Didactic Scrambled Egg Cipher Pre-Warmup

[Meelo]

Well, I've been working on this challenge for a few days, but I'm wondering if there's a faster way to get the key than to go through all possibilities (256*256*256*256 is a bit too much for my computer to do in a reasonable amount of time). I think from some tests I did that I'm properly undoing all the other steps in the encryption, but I won't say how because that would give some of the challenge away. I mean, there must be some bits in the final answer that can be prematurely calculated with a single byte of the key, and you could probably somehow optimize on that.

[Zeta]

Brute force worked for me. It doesn't take forever even on a slow machine with an interpreted language. You only have to detect failures fast.

[Meelo]

Failures as in keys that are obviously wrong?

Yeah... I'll try that.

[zael]

I'm wondering if there's actually a way to reverse the algorithm. The final AND mask which truncates it to 3 bytes is obviously lossy.. but there's many people smarter than me, so I do wonder if it's possible to reverse? I'd be fascinated at the way to reverse it, yet that would be spoiling the solution.

[Kami]

Well, if you don't just reverse the algorythm for decryption, but understand what it does - visualizing the bits affected by the steps helps - you'll see that there is a simple way not to have to test all 256^4 keys.

[Aiyion.Prime]

One cannot enter a solution for this one at the moment, right?
I think I found the text and am pretty sure of phase two as well.