picoCTF - interencdec

Posted on Jan 26, 2026
  • URL: https://play.picoctf.org/practice/challenge/418
  • Title: interencdec
  • Tags: Easy, Cryptography, picoCTF 2024, base64, browser_webshell_solvable
  • Author: NGIRIMANA Schadrack
  • Started: 20 July 2025
  • Solved: 20 July 2025
  • Description: Can you get the real meaning from this file. Download the file here.

After downloading the file, I displayed the content

strikingsoul@ramones:~/Downloads$ cat enc_flag 
YidkM0JxZGtwQlRYdHFhR3g2YUhsZmF6TnFlVGwzWVROclgya3lNRFJvYTJvMmZRPT0nCg==

After a base64 decode, there flag is still encrypted

strikingsoul@ramones:~/Downloads$ cat enc_flag | base64 --decode
b'd3BqdkpBTXtqaGx6aHlfazNqeTl3YTNrX2kyMDRoa2o2fQ=='

d3BqdkpBTXtqaGx6aHlfazNqeTl3YTNrX2kyMDRoa2o2fQ==

After decoded once again, the message is still gibberish

strikingsoul@ramones:~/Downloads$ echo d3BqdkpBTXtqaGx6aHlfazNqeTl3YTNrX2kyMDRoa2o2fQ== | base64 --decode
wpjvJAM{jhlzhy_k3jy9wa3k_i204hkj6}

Okay, I thought it was a caesar cipher

alt text

The final flag is picoCTF{caesar_d3cr9pt3d_b204adc6}