Hard Live

Linear-feedback. Shift. Register.

90 points

13 Solves



Community Rating: 5.00 / 5


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I have just implemented a super-cool PRNG!

I've used every next generated by it number to XOR every next character in my super-secret message with.

Are you able to retrieve it?

Btw. Biggest possibly generated number by my PRNG is 255.

Psst. The retrieved message would be your flag!

As always, starting with: CTFlearn{...

I'm giving you the PRNG scheme with a brief description (description.png) and a "secretMessage.hex" file with every byte being the corresponding message char inside PRNG.zip file.

First 10 Solvers

Rank Username
1 uynguyen
2 Gilad ctflearn++ badge
3 ebouteillon
4 SunTzu
5 momo1
Rank Username
6 spintronix
7 zharfanf
8 3cd54
9 Rivit
10 impulse


    • michaelmichael


      Wiki title. Once you fully understand the idea of the N mask, you can solve by trial and error with python string and xor skills. You should also be fluid in representing ascii strings in binary format to see what is happening with patterns...

    • Ichild

      Protected 1

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    • uynguyen


      The nice one! We have to do many steps by hand to find the seed key

      • Wolfowy


        Thanks! It depends on an approach ;)