Vigenere Cipher

A vigenere Cipher uses a different strategy to create the key stream. The key stream is repetition of initial key stream of length m  where we have  1<=key<=26 .

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Python Source Code :

1. # Vigenere Cipher
2. # codecops.in
3. def VigenereCipher(plainText,keys):
4.     # Vigenere Cipher
5.     plainText=plainText.upper()
   

   plainText=plainText.replace(' ','')
6.     block=len(keys)
7.     sizep=len(plainText)
8.     cipher=[]
9.     for i in range(0,sizep,block):
10.         if i+block<=sizep:
11.             for j in range(i,i+block):
12.                 cipher.append(chr((((ord(plainText[j])-64)+keys[j-i])%26 +64)))
13.         else:
14.             for j in range(i,sizep):
15.                 cipher.append(chr((((ord(plainText[j])-64)+keys[j-i])%26 +64)))
17.     return "".join(cipher)
19. if __name__=='__main__':
20.     pt=raw_input("Plain Text : ")
21.     key=[int(x) for x in raw_input("key Stream : ").split(' ')]
22.     print "Vigenere Cipher"
23.     print VigenereCipher(pt,key)

Output :

Vigenere cipher Output