Python/ciphers/caesar_cipher.py

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Python
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2016-07-29 07:00:38 +00:00
# The Caesar Cipher Algorithm
message = input("Enter message: ")
key = int(input("Key [1-26]: "))
mode = input("Encrypt or Decrypt [e/d]: ")
if mode.lower().startswith('e'):
mode = "encrypt"
elif mode.lower().startswith('d'):
mode = "decrypt"
LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
translated = ""
message = message.upper()
for symbol in message:
if symbol in LETTERS:
num = LETTERS.find(symbol)
if mode == "encrypt":
num = num + key
elif mode == "decrypt":
num = num - key
if num >= len(LETTERS):
num = num - len(LETTERS)
elif num < 0:
num = num + len(LETTERS)
translated = translated + LETTERS[num]
else:
translated = translated + symbol
if mode == "encrypt":
print("Encryption:", translated)
elif mode == "decrypt":
print("Decryption:", translated)