Hiddencipher2

This challenge provides us a flag.txt and a binary file, that makes us do a mathematical operation, and that outputs the encoded flag value. By looking at the disassembly of the hiddencipher2, we see that the program reads the flag.txt, and use a encode_flag function with two arguments, one being the clear flag string, the other being the result of the math operation we provided.

Looking at the encode_flag function, we see that each char value is being multiplied by the second argument. By doing a small python script, taking each encode characters, dividing it by the value of our input, we find the flag in clear text !

Script :