• URL: https://play.picoctf.org/practice/challenge/68
• Title: RED
• Tags: Easy, Cryptography, picoCTF 2019,
• Author: Danny
• Started: 20 July 2025
• Solved: 20 July 2025
• Description: The numbers… what do they mean? numbers.png

Opening numbers.png, it showed this

I noticed the curly brackets and the 4 starting numbers: 16, 9, 3, 15. If you align it with alphabet order. I could just use pen and paper or even code about it but in this case I used CyberChef, the algorithm is called A1Z16

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• 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

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