Python/ciphers/rot13.py
Christian Clauss b1377f0e57
autoblack: actions/checkout@v1 # Use v1, NOT v2 (#1796)
* autoblack: actions/checkout@v1  # Use v1, NOT v2

* fixup! Format Python code with psf/black push

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
2020-03-13 09:23:38 +01:00

38 lines
826 B
Python

def dencrypt(s: str, n: int = 13):
"""
https://en.wikipedia.org/wiki/ROT13
>>> msg = "My secret bank account number is 173-52946 so don't tell anyone!!"
>>> s = dencrypt(msg)
>>> s
"Zl frperg onax nppbhag ahzore vf 173-52946 fb qba'g gryy nalbar!!"
>>> dencrypt(s) == msg
True
"""
out = ""
for c in s:
if "A" <= c <= "Z":
out += chr(ord("A") + (ord(c) - ord("A") + n) % 26)
elif "a" <= c <= "z":
out += chr(ord("a") + (ord(c) - ord("a") + n) % 26)
else:
out += c
return out
def main():
s0 = input("Enter message: ")
s1 = dencrypt(s0, 13)
print("Encryption:", s1)
s2 = dencrypt(s1, 13)
print("Decryption: ", s2)
if __name__ == "__main__":
import doctest
doctest.testmod()
main()