Answer: Secret Code #168

The secret message says:

PUZZLE PRO

The shift was 13.

The secret note decoded: PUZZLE PRO
The note, decoded.

Letter by letter

Secret letterBCEHMRY
Real letterOPRUZEL

Decode it with Python

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

secret = "CHMMYR CEB"
shift = 13
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:

PUZZLE PRO

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.