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)