Answer: Secret Code #177

The secret message says:

PYTHON

The shift was 22.

The secret note decoded: PYTHON
The note, decoded.

Letter by letter

Secret letterDJKLPU
Real letterHNOPTY

Decode it with Python

This program does the decoding for you. Change the secret and the shift to crack other messages!

secret = "LUPDKJ"
shift = 22
message = ""

for letter in secret:
    if letter.isalpha():
        number = (ord(letter) - ord("A") - shift) % 26
        message = message + chr(number + ord("A"))
    else:
        message = message + letter

print(message)

When you run it, it prints:

PYTHON

Did you know? Shift codes are very old. A Roman writer called Suetonius said that Julius Caesar wrote secret letters by shifting the alphabet by three. That’s why it’s often called the Caesar cipher.