python实现Virginia无密钥解密

2023-08-25 17:28:05 139

本文实例为大家分享了Virginia无密钥解密的具体代码，供大家参考，具体内容如下

加密

virginia加密是一种多表替换加密方法，通过这种方法，可以有效的解决单表替换中无法应对的字母频度攻击。这种加密方法最重要的就是选取合适的密钥，一旦密钥被公开，保密性也就无从谈起。结合virginia加密原理，给出使用python实现的代码

plainText="whenigotthethemeithoughtofgooglesartificialintelligencealphagothisprogramoverthebestofhumanplayeriwanttoaskwhenscienceandtechnologycontinuetodevelopwehumanbeingswillbewhatpositionweshouldrealizethatthedevelopmentofscienceandtechnologyisirreversibleanditconstituteaprimaryprductiveforcebutmanmustkeeppacewiththetimestoenhancetheablitytocontrol"#密文
alphabet="abcdefghijklmnopqrstuvwxyz"#26个字母
cipherText="";
key="helloworld"#密钥
keyLen=len(key)
plainTextLen=len(plainText)
j=0
foriinrange(0,plainTextLen):
j=i%keyLen
keyNum=alphabet.index(key[j])
plainNum=alphabet.index(plainText[i])
plainTemp=alphabet[(keyNum*plainNum)%26]#密钥对明文作用
cipherText+=plainTemp
print(cipherText)

解密

重点谈谈解密部分。这里的解密主要分为获取密钥长度，根据密钥长度获取密钥，根据密钥获取明文三个部分。

获取密钥长度

使用暴力破解密钥长度的方法，循环遍历可能的密钥长度。每次循环中，记录在这种密钥长度下重复相隔密钥长度密文的次数，从理论上来讲，次数最多的那个密钥长度，最有可能正确。当密文长度足够长时，正确的可能性很高。给出获取密钥长度的python函数代码：

defgetKeyLen(cipherText):#获取密钥长度
keylength=1
maxCount=0
forstepinrange(3,18):#循环密钥长度
count=0
foriinrange(step,len(cipherText)-step):
ifcipherText[i]==cipherText[i+step]:
count+=1
ifcount>maxCount:#每次保存最大次数的密钥长度
maxCount=count
keylength=step
returnkeylength#返回密钥长度

获取密钥

当已经获取密钥长度之后，我们可以通过分组将相同密钥作用下的密文进行分组，在每一组中，都是一个简单的单表替换加密。在这种情况下，我们通过重合指数法破解密钥，给出获取密钥部分的python函数代码：

defgetKey(text,length):#获取密钥
key=[]#定义空白列表用来存密钥
alphaRate=[0.08167,0.01492,0.02782,0.04253,0.12705,0.02228,0.02015,0.06094,0.06996,0.00153,0.00772,0.04025,0.02406,0.06749,0.07507,0.01929,0.0009,0.05987,0.06327,0.09056,0.02758,0.00978,0.02360,0.0015,0.01974,0.00074]
matrix=textToList(text,length)
foriinrange(length):
w=[row[i]forrowinmatrix]#获取每组密文
li=countList(w)
powLi=[]#算乘积
forjinrange(26):
Sum=0.0
forkinrange(26):
Sum+=alphaRate[k]*li[k]
powLi.append(Sum)
li=li[1:]+li[:1]#循环移位
Abs=100
ch=''
forjinrange(len(powLi)):
ifabs(powLi[j]-0.065546)
 破解明文
在已知密钥和明文的基础上，我们很容易就可以得到明文，给出python代码：
defvirginiaCrack(cipherText):#解密函数
length=getKeyLen(cipherText)#得到密钥长度
key=getKey(cipherText,length)#找到密钥
keyStr=''
forkinkey:
keyStr+=k
print('theKeyis:',keyStr)
plainText=''
index=0
forchincipherText:
c=chr((ord(ch)-ord(key[index%length]))%26+97)
plainText+=c
index+=1
returnplainText#返回明文

代码
这是解密部分的全部代码，注意需要自己添加密文文件的位置
defvirginiaCrack(cipherText):#解密函数
length=getKeyLen(cipherText)#得到密钥长度
key=getKey(cipherText,length)#找到密钥
keyStr=''
forkinkey:
keyStr+=k
print('thekey:',keyStr)
plainText=''
index=0
forchincipherText:
c=chr((ord(ch)-ord(key[index%length]))%26+97)
plainText+=c
index+=1
returnplainText
defopenfile(fileName):#读文件
file=open(fileName,'r')
text=file.read()
file.close();
text=text.replace('\n','')
returntext

defgetKeyLen(cipherText):#获取密钥长度
keylength=1
maxCount=0
forstepinrange(3,18):#循环密钥长度
count=0
foriinrange(step,len(cipherText)-step):
ifcipherText[i]==cipherText[i+step]:
count+=1
ifcount>maxCount:
maxCount=count
keylength=step
returnkeylength

defgetKey(text,length):#获取密钥
key=[]#定义空白列表用来存密钥
alphaRate=[0.08167,0.01492,0.02782,0.04253,0.12705,0.02228,0.02015,0.06094,0.06996,0.00153,0.00772,0.04025,0.02406,0.06749,0.07507,0.01929,0.0009,0.05987,0.06327,0.09056,0.02758,0.00978,0.02360,0.0015,0.01974,0.00074]
matrix=textToList(text,length)
foriinrange(length):
w=[row[i]forrowinmatrix]#获取每组密文
li=countList(w)
powLi=[]#算乘积
forjinrange(26):
Sum=0.0
forkinrange(26):
Sum+=alphaRate[k]*li[k]
powLi.append(Sum)
li=li[1:]+li[:1]#循环移位
Abs=100
ch=''
forjinrange(len(powLi)):
ifabs(powLi[j]-0.065546)
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持毛票票。

python实现Virginia无密钥解密

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