
    box = list(range(256))
    randkey = []

    for i in xrange(255):
        randkey.append(ord(cryptkey[i % key_lenth]))

    for i in xrange(255):
        j = 0
        j = (j + box[i] + randkey[i]) % 256
        tmp = box[i]
        box[i] = box[j]
        box[j] = tmp

    for i in xrange(string_lenth):
        a = j = 0
        a = (a + 1) % 256
        j = (j + box[a]) % 256
        tmp = box[a]
        box[a] = box[j]
        box[j] = tmp
        result += chr(ord(string[i]) ^ (box[(box[a] + box[j]) % 256]))

    if op == 'decode':
        if (result[0:10] == '0000000000' or int(result[0:10]) - int(time.time()) > 0) and result[10:26] == hashlib.md5(result[26:] + keyb).hexdigest()[0:16]:
            return result[26:]
        else:
            return None
    else:
        return keyc + base64.b64encode(result)

测试:

string = '我在这里呢,你在那里呢'
print(string)
str = rc4(string,'encode')
print(str)
rc = rc4(str,'decode')
print(rc)