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Python实现DES加密算法的文本加密器

这是自行制作的一个DES文本加密工具

最终效果图:

技术分享

 

本加密器支持UTF-8字符的加解密(包含中文),由于其中的编码方式与常用编码方式不同,加密结果与网上工具不同,但是能实现正常加解密。

最终目标:

目的是设计一个基于ECB模式,短块加密使用填充法的DES加密解密器,以此来实现对文本的加解密,其文本的处理还用到了base64编码。

实验内容:

des加密软件我采用的是python语言编写。主程序分了四个大的模块,

一个负责图形化界面的编写及综合作用的mainfunc.py文件;

一个负责DES的加解密的DES.py文件;

一个负责字符串的处理以及base64编码的handle.py文件;

最后一个setup.py用于打包程序

以下将做详细介绍。

 

 

首先来介绍软解加解密的主要流程

对秘钥的处理:

  由于用户输入的秘钥是8个字符,故首先要将其转化为64位的二进制字符串,该功能由handle.py中的keyencode函数实现:

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加密流程:

1用户输入的明文为任意字符串(包含中文字符以及英文字母以及标点符号),首先要进行分组处理,分组成64位二进制一组的二进制字符串,最后一组不足64位的使用填充法,该部分由handle.py中的encode函数处理

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2 接着根据之前得到的64位秘钥以及明文,依次进行DES加密,得到包含所有64位密文的数组

3 接着要将各64位的密文连在一起得到二进制的密文字符串,再对其进行base64编码得到最终的输出字符串,该部分由handle.py中的base64encode函数处理。

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解密流程:

1 解密首先要对得到的密文字符串进行反base64编码处理,去掉后面添加的‘=’,接着将其根据base64的编码规则转化为二进制字符串,然后去掉之前添加的‘0’字符,然后将字符串进行分组,分为64位一组。这一部分由handle.py中的base64decode函数完成。

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2接着根据之前得到的64位秘钥以及密文,依次进行DES解密,得到包含所有64位明文的数组。

3接着要对得到的包含所有64位明文的数组进行处理,首先去掉之前填充的多余的字符,接着对二进制字符串进行反编码得到源字符串。该部分由handle.py中的decode函数得到。

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DES部分: 

接着来编写DES加密模块,DES加解密流程完全按照书本上DES加解密流程实现,实现过程也没有什么难点,在此就不做过多介绍。

 

实验难点:

 本次实验的DES加解密编程较为顺利,在字符串的操作上开始遇到了一点困难,之后比较顺利。主要是在字符串与二进制串的转换,字符编码上遇到了一些问题。

 

1.填充法的选择

 由于初始的明文转化为64位二进制字符串后,最后一组并不一定是64位,故要进行处理,我这里运用的是比较直观的填充法,具体是PKCS5方法,在PKCS5方法中Block = 8bytesPadding特点:对于Block=8bytes(64bits)进行填充字节的值的取值范围在[1, 8].解码过程中,从最后一个字节看起,首先确定它表示的值1<=n<=8,然后检验最后n个字节的值是否相同,若相同最后删去最后n个字节即可得到完整的信息.特殊情况:若字符串恰好够分成完整的块,不多不少.则最后8个字节为:(IN HEX) 08 08 08 08 08 08 08 08

 我在代码中已经实现:

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2.中英文编码

   这个问题实则比较麻烦,在我使用的python2.7版本中默认英文字符占一个字节,即八位,中文字符占据两个字节,即两个字节。如果中英文混在一起将无法区分。

   一开始,我想到的解决方法是将中文字符16位中最高位置1,因为英文8位最高位为0,故可以将其区分,解码时在进行还原。但结果发现,有一部分中文字符最高位为0,故此法不通。

   因此,我只好将英文字符也扩展到16位,高8位置0,我最终的代码也按此实现,但是此方法对加密的安全性应该有一定的影响。例如,对于全英文的文本,所需要破解的字符串瞬间减到一半。

但暂时没有想到更好的方法。

   以下为我的代码实现:

 技术分享

 

附上最终源码:

mainfunc.py

#-*- coding=utf-8 -*-
import wx
import wx.lib.buttons as buttons
from lib import DES
from lib import handle

class newframe(wx.Frame):
    def __init__(self):     #主框架
        wx.Frame.__init__(self,None,-1,u‘DES加解密工具‘,size=(820,760),pos=(500,100))
        self.SetMinSize((820,760))
        self.SetMaxSize((820,760))
        self.panel=wx.Panel(self,-1)
        self.panelpic=wx.Image(‘./diary.jpg‘,wx.BITMAP_TYPE_JPEG,).Scale(820,760).ConvertToBitmap()
        self.picbk=wx.StaticBitmap(parent=self.panel,pos=(0,0),bitmap=self.panelpic)
        self.initstatictext()
        self.textctrl()
        self.buttoninit()
        self.buttonbind()
    def initstatictext(self):       #定义文本
        self.text1=wx.StaticText(self.picbk,-1,u‘请输入加解密秘钥(仅八位长):‘,pos=(40,10),size=(-1,25),style=wx.TE_CENTER)#,size=(240,25))
        self.text2=wx.StaticText(self.picbk,-1,u‘未加密文本:‘,pos=(40,60),size=(-1,25),style=wx.TE_CENTER)#,size=(240,25))
        self.text3=wx.StaticText(self.picbk,-1,u‘加密后文本:‘,pos=(40,400),size=(-1,25),style=wx.TE_CENTER)#,size=(240,25))
        self.text1.SetBackgroundColour(‘AQUAMARINE‘)
        self.text2.SetBackgroundColour(‘AQUAMARINE‘)
        self.text3.SetBackgroundColour(‘AQUAMARINE‘)
    def textctrl(self):     #定义文本框
        font2 = wx.Font(12, wx.DECORATIVE, wx.NORMAL, wx.NORMAL)
        self.ctrl1=wx.TextCtrl(self.picbk,-1,‘‘,pos=(30,100),size=(750,250), style=wx.TE_MULTILINE|wx.TE_RICH2)
        self.ctrl1.SetBackgroundColour(‘sky blue‘)
        self.ctrl1.SetFont(font2)
        self.ctrl2=wx.TextCtrl(self.picbk,-1,‘‘,pos=(270,10),size=(150,28))
        self.ctrl2.SetBackgroundColour(‘sky blue‘)
        self.ctrl2.SetFont(font2)
        self.ctrl3=wx.TextCtrl(self.picbk,-1,‘‘,pos=(30,450),size=(750,250), style=wx.TE_MULTILINE|wx.TE_RICH2)
        self.ctrl3.SetBackgroundColour(‘sky blue‘)
        self.ctrl3.SetFont(font2)
    def buttoninit(self):   #定义按钮
        self.button1=buttons.GenButton(self.picbk,-1,u‘加密‘,pos=(240,380),size=(-1,50))
        self.button2=buttons.GenButton(self.picbk,-1,u‘解密‘,pos=(540,380),size=(-1,50))
        self.button1.SetBezelWidth(5)
        self.button2.SetBezelWidth(5)
        self.button1.SetBackgroundColour("CORAL")
        self.button2.SetBackgroundColour("CORAL")
    def buttonbind(self):   #按钮事件绑定
        self.button1.Bind(wx.EVT_BUTTON,self.encode)
        self.button2.Bind(wx.EVT_BUTTON,self.decode)
    def encode(self,evt): #加密事件
        out=[]
        password=self.ctrl2.GetValue()
        password=handle.keyencode(password)
        text=self.ctrl1.GetValue()
        text=handle.encode(text)
        for one in text:
            a=DES.desencode(password,one)
            out.append(a)
        cipher=handle.base64encode(out)
        self.ctrl3.SetLabelText(cipher)
    def decode(self,evt): #解密事件
        cipherlist=[]
        outlist=[]
        password=self.ctrl2.GetValue()
        password=handle.keyencode(password)
        ciphertext=self.ctrl3.GetValue()
        cipherlist=handle.base64decode(ciphertext)
        for one in cipherlist:
            outlist.append(DES.desdecode(password,one))
        outstring=handle.decode(outlist)
        self.ctrl1.SetLabelText(outstring)

if __name__==‘__main__‘:
    newapp=wx.App(False)
    frame=newframe()
    frame.Show()
    newapp.MainLoop()

  handle.py

#-*- coding=utf-8 -*-

base=‘ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/‘


def keyencode(key):  #该部分将秘钥串转化为64位二进制形式
    out=‘‘
    for i in key:   #将每一个字符转化为二进制形式
        out+=str(bin(ord(i))).replace(‘0b‘,‘‘).zfill(8)
    return out

def encode(string):     #该部分主要是将明文字符串转化为每64位一组二进制明文
    out1=‘‘
    text=[]
    for i in string:    #将每一个字符转化为二进制
        temp=str(bin(ord(i))).replace(‘0b‘,‘‘)
        out1+=temp.zfill(16)
    time=len(out1)/64
    for i in range(time+1): #对二进制字符串进行分组,每64位一组
        text.append(out1[64*i:64*(i+1)])
    length=len(text[time])
    if length!=64:    #最后一组如果不满64位进行填充
        add=8-length/8
        text[time]+=str(bin(ord(str(add)))).replace(‘0b‘,‘‘).zfill(8)*add
    else:
        text.append(str(bin(ord(‘8‘))).replace(‘0b‘,‘‘).zfill(8)*8)
    return text

def base64encode(list):  #该部分主要是对二进制串进行base64处理
    out=‘‘
    string=‘‘.join(list)
    a=len(string)%24
    if a==8:                #补0操作
        string+=‘0000‘
    if a==16:
        string+=‘00‘
    m=int(len(string)/6)
    for j in range(m):
        out+=base[int(string[j*6:j*6+6],2)]
    if(a==8):               #补=操作
        out+=‘==‘
    if(a==16):
        out+=‘=‘
    return out

def base64decode(string):   #该部分主要进行base64解码操作
    temp1=string.split(‘=‘)[0]  #去掉多余的=
    temp2=‘‘
    outlist=[]
    for i in temp1:         #将字符串转化为二进制串
        temp2+=str(bin(base.index(i))).replace(‘0b‘,‘‘).zfill(6)
    temp3=len(temp2)
    if (temp3-2)%64==0:     #去掉多余的0
        temp2=temp2[0:len(temp2)-2]
    if (temp3-4)%64==0:
        temp2=temp2[0:len(temp2)-4]
    time=len(temp2)/64
    for i in range(time):   #将二进制串每64位进行分组
        outlist.append(temp2[64*i:64*(i+1)])
    return outlist

def decode(list1):  #该部分主要是将64位明文转化为原字符串
    string=‘‘
    more=int(chr(int(list1[len(list1)-1][56:64],2)))  #得到补充位数目
    strtemp1=‘‘.join(list1)
    strtemp2=strtemp1[0:(len(strtemp1)-8*more)]  #去掉补充位
    for i in range(0,len(strtemp2)/8,2):
        if int(strtemp2[i*8:(i+1)*8],2)==0:  #如果此八位为0,则说明后面的一个字节为ascii编码
            string+=chr(int(strtemp2[(i+1)*8:(i+2)*8],2))
        else:       #如果此八位不为0,则说明该字节与后一个为unicode编码
            string+=unichr(int(strtemp2[i*8:(i+2)*8],2))
    return string

  DES.py

# -*- coding: utf-8 -*-
import time
import base64
import os

m=0
C0=‘‘
D0=‘‘
L0=‘‘
R0=‘‘
cipher=‘‘
outtext=‘‘
k=0

substitute1=[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,
             63,55,47,39,31,23,15,
             7 ,62,54,46,38,30,22,
             14, 6,61,53,45,37,29,
             21,13, 5,28,20,12, 4]

substitute2=[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]

shift=[1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1]

KEY=[ dict() for i in range(16)]

sbox= [
        [
        0xe,0x4,0xd,0x1,0x2,0xf,0xb,0x8,0x3,0xa,0x6,0xc,0x5,0x9,0x0,0x7,
        0x0,0xf,0x7,0x4,0xe,0x2,0xd,0x1,0xa,0x6,0xc,0xb,0x9,0x5,0x3,0x8,
        0x4,0x1,0xe,0x8,0xd,0x6,0x2,0xb,0xf,0xc,0x9,0x7,0x3,0xa,0x5,0x0,
        0xf,0xc,0x8,0x2,0x4,0x9,0x1,0x7,0x5,0xb,0x3,0xe,0xa,0x0,0x6,0xd,
        ],
        [
        0xf,0x1,0x8,0xe,0x6,0xb,0x3,0x4,0x9,0x7,0x2,0xd,0xc,0x0,0x5,0xa,
        0x3,0xd,0x4,0x7,0xf,0x2,0x8,0xe,0xc,0x0,0x1,0xa,0x6,0x9,0xb,0x5,
        0x0,0xe,0x7,0xb,0xa,0x4,0xd,0x1,0x5,0x8,0xc,0x6,0x9,0x3,0x2,0xf,
        0xd,0x8,0xa,0x1,0x3,0xf,0x4,0x2,0xb,0x6,0x7,0xc,0x0,0x5,0xe,0x9,
        ],
        [
        0xa,0x0,0x9,0xe,0x6,0x3,0xf,0x5,0x1,0xd,0xc,0x7,0xb,0x4,0x2,0x8,
        0xd,0x7,0x0,0x9,0x3,0x4,0x6,0xa,0x2,0x8,0x5,0xe,0xc,0xb,0xf,0x1,
        0xd,0x6,0x4,0x9,0x8,0xf,0x3,0x0,0xb,0x1,0x2,0xc,0x5,0xa,0xe,0x7,
        0x1,0xa,0xd,0x0,0x6,0x9,0x8,0x7,0x4,0xf,0xe,0x3,0xb,0x5,0x2,0xc,
        ],
        [
        0x7,0xd,0xe,0x3,0x0,0x6,0x9,0xa,0x1,0x2,0x8,0x5,0xb,0xc,0x4,0xf,
        0xd,0x8,0xb,0x5,0x6,0xf,0x0,0x3,0x4,0x7,0x2,0xc,0x1,0xa,0xe,0x9,
        0xa,0x6,0x9,0x0,0xc,0xb,0x7,0xd,0xf,0x1,0x3,0xe,0x5,0x2,0x8,0x4,
        0x3,0xf,0x0,0x6,0xa,0x1,0xd,0x8,0x9,0x4,0x5,0xb,0xc,0x7,0x2,0xe,
        ],
        [
        0x2,0xc,0x4,0x1,0x7,0xa,0xb,0x6,0x8,0x5,0x3,0xf,0xd,0x0,0xe,0x9,
        0xe,0xb,0x2,0xc,0x4,0x7,0xd,0x1,0x5,0x0,0xf,0xa,0x3,0x9,0x8,0x6,
        0x4,0x2,0x1,0xb,0xa,0xd,0x7,0x8,0xf,0x9,0xc,0x5,0x6,0x3,0x0,0xe,
        0xb,0x8,0xc,0x7,0x1,0xe,0x2,0xd,0x6,0xf,0x0,0x9,0xa,0x4,0x5,0x3,
        ],
        [
        0xc,0x1,0xa,0xf,0x9,0x2,0x6,0x8,0x0,0xd,0x3,0x4,0xe,0x7,0x5,0xb,
        0xa,0xf,0x4,0x2,0x7,0xc,0x9,0x5,0x6,0x1,0xd,0xe,0x0,0xb,0x3,0x8,
        0x9,0xe,0xf,0x5,0x2,0x8,0xc,0x3,0x7,0x0,0x4,0xa,0x1,0xd,0xb,0x6,
        0x4,0x3,0x2,0xc,0x9,0x5,0xf,0xa,0xb,0xe,0x1,0x7,0x6,0x0,0x8,0xd,
        ],
        [
        0x4,0xb,0x2,0xe,0xf,0x0,0x8,0xd,0x3,0xc,0x9,0x7,0x5,0xa,0x6,0x1,
        0xd,0x0,0xb,0x7,0x4,0x9,0x1,0xa,0xe,0x3,0x5,0xc,0x2,0xf,0x8,0x6,
        0x1,0x4,0xb,0xd,0xc,0x3,0x7,0xe,0xa,0xf,0x6,0x8,0x0,0x5,0x9,0x2,
        0x6,0xb,0xd,0x8,0x1,0x4,0xa,0x7,0x9,0x5,0x0,0xf,0xe,0x2,0x3,0xc,
        ],
        [
        0xd,0x2,0x8,0x4,0x6,0xf,0xb,0x1,0xa,0x9,0x3,0xe,0x5,0x0,0xc,0x7,
        0x1,0xf,0xd,0x8,0xa,0x3,0x7,0x4,0xc,0x5,0x6,0xb,0x0,0xe,0x9,0x2,
        0x7,0xb,0x4,0x1,0x9,0xc,0xe,0x2,0x0,0x6,0xa,0xd,0xf,0x3,0x5,0x8,
        0x2,0x1,0xe,0x7,0x4,0xa,0x8,0xd,0xf,0xc,0x9,0x0,0x3,0x5,0x6,0xb,
        ]
    ]

substituteip= [
        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]

selectoperate=[
        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]

substituteP=[
        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]

resubstituteip=[
        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]
def before():
    global KEY,m,C0,D0,L0,R0,cipher,outtext,k
    KEY=[ dict() for i in range(16)]
    m=0
    C0=‘‘
    D0=‘‘
    L0=‘‘
    R0=‘‘
    cipher=‘‘
    outtext=‘‘
    k=0

def handleraw(string):
    a=‘‘
    for i in string:
        a+=bin(ord(i)).replace(‘0b‘,‘‘).zfill(8)
    return a

def shiftleft(string,x):    #循环左移
    return string[-(len(string)-x):]+string[:x]

def encodepassword1(x):     #秘钥置换选择
    global C0
    global D0
    for i in range(0,28):
        C0+=x[substitute1[i]-1]
    for j in range(28,56):
        D0+=x[substitute1[j]-1]


def encodepassword2():  #秘钥处理主流程
    global k,C0,D0
    t=‘‘
    if(k!=16):
        C0=shiftleft(C0,shift[k])
        D0=shiftleft(D0,shift[k])
        s=C0+D0
        for i in substitute2:
            t+=s[i-1]
        KEY[k]=t
        k+=1
        encodepassword2()

def substituteIP(string):  #初始置换IP
    global L0,R0
    a=‘‘
    for i in substituteip:
        a+=string[i-1]
    L0=a[:32]
    R0=a[-32:]

def sboxoperate():   #S盒操作
    mid=‘‘
    for i in selectoperate:
        mid+=R0[i-1]
    mid=str(bin(int(mid,2)^int(KEY[m-1],2)).replace(‘0b‘,‘‘).zfill(48))
    outraw=‘‘
    for n in range(8):
        a=int(mid[6*n]+mid[6*n+5],2)
        b=int(mid[(6*n+1):(6*n+5)],2)
        outraw+=str(bin(int(str(sbox[n][a*16+b]),10)).replace(‘0b‘,‘‘).zfill(4))
    out=‘‘
    for i in substituteP:
        out+=outraw[i-1]
    return out

def encodemain():       #加密主流程
    global m,L0,R0,cipher
    m+=1
    a=L0
    L0=R0
    R0=str(bin(int(sboxoperate(),2)^int(a,2)).replace(‘0b‘,‘‘).zfill(32))
    if(m!=16):
        encodemain()
    else:
        b=R0+L0
        for i in resubstituteip:
            cipher+=b[i-1]

def decodecircle():     #解密主流程
    global L0,R0,outtext,m
    a=R0
    R0=L0
    L0=str(bin(int(sboxoperate(),2)^int(a,2)).replace(‘0b‘,‘‘).zfill(32))
    m-=1
    if(m!=0):
        decodecircle()
    else:
        d=L0+R0
        decodetext=[0 for i in range(64)]
        for i in range(64):
            decodetext[substituteip[i]-1]=d[i]
        outtext=‘‘.join(decodetext)

def decoderesubstituteip(string):       #逆置换IP
    global R0,L0,m
    m=16
    a=[0 for i in range(64)]
    for i in range(64):
        a[resubstituteip[i]-1]=string[i]
    a=‘‘.join(a)
    R0=a[:32]
    L0=a[-32:]

def desencode(password,text):   #加密函数
    before()
    encodepassword1(password)
    encodepassword2()
    substituteIP(text)
    encodemain()
    return cipher

def desdecode(password,encodetext): #解密函数
    before()
    encodepassword1(password)
    encodepassword2()
    decoderesubstituteip(encodetext)
    decodecircle()
    return outtext

if __name__==‘__main__‘:
    e=raw_input(‘This is a DES encrypt and decrypt function\n press 1 to encrypt, 2 to decrypt:‘)
    password=raw_input(‘please input the key:‘)
    encodepassword1(password)
    encodepassword2()
    print ‘the KEY is:\n‘,KEY
    if(e==‘1‘):
        text=raw_input(‘please input the text:‘)
        substituteIP(text)
        encodemain()
        print ‘the cipher is:‘,cipher
    if(e==‘2‘):
        ciphertext=raw_input(‘please input the cipher:‘)
        decoderesubstituteip(ciphertext)
        decodecircle()
        print ‘the decodetext is:‘,outtext
    os.system("pause")

  setup.py

import py2exe
from distutils.core import setup

‘‘‘setup(windows=["mainfunc.py"])‘‘‘
setup(
windows = [{"script":"mainfunc.py", "icon_resources": [(1, "lock.ico")]} ]
)

  

 

Python实现DES加密算法的文本加密器