Python/ciphers/vigenere_cipher.py

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Python
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from __future__ import print_function
2016-08-11 12:44:46 +00:00
LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
def main():
message = input('Enter message: ')
key = input('Enter key [alphanumeric]: ')
mode = input('Encrypt/Decrypt [e/d]: ')
if mode.lower().startswith('e'):
mode = 'encrypt'
translated = encryptMessage(key, message)
elif mode.lower().startswith('d'):
mode = 'decrypt'
translated = decryptMessage(key, message)
print('\n%sed message:' % mode.title())
print(translated)
def encryptMessage(key, message):
'''
>>> encryptMessage('HDarji', 'This is Harshil Darji from Dharmaj.')
'Akij ra Odrjqqs Gaisq muod Mphumrs.'
'''
return translateMessage(key, message, 'encrypt')
def decryptMessage(key, message):
'''
>>> decryptMessage('HDarji', 'Akij ra Odrjqqs Gaisq muod Mphumrs.')
'This is Harshil Darji from Dharmaj.'
'''
return translateMessage(key, message, 'decrypt')
def translateMessage(key, message, mode):
translated = []
keyIndex = 0
key = key.upper()
for symbol in message:
num = LETTERS.find(symbol.upper())
if num != -1:
if mode == 'encrypt':
num += LETTERS.find(key[keyIndex])
elif mode == 'decrypt':
num -= LETTERS.find(key[keyIndex])
num %= len(LETTERS)
if symbol.isupper():
translated.append(LETTERS[num])
elif symbol.islower():
translated.append(LETTERS[num].lower())
keyIndex += 1
if keyIndex == len(key):
keyIndex = 0
else:
translated.append(symbol)
return ''.join(translated)
if __name__ == '__main__':
main()