A classic:
'''Caesar_Cipher1.py
Caesar Cipher encryption/decryption
using Python's double-ended queue rotation
'''
import string
from collections import deque
def caesar_cipher(text, shift, decode=False):
# change from encode to decode if decode=True
if decode:
shift = -shift
alpha = string.ascii_uppercase + string.ascii_lowercase
dq = deque(alpha)
# shift/rotate the alphabet (dq in place)
dq.rotate(shift)
crypted = ""
for c in text:
if c in alpha:
# get the letter's index in alpha and apply to dq
index_alpha = alpha.index(c)
crypted += dq[index_alpha]
else:
crypted += c
return crypted
# testing ...
# shift key should be less than 26
shift = 11
# test, change letters not other characters
text = "The quick brown fox jumped over the lazy dogs ..123!"
print(text)
encoded = caesar_cipher(text, shift)
print(encoded)
print(caesar_cipher(encoded, shift, decode=True))
''' result ...
The quick brown fox jumped over the lazy dogs ..123!
IWT fjXRZ Qgdlc Udm YjbeTS dkTg iWT aPon SdVh ..123!
The quick brown fox jumped over the lazy dogs ..123!
'''
