RC4算法Python实现

闲暇之时，用Python实现了一下RC4算法
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1，class方式

#/usr/bin/python#coding=utf-8import sys,os,hashlib,time,base64class 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)

2，function方式

#/usr/bin/python#coding=utf-8import sys,os,hashlib,time,base64def 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)

转自：http://ju.outofmemory.cn/entry/46753