6 minutes ago, Washi said:

@Sawyer555

Automation is your best friend in this challenge.

It uses 20 bytes as input, I guess bruteforce isn't an option. Do I have to let the binary work for me somehow? I was going to try and understand the encryption somehow but I believe this is not the right way.

On 10/12/2025 at 8:35 PM, Washi said:

A debugger's callstack is your best friend :)

You probably want to revisit that reasoning

Then we must conclude things that come in are not the right input parameters...

The same approach should apply for the entire binary. Follow the breadcrumbs, they are sneaky with some of the encryption throughout the protocol...

Are they really 4 exact copies of the binary?

@Washi no, it has difference but I don't know what its effect is? What should I do next, please?

@Sawyer555

On 10/13/2025 at 12:40 PM, Sawyer555 said:

Do I have to let the binary work for me somehow?

The binary itself is probably going to be too inefficient for you to do anything interesting at runtime, other than validating some individual tests. As for bruteforce, flare-on typically requires no bruteforce for any challenge, let alone bruteforcing 0x20 bytes which definitely won't finish before the end of the universe :^).

@pypy

@Washi no, it has difference but I don't know what its effect is? What should I do next, please?

Pay close attention to how it differs. Is it deterministic?

Any hints for ch6?

I have the decompiled Python code and the contracts, but I can't derive the keys

Edited Tuesday at 10:11 PM2 days by eric_cartman

7 hours ago, Washi said:

@Sawyer555

The binary itself is probably going to be too inefficient for you to do anything interesting at runtime, other than validating some individual tests. As for bruteforce, flare-on typically requires no bruteforce for any challenge, let alone bruteforcing 0x20 bytes which definitely won't finish before the end of the universe :^).

@pypy

@Washi no, it has difference but I don't know what its effect is? What should I do next, please?

Pay close attention to how it differs. Is it deterministic?

@Washi thank you very much, I have solved it!

On 10/14/2025 at 8:31 PM, Washi said:

@Sawyer555

The binary itself is probably going to be too inefficient for you to do anything interesting at runtime, other than validating some individual tests. As for bruteforce, flare-on typically requires no bruteforce for any challenge, let alone bruteforcing 0x20 bytes which definitely won't finish before the end of the universe :^).

I have progress a lot, but I'm really struggling to figure out what happens between the "f" functions and the memcmp. It's some sort of matrix manipulation but just so damn complicated. How am I supposed to reverse that?

@Sawyer555

Try to identify the high level semantics that the code implements, as opposed to zooming in too much on the individual operations. After that, then it is pen and paper time :)

On 10/12/2025 at 9:34 AM, pypy said:

hi, can you give some hints for CH4, please? I've patched the M byte to make it run and I see it clones 4 copies. What should I do next?

Try playing with filename... It change something?