python实现DES加密解密方法实例详解

本文实例讲述了python实现DES加密解密方法。分享给大家供大家参考。具体分析如下：

实现功能：加密中文等字符串
密钥与明文可以不等长
这里只贴代码，加密过程可以自己百度，此处python代码没有优化

1. desstruct.py DES加密中要使用的结构体

ip= (58, 50, 42, 34, 26, 18, 10, 2,
   60, 52, 44, 36, 28, 20, 12, 4,
   62, 54, 46, 38, 30, 22, 14, 6,
   64, 56, 48, 40, 32, 24, 16, 8,
   57, 49, 41, 33, 25, 17, 9 , 1,
   59, 51, 43, 35, 27, 19, 11, 3,
   61, 53, 45, 37, 29, 21, 13, 5,
   63, 55, 47, 39, 31, 23, 15, 7)
ip_1=(40, 8, 48, 16, 56, 24, 64, 32,
   39, 7, 47, 15, 55, 23, 63, 31,
   38, 6, 46, 14, 54, 22, 62, 30,
   37, 5, 45, 13, 53, 21, 61, 29,
   36, 4, 44, 12, 52, 20, 60, 28,
   35, 3, 43, 11, 51, 19, 59, 27,
   34, 2, 42, 10, 50, 18, 58, 26,
   33, 1, 41, 9, 49, 17, 57, 25)
e =(32, 1, 2, 3, 4, 5, 4, 5, 
    6, 7, 8, 9, 8, 9, 10, 11, 
   12,13, 12, 13, 14, 15, 16, 17,
   16,17, 18, 19, 20, 21, 20, 21,
   22, 23, 24, 25,24, 25, 26, 27,
   28, 29,28, 29, 30, 31, 32, 1)
p=(16, 7, 20, 21, 29, 12, 28, 17,
   1, 15, 23, 26, 5, 18, 31, 10, 
   2, 8, 24, 14, 32, 27, 3, 9,
   19, 13, 30, 6, 22, 11, 4, 25)
s=[ [[14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7],
   [0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8],
   [4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0],
   [15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13]],
   [[15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10],
   [3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5],
   [0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15],
   [13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9]],
   [[10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8],
   [13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1],
   [13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7],
   [1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12]],
  [[7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15],
   [13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14,9],
   [10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4],
   [3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14]],
  [[2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9],
   [14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6],
   [4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14],
   [11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3]],
  [[12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11],
   [10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8],
   [9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6],
   [4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13]],
  [[4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1],
   [13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6],
   [1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2],
   [6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12]],
  [[13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7],
   [1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2],
   [7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8],
   [2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11]]]
pc1=(57, 49, 41, 33, 25, 17, 9,
    1, 58, 50, 42, 34, 26, 18,
   10, 2, 59, 51, 43, 35, 27,
   19, 11, 3, 60, 52, 44, 36,
   63, 55, 47, 39, 31, 33, 15,
    7, 62, 54, 46, 38, 30, 22,
   14, 6, 61, 53, 45, 37, 29,
   21, 13, 5, 28, 20, 12, 4);
pc2= (14, 17, 11, 24, 1, 5, 3, 28,
   15, 6, 21, 10, 23, 19, 12, 4, 
   26, 8, 16, 7, 27, 20, 13, 2, 
   41, 52, 31, 37, 47, 55, 30, 40, 
   51, 45, 33, 48, 44, 49, 39, 56, 
   34, 53, 46, 42, 50, 36, 29, 32)
d = ( 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1)

2. des.py 加密文件

#_*_ coding:utf-8 _*_
#!/usr/bin/env python
#Filename:des.py
from desstruct import *
import re
__all__=['desencode']
class DES():
  '''des 加密'''
  def __init__(self):
    pass
  #加密
  def code(self,from_code,key,code_len,key_len):
    output=""
    trun_len=0
    #将密文和密钥转换为二进制
    code_string=self._functionCharToA(from_code,code_len)
    code_key=self._functionCharToA(key,key_len)
    #如果密钥长度不是16的整数倍则以增加0的方式变为16的整数倍
    if code_len%16!=0:
      real_len=(code_len/16)*16+16
    else:
      real_len=code_len
    if key_len%16!=0:
      key_len=(key_len/16)*16+16
    key_len*=4
    #每个16进制占4位
    trun_len=4*real_len
    #对每64位进行一次加密
    for i in range(0,trun_len,64):
      run_code=code_string[i:i+64]
      l=i%key_len
      run_key=code_key[l:l+64]
      #64位明文、密钥初始置换
      run_code= self._codefirstchange(run_code)
      run_key= self._keyfirstchange(run_key)
      #16次迭代
      for j in range(16):
        #取出明文左右32位
        code_r=run_code[32:64]
        code_l=run_code[0:32]
        #64左右交换
        run_code=code_r
        #右边32位扩展置换
        code_r= self._functionE(code_r)
        #获取本轮子密钥
        key_l=run_key[0:28]
        key_r=run_key[28:56]
        key_l=key_l[d[j]:28]+key_l[0:d[j]]
        key_r=key_r[d[j]:28]+key_r[0:d[j]]
        run_key=key_l+key_r
        key_y= self._functionKeySecondChange(run_key)
        #异或
        code_r= self._codeyihuo(code_r,key_y)
        #S盒代替/选择
        code_r= self._functionS(code_r)
        #P转换
        code_r= self._functionP(code_r)
        #异或
        code_r= self._codeyihuo(code_l,code_r)
        run_code+=code_r
      #32互换
      code_r=run_code[32:64]
      code_l=run_code[0:32]
      run_code=code_r+code_l
      #将二进制转换为16进制、逆初始置换
      output+=self._functionCodeChange(run_code)
    return output
  #异或 
  def _codeyihuo(self,code,key):
    code_len=len(key)
    return_list=''
    for i in range(code_len):
      if code[i]==key[i]:
        return_list+='0'
      else:
        return_list+='1'
    return return_list
  #密文或明文初始置换
  def _codefirstchange(self,code):
    changed_code=''
    for i in range(64):
      changed_code+=code[ip[i]-1]
    return changed_code
  #密钥初始置换
  def _keyfirstchange (self,key):
    changed_key=''
    for i in range(56):
      changed_key+=key[pc1[i]-1]
    return changed_key
  #逆初始置换
  def _functionCodeChange(self, code):
    lens=len(code)/4
    return_list=''
    for i in range(lens):
      list=''
      for j in range(4):
        list+=code[ip_1[i*4+j]-1]
      return_list+="%x" %int(list,2)
    return return_list
  #扩展置换  
  def _functionE(self,code):
    return_list=''
    for i in range(48):
      return_list+=code[e[i]-1]
    return return_list   
  #置换P    
  def _functionP(self,code):
    return_list=''
    for i in range(32):
      return_list+=code[p[i]-1]
    return return_list
  #S盒代替选择置换
  def _functionS(self, key):
    return_list=''
    for i in range(8):
      row=int( str(key[i*6])+str(key[i*6+5]),2)
      raw=int(str( key[i*6+1])+str(key[i*6+2])+str(key[i*6+3])+str(key[i*6+4]),2)
      return_list+=self._functionTos(s[i][row][raw],4)
    return return_list
  #密钥置换选择2
  def _functionKeySecondChange(self,key):
    return_list=''
    for i in range(48):
      return_list+=key[pc2[i]-1]
    return return_list
  #将十六进制转换为二进制字符串
  def _functionCharToA(self,code,lens):
    return_code=''
    lens=lens%16
    for key in code:
      code_ord=int(key,16)
      return_code+=self._functionTos(code_ord,4)   
    if lens!=0:
      return_code+='0'*(16-lens)*4
    return return_code
  #二进制转换
  def _functionTos(self,o,lens):
    return_code=''
    for i in range(lens):
      return_code=str(o>>i &1)+return_code
    return return_code
#将unicode字符转换为16进制
def tohex(string):
  return_string=''
  for i in string:
    return_string+="%02x"%ord(i)
  return return_string
def tounicode(string):
  return_string=''
  string_len=len(string)
  for i in range(0,string_len,2):
    return_string+=chr(int(string[i:i+2],16))
  return return_string
#入口函数
def desencode(from_code,key):
  #转换为16进制
  from_code=tohex(from_code)
  key=tohex(key)
  des=DES()
  key_len=len(key)
  string_len=len(from_code)    
  if string_len<1 or key_len<1:
    print 'error input'
    return False
  key_code= des.code(from_code,key,string_len,key_len)
  return key_code
#测试
if __name__ == '__main__':
  print desencode('我是12345678刘就是我abcdwfd','0f1571c947刘')
#返回密文为: 84148584371a6a1fe99e1da0ce1e34649b88ed15098e8aa4b8eb0bf24885c658

3. 解密文件

#_*_coding:utf-8_*_
#!/usr/bin/env python
#Filename:des.py
from desstruct import *
import re
__all__=['desdecode']
class DES():
  '''解密函数，DES加密与解密的方法相差不大
    只是在解密的时候所用的子密钥与加密的子密钥相反
  '''
  def __init__(self):
    pass
  def decode(self,string,key,key_len,string_len):
    output=""
    trun_len=0
    num=0
    #将密文转换为二进制
    code_string=self._functionCharToA(string,string_len)
    #获取字密钥
    code_key=self._getkey(key,key_len)
    #如果密钥长度不是16的整数倍则以增加0的方式变为16的整数倍
    real_len=(key_len/16)+1 if key_len%16!=0 else key_len/16
    trun_len=string_len*4
    #对每64位进行一次加密
    for i in range(0,trun_len,64):
      run_code=code_string[i:i+64]
      run_key=code_key[num%real_len]
      #64位明文初始置换
      run_code= self._codefirstchange(run_code)
      #16次迭代
      for j in range(16):
        code_r=run_code[32:64]
        code_l=run_code[0:32]
        #64左右交换 
        run_code=code_r
        #右边32位扩展置换
        code_r= self._functionE(code_r)
        #获取本轮子密钥
        key_y=run_key[15-j]
        #异或
        code_r= self._codeyihuo(code_r,key_y)
        #S盒代替/选择
        code_r= self._functionS(code_r)
        #P转换
        code_r= self._functionP(code_r)
        #异或
        code_r= self._codeyihuo(code_l,code_r)
        run_code+=code_r
      num+=1
      #32互换
      code_r=run_code[32:64]
      code_l=run_code[0:32]
      run_code=code_r+code_l
      #将二进制转换为16进制、逆初始置换
      output+=self._functionCodeChange(run_code)
    return output
  #获取子密钥
  def _getkey(self,key,key_len):
    #将密钥转换为二进制
    code_key=self._functionCharToA(key,key_len)
    a=['']*16
    real_len=(key_len/16)*16+16 if key_len%16!=0 else key_len
    b=['']*(real_len/16)
    for i in range(real_len/16):
      b[i]=a[:]
    num=0
    trun_len=4*key_len
    for i in range(0,trun_len,64):
      run_key=code_key[i:i+64]
      run_key= self._keyfirstchange(run_key)
      for j in range(16):
        key_l=run_key[0:28]
        key_r=run_key[28:56]
        key_l=key_l[d[j]:28]+key_l[0:d[j]]
        key_r=key_r[d[j]:28]+key_r[0:d[j]]
        run_key=key_l+key_r
        key_y= self._functionKeySecondChange(run_key)
        b[num][j]=key_y[:]
      num+=1
    return b  
  #异或               
  def _codeyihuo(self,code,key):
    code_len=len(key)
    return_list=''
    for i in range(code_len):
      if code[i]==key[i]:
        return_list+='0'
      else:
        return_list+='1'
    return return_list
  #密文或明文初始置换                 
  def _codefirstchange(self,code):
    changed_code=''
    for i in range(64):
      changed_code+=code[ip[i]-1]
    return changed_code
  #密钥初始置换
  def _keyfirstchange (self,key):
    changed_key=''
    for i in range(56):
      changed_key+=key[pc1[i]-1]
    return changed_key
  #逆初始置换
  def _functionCodeChange(self, code):
    return_list=''
    for i in range(16):
      list=''
      for j in range(4):
        list+=code[ip_1[i*4+j]-1]
      return_list+="%x" %int(list,2)
    return return_list
  #扩展置换  
  def _functionE(self,code):
    return_list=''
    for i in range(48):
      return_list+=code[e[i]-1]
    return return_list   
  #置换P  
  def _functionP(self,code):
    return_list=''
    for i in range(32):
      return_list+=code[p[i]-1]
    return return_list
  #S盒代替选择置换  
  def _functionS(self, key):
    return_list=''
    for i in range(8):
      row=int( str(key[i*6])+str(key[i*6+5]),2)
      raw=int(str( key[i*6+1])+str(key[i*6+2])+str(key[i*6+3])+str(key[i*6+4]),2)
      return_list+=self._functionTos(s[i][row][raw],4)
    return return_list
  #密钥置换选择2
  def _functionKeySecondChange(self,key):
    return_list=''
    for i in range(48):
      return_list+=key[pc2[i]-1]
    return return_list
  #将十六进制转换为二进制字符串
  def _functionCharToA(self,code,lens):
    return_code=''
    lens=lens%16
    for key in code:
      code_ord=int(key,16)
      return_code+=self._functionTos(code_ord,4)
    if lens!=0:
      return_code+='0'*(16-lens)*4
    return return_code
  #二进制转换
  def _functionTos(self,o,lens):
    return_code=''
    for i in range(lens):
      return_code=str(o>>i &1)+return_code
    return return_code
#将unicode字符转换为16进制
def tohex(string):
  return_string=''
  for i in string:
    return_string+="%02x"%ord(i)
  return return_string
def tounicode(string):
  return_string=''
  string_len=len(string)
  for i in range(0,string_len,2):
    return_string+=chr(int(string[i:i+2],16))
  return return_string
#入口函数
def desdecode(from_code,key):
  key=tohex(key)
  des=DES()
  key_len=len(key)
  string_len=len(from_code)
  if string_len%16!=0:
    return False
  if string_len<1 or key_len<1:
    return False
  key_code= des.decode(from_code,key,key_len,string_len)
  return tounicode(key_code)
#测试
if __name__ == '__main__':
  print desdecode('84148584371a6a1fe99e1da0ce1e34649b88ed15098e8aa4b8eb0bf24885c658','0f1571c947刘'

解密后为: 我是12345678刘就是我abcdwfd

希望本文所述对大家的Python程序设计有所帮助。