picoCTF General Skills Guide

Bases

Name: Bases
Description: What does this bDNhcm5fdGgzX3IwcDM1 mean? I think it has something to do with bases.
Author: Sanjay C/Danny T
Tags: Easy, General Skills, picoCTF 2019
Challenge from: picoCTF 2019
Hints:
1. Submit your answer in our flag format. For example, if your answer was 'hello', you would submit 'picoCTF{hello}' as the flag.

Theory

According to the description, to get the flag we have to convert that weird string of text that looks oddly like Base64, back to text and submit it. I think it's Base64 because even if it doesn't have the usual equal sign at the end (= or ==) it does have the same set of letters both upper and lower case, and the structure just looks really like it would on a Base64 string. So let's go decode it in Base64 to see if it's really that.

Solution

Let's check by decoding from Base64:

BASE64 DECODE (Base64Decode.com)

INPUT: bDNhcm5fdGgzX3IwcDM1

OUTPUT: l3arn_th3_r0p35

Great, it was really Base64, now let's put it in the usual pico flag format and submit it:

Submit Flag: picoCTF{l3arn_th3_r0p35}

Check: Correct!

There we go! That's the flag.

I rated this level as "good"! :3