Rating:
Hi All, Challenge description is like below:
"
Title: CCCCC
CCCCC CCCCC CCCCC CCCCC CCCCC CCCCC CCCCC CCCCC CCCCC CCCCC CCCCC CCCCC
CCCCC CCCCC CCCCC
Author: hofill "
Challenge contains a file — ccccc.txt
" Content of the ccccc.txt file:
5c4c4c6c4c3c4c3c5c4c4c6c7cbc6c3c7c3c6c8c6cfc7c5c7c4c5cfc6c3c6cfc7c5c7c4c5cfc6c3c7c4c3c0c5cfc6c3c6cdc7c9c5cfc6c3c6c2c3c0c7c9c5cfc6c3c3c4c6cec6c4c5cfc6c3c6cdc7c9c5cfc6c3c6c4c6cfc6c7c5cfc6c3c6c1c6cec6c4c5cfc6c3c6cdc7c9c5cfc6c3c6c3c3c4c3c7c7cdc0ca "
That’s all. What are you doing now? What are the steps?
Category: [Crypto](https://en.wikipedia.org/wiki/Cryptography).
Quick note — if you want to solve it yourself, give yourself some time now — later it will be too late, because you will already see the solution; that means no such fun:P
I wanted to write about this, because I have a pretty nice tip for you: if you’re tired, get a rest for a while:D I will explain it little bit later.
Look, what do you associate ‘C’ with and the number/s? For example ‘X’ in [Roman numerals](https://en.wikipedia.org/wiki/Roman_numerals) means ‘10’. ‘C’ means ‘100’, etc. Is it useful? Maybe. Or maybe not. How can we know at start here?
It don’t have to be in Roman numerals.
Any patterns?
Initial analysis, source: TFC CTF 2024
Looks like that file named ‘ccccc.txt’ is just a long string.
Referring to my previous ‘[lifehack](https://en.wikipedia.org/wiki/Life_hack)’ — I solved harder challenges there (I focused on this a bit later), and I was a little bit confused at that moment.
In this case [CyberChef](https://gchq.github.io/CyberChef/) (‘Magic’ and so on) failed, [dCode](https://www.dcode.fr/) also. Many other approaches — too. No result.
But… I decided to take a short break, making some completely different activities — and… I came back with some idea!
Great idea!
What if it can be easier as you think? Don’t overthink at this case!
I decided to paste this ‘long string’ in one of my fav code’s editor and remove (cut out) all these ‘C’ letters.
Result:
5446434354467b6373686f75745f636f75745f6374305f636d795f636230795f63346e645f636d795f63646f675f63616e645f636d795f636334377d0a
There was definitely too much ‘C’. Now, looks better. I bet, you know the next steps.
Flag — solution, source: CyberChef & TFC CTF 2024
Flag: **TFCCTF{cshout_cout_ct0_cmy_cb0y_c4nd_cmy_cdog_cand_cmy_cc47}**
I hope you enjoy!
