# Author: OMKAR PATHAK

# This program illustrates a simple example for encrypting/ decrypting your text

LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

LETTERS = LETTERS.lower()

def encrypt(message, key):

''' This function lets you to encrypt your message based on a key '''

encrypted = ''

for chars in message:

if chars in LETTERS:

num = LETTERS.find(chars)

num += key

encrypted += LETTERS[num]

return encrypted

def decrypt(message, key):

''' This function lets you to decrypt your message based on a key '''

decrypted = ''

for chars in message:

if chars in LETTERS:

num = LETTERS.find(chars)

num -= key

decrypted += LETTERS[num]

return decrypted

def main():

message = str(input('Enter your message: '))

key = int(input('Enter you key [1 - 26]: '))

choice = input('Encrypt or Decrypt? [E/D]: ')

if choice.lower().startswith('e'):

print(encrypt(message, key))

else:

print(decrypt(message, key))

if __name__ == '__main__':

main()

# OUTPUT:

# omkarpathak@omkarpathak-Inspiron-3542:~/Documents/GITs/Python-Programs/Programs$ python P40_CipherText.py

# Enter your message: omkar

# Enter you key [1 - 26]: 2

# Encrypt or Decrypt? [E/D]: e

# qomct

#

# omkarpathak@omkarpathak-Inspiron-3542:~/Documents/GITs/Python-Programs/Programs$ python P40_CipherText.py

# Enter your message: qomct

# Enter you key [1 - 26]: 2

# Encrypt or Decrypt? [E/D]: d

# omkar