WARNING!!! THIS CHALLENGE IS HARD (i think)!!!
We have been intercepting the alien communications, and it seems they are using an old, cryptographically insecure hashing function with constraints as a means of encrypting their messages... Using the intercepted data, we have created a small testing program. Using the source code for this program, determine which input string will pass the checks in place.
Author: @captainboggle
Source: crc.c
This is my implementation of yellowsubmarine's solution
Chinese Remainder Theorem over polynomials in GF(2)
CRC is polynomial division with some divisor which returns a remainder. Since this was applied to multiple different remainders, and GF(2) polynomials form what's called a mathematical "ring", properties like factoring, multiplication etc. allow CRT to apply. @yellowsubmarine
I thought this was interesting so I gave a shot at implementing it
Solve the ctf
> python ctf_solve.c
Example solving a known message
> python known_solve.c
Example solving integers instead of text
> python num_solve.py
GF(2) demonstration of extended euclidean algorithm
> python gf2.py