Answer: Secret Code #170

The secret message says:

HAPPY CODING

The shift was 7.

The secret note decoded: HAPPY CODING
The note, decoded.

Letter by letter

Secret letterFHJKNOPUVW
Real letterYACDGHINOP

Decode it with Python

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

secret = "OHWWF JVKPUN"
shift = 7
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:

HAPPY CODING

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.