Bit by Bit
I solve this challenge with some misinterpretations, but in the end I got the correct overall theme: Legendre Symbols. I guess I got lucky with the local testing and derive the correct relation. The challenge, as suggested by the category, is about the ElGamal construction. More information can be found at this Wikipedia link, or any textbook in cryptography should cover this. The very first observation is that each iteration of the while loop is operating 1 bit of the flag at a time, starting from the last bit of the flag....