Python中实现的RC4算法

#/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]))

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)

#/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)

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)