Didactic Feedback Cipher Long 2

[laz0r]

I'm sorry, I don't know why I typed 'tails' when I meant 'adum'... I knew adum made it, and everything! Many apologies for this slight on your challenge-making abilities, tails

[compudemon]

the first 8 bytes is
5499fa99
am i correct in assessing that this translates to the 8 byte number
0x99fa9954 with 99 the most significant
brute force failed when assuming
it was 0x5499fa99
i wanted to know if the fail was my algorithm or just endianness.

[ElleXuzZ]

Hello,

I am a little bit confused with this one.

I did Didactic Feedback Cipher Long and would guess I have to split the crypto-text into 4 byte long numbers, starting with 5499fa99. But when I do so, I end up with a single "80" at the end?

What did I do wrong?

Additionally I would like to know if all of the character-values are below 126 (7e)?

EDIT:
got it myself and solved the challenge, but i also got some mistakes in the final message.
i could only solve it by changing one letter in the code-word (like b instead of a) and i am pretty sure i got the right x
(don't know if this was part of the solution)

[aurquiel]

if i try brute force my program takes to long to guess the 8 bytes 4 from k and another for x, am i doing with the correct point of view?

[Hckr]

There is a better way but the solution can definitely be brute-forced.

[aurquiel]

Well the script that i was able to implement in cipher long 1 taked aorund 689 seconds to decrypt the string, so i added another for cicle for the x variable but imagine something like 689 seconds * 0xFFFFFFFF i was running the new sript for two days, it was impossible to get a fast answer.

I am using two for cilce each one form 0 to 0xFFFFFFFF, it is just simple too many cases.

[Hckr]

You are missing something. Try to get a better understanding of how this cipher works. You should be able to do Didactic Feedback Cipher Long in milliseconds before moving on to the next one.