Crypto: Caesar Shift

Recover a plaintext encrypted with a Caesar cipher and extract the flag.

Nov 6, 2025

Crypto: Caesar Shift

  • Category: Cryptography
  • Difficulty: Easy
  • Goal: Decrypt the given ciphertext and retrieve the flag.

Scenario

You intercepted a message that appears to be encoded with a simple substitution: a Caesar shift.

GUR SYNAT VF: synt{frperg_cevpr_bs_zngevk}

Task

  • Identify the shift and decode the message.
  • Submit the flag in the form flag{...}.

Hints

  • Caesar shift is a rotation over the alphabet. ROT13 is a popular variant.
  • Try online decoders or write a quick script.

Expected approach

  • Recognize it is ROT13.
  • Decoding yields: THE FLAG IS: flag{secret_price_of_matrix}.

Solution (expand to view)

Show solution

Using ROT13 on the ciphertext:

GUR SYNAT VF: synt{frperg_cevpr_bs_zngevk} -> THE FLAG IS: flag{secret_price_of_matrix}
Forensics: PCAP Stego