python简单的可逆加密程序

简单加密，用python来写写。
#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