Python实现维吉尼亚密码加解密与密钥破解

def VigenereEncrypto(message, key):
 msLen = len(message)
 keyLen = len(key)
 message = message.upper()
 key = key.upper()
 raw = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"# 明文空间
 # 定义加密后的字符串
 ciphertext = ""
 # 开始加密
 for i in range(0, msLen):
  # 轮询key的字符
  j = i % keyLen
  # 判断字符是否为英文字符，不是则直接向后面追加且继续
  if message[i] not in raw:
   ciphertext += message[i]
   continue
  encodechr = chr((ord(message[i]) - ord("A") + ord(key[j]) - ord("A")) % 26 + ord("A"))
  # 追加字符
  ciphertext += encodechr
 # 返回加密后的字符串
 return ciphertext
if __name__ == "__main__":
 message = "Hello, World!"
 key = "key"
 text = VigenereEncrypto(message, key)
 print(text)
def VigenereDecrypto(ciphertext, key):
 msLen = len(ciphertext)
 keyLen = len(key)
 key = key.upper()
 raw = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"# 密文空间
 plaintext = ""
 for i in range(0, msLen):# 开始解密
  # 轮询key的字符
  j = i % keyLen
  # 判断字符是否为英文字符，不是则直接向后面追加且继续
  if ciphertext[i] not in raw:
   plaintext += ciphertext[i]
   continue
  decodechr = chr((ord(ciphertext[i]) - ord("A") - ord(key[j]) - ord("A")) % 26 + ord("A"))
  # 追加字符
  plaintext += decodechr
 # 返回加密后的字符串
 return plaintext
if __name__=="__main__":
 ciphertext = "RIJVS, AMBPB!"
 key = "key"
 text = VigenereDecrypto(ciphertext, key)
 print(text)
import VigenereDecrypto
import VigenereEncrypto
def main():
 info = '''==========********=========='''# 开始加密
 print(info, "\n------维吉尼亚加密算法------")
 print(info)
 # 读取测试文本文档
 message = open("test.txt","r+").read()
 print("读取测试文本文档:test.txt")
 print("开始加密！")
 # 输入key
 key = input("请输入密钥：")
 # 进入加密算法
 CipherText = VigenereEncrypto.VigenereEncrypto(message, key)
 # 写入密文文本文档
 C = open("CipherText.txt", "w+")
 C.write(CipherText)
 C.close()
 print("加密后得到的密文是: \n" + CipherText)
 # 开始解密
 print(info, "\n------维吉尼亚解密算法------")
 print(info)
 # 读取加密文本文档
 print("读取密文文本文档：CipherText.txt")
 Ciphertext = open("CipherText.txt", "r+").read()
 # 进入解密算法
 print("开始解密！")
 Plaintext = VigenereDecrypto.VigenereDecrypto(Ciphertext, key)
 P = open("PlainText.txt", "w+")
 # 写入解密文本文档
 P.write(Plaintext)
 P.close()
 print("解密后得到的明文是 : \n" + Plaintext)
if __name__=="__main__":
 main()

def main():
 fo=open("cipher.txt","r")
 s=fo.read()
 s=str(s)
 fo.close()
 ic=0
 max_num=len(s)//26
 # while ic<0.06:
 #def fenzu():
 #分组
 aves=[0]*max_num
 for i in range(1,max_num):
  count = 0
  zicuan=[]
  for t in range (i):
   fz=s[t:len(s):i]
   zicuan+=[fz]
   count+=1
   #print(count,'韩庚韩庚韩庚',zicuan)
  for js in range (i):
   zicuan[js]=zicuan[js].upper()
  ics=[0]*count
  #统计每个分组的IC值
  for r in range(count):
   ics[r]=tongjicisu(zicuan[r])
  ave =sum(ics)/count
  print('第{}次分片的IC值是{}'.format(i,ave))
  aves[i-1]=ave
 #找到最可能的密钥分组
 key_index=1
 max = 1
 for i in range(max_num):
  max1=abs(aves[i]-0.065)
  if max1<max:
   max=max1
   key_index=i+1
 print('key_length',key_index)
 key = [None]*key_index
 #得到密钥长度后从新按密钥长度分片计算
 zicuan2 = []
 for t in range(key_index):
  fz = s[t:len(s):key_index]
  zicuan2 += [fz]
 for i in range(key_index):
  key[i]=decode(zicuan2[i])
 print(key)
 di = {}.fromkeys(key)
 key=di.keys()
 keys=""
 for i in key:
  keys+=i
 
 print(keys,"密钥")
 mc = VigenereDecrypto(s,keys)
 print(mc,'ecewew')
 
# 统计次数IC值
def tongjicisu(s):
 tongjicisu = [0] * 26
 zff = ""
 ic=-0
 for t in s:
  if 65 <= ord(t) <= 90:
   zff += t
 for cisu in zff:
  tongjicisu[ord(cisu) - 65] += 1
 for i in range (len(tongjicisu)):
  xic=tongjicisu[i]*(tongjicisu[i]-1)/len(zff)/(len(zff)-1)
  ic+=xic
 return ic
 
def decode(s):
 nicos=[0]*26
 for i in range(26):
  nicos[i]=tongjinichonghe(i,s)
 list1=sorted(nicos)
 num = nicos.index(list1[-1])
 ch = chr(num+65)
 #print(ch)
 return ch
#计算拟重合指数
def tongjinichonghe(key,s):
 sniic=0
 p = [0.08167, 0.01492, 0.02782, 0.04253, 0.12702, 0.02228, 0.02015, 0.06094, 0.06966, 0.00153, 0.00772, 0.04025,
   0.02406, 0.06749, 0.07507, 0.01929, 0.00095, 0.05987, 0.06327, 0.09056, 0.02758, 0.00978, 0.02360, 0.00150,
   0.01974, 0.00074]
 tongjinichonghe = [0] * 26
 zff = ""
 #ic=-0
 #转换为只有大写字母的字符串
 for t in s:
  if 65 <= ord(t) <= 90:
   zff += t
 #统计每个字母出现的次数
 for cisu in zff:
  tongjinichonghe[ord(cisu) - 65] += 1
 #求出每个凯撒加密的解密，根据拟重合指数找到正确的密钥
 list0=tongjinichonghe
 list1=[0]*26
 for i in range (26):
  list1[i]=list0[(i+key)%26]
 tongjinichonghe=list1
 for i in range (len(tongjinichonghe)):
  niic=tongjinichonghe[i]/len(tongjinichonghe)*p[i]
  sniic+=niic
 return sniic
 
def VigenereDecrypto(ciphertext, key):
 msLen = len(ciphertext)
 keyLen = len(key)
 key = key.upper()
 raw = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"# 密文空间
 plaintext = ""
 for i in range(0, msLen):# 开始解密
  # 轮询key的字符
  j = i % keyLen
  # 判断字符是否为英文字符，不是则直接向后面追加且继续
  if ciphertext[i] not in raw:
   plaintext += ciphertext[i]
   continue
  decodechr = chr((ord(ciphertext[i]) - ord("A") - ord(key[j]) - ord("A")) % 26 + ord("A"))
  # 追加字符
  plaintext += decodechr
 # 返回加密后的字符串
 return plaintext
 
if __name__ == '__main__':
 main()