Python实现简单的可逆加密程序实例

#coding=utf-8   
'''''  
    Description: 可逆的加密与解密  
    Environment: python2.5.x  
    Author:idehong@gmail.com  
''' 
import os   
import sys   
class Code(object):   
    '''''可逆的加密与解密''' 
    def __init__(self, key = "idehong@gmail.com"):   
        self.__src_key = key   
        self.__key = self.__get_strascii(self.__src_key, True)   
    def encode(self, value):   
        '''''加密函数, 加密后为一串数字''' 
        return  "%d" % (self.__get_strascii(value, True) ^ self.__key)   
    def decode(self, pwd):   
        '''''解密函数''' 
        if self.is_number(pwd):   
            return self.__get_strascii( (int(pwd)) ^ self.__key, False )   
        else:   
            print 'require number.' 
    def reset_key(self, key):   
        '''''重新设置key''' 
        self.__src_key = key   
        self.__key = self.__get_strascii(self.__src_key, True)   
#===============================================================================   
#        内部调用接口   
#===============================================================================   
    def __get_strascii(self, value, bFlag):   
        if bFlag:   
            return self.__get_str2ascii(value)    
        else:   
            return self.__get_ascii2str(value)   
    def __get_str2ascii(self, value):   
        ls = []   
        for i in value:   
            ls.append( self.__get_char2ascii( i ) )   
        return long("".join(ls))   
    def __get_char2ascii(self, char):   
        '''''获取单个字符的acsii码值''' 
        try:   
            return "%03.d" % ord(char)   
        except (TypeError, ValueError):   
            print "key error." 
            exit(1)   
    def __get_ascii2char(self, ascii):   
        if self.is_ascii_range(ascii):   
            return chr(ascii)   
        else:   
            print "ascii error(%d)" % ascii   
            exit(1)          
    def __get_ascii2str(self, n_chars):   
        ls = []   
        s = "%s" % n_chars   
        n, p = divmod(len(s), 3)   
        if p > 0:   
            nRet = int(s[0 : p])   
            ls.append( self.__get_ascii2char(nRet))   
        pTmp = p   
        while pTmp < len(s):   
            ls.append( self.__get_ascii2char( int(s[pTmp: pTmp + 3])) )
            pTmp += 3 
        return "".join(ls)   
#================================================================================   
#        工具接口   
#================================================================================   
    def is_number(self, value):   
        try:   
            int(value)   
            return True 
        except (TypeError, ValueError):   
            pass 
        return False 
    def is_ascii_range(self, n):   
        return 0 <= n < 256 
    def is_custom_ascii_range(self, n):   
        return 33 <= n <48 or 58 <= n < 126         
class Usage(object):   
    '''''  
    命令行参数读取与解析  
    ''' 
    def __init__(self):   
        self._clsWork = Code()   
        self._args_dic = {'arg_help' : ['-?', '-help'],    
                    'arg_p' : ['-p', '-pwd'],   
                    'arg_t' : ['-t', '-text'],   
                    'arg_k' : ['-k', '-key'],   
                    }           
    def help(self, *k):   
        strHelp = "Usage: pwd [-options] [args...] where option include:" 
        strHelp += """  
        -? -help                    print this help message  
        -k <key_str> -p <pwd_str>  
        -k <key_str> -t <text_str>""" 
        print strHelp     
    def args(self, argv_ls):    
        '''''dispatch command'''    
#        print argv_ls   
        if len(argv_ls) <= 1 or len(argv_ls) > 5:   
            print 'Unrecognized option' 
            return 
        cmd_dic = {}   
        curr_cmd = ''  
        # control command   
        for i, v in enumerate(argv_ls[1:]):   
            for j in self._args_dic.items():   
                # add command   
                if v in j[1] and j[0] not in cmd_dic:   
                    curr_cmd = j[0]   
                    cmd_dic[curr_cmd] = []   
                    break 
            else:   
                # add argv   
                if cmd_dic:   
                    cmd_dic[curr_cmd].append(v)               
        # exec command   
        if cmd_dic:   
            self.exec_cmd(cmd_dic)   
        else:   
            print 'Unrecognized option' 
    def exec_cmd(self, cmd_dic):     
        '''''exec cmd'''        
        if len(cmd_dic) == 2:   
            if 'arg_p' in cmd_dic and 'arg_k' in cmd_dic\   
                and len(cmd_dic['arg_p']) == 1 and len(cmd_dic['arg_k']) == 1:   
                self._clsWork.reset_key(cmd_dic['arg_k'][0])   
                print self._clsWork.encode(cmd_dic['arg_p'][0])   
                return 
            elif 'arg_t' in cmd_dic and 'arg_k' in cmd_dic\   
                and len(cmd_dic['arg_t']) == 1 and len(cmd_dic['arg_k']) == 1:   
                self._clsWork.reset_key(cmd_dic['arg_k'][0])   
                print self._clsWork.decode(cmd_dic['arg_t'][0])   
                return 
        self.help()   
if __name__ == '__main__':   
    usage = Usage()   
    usage.args(sys.argv)