HiddenCipher

This challenge provides a hiddencipher binary along with a flag.txt file containing a fake flag, as we are currently running it locally. When we execute the program, it returns an encrypted flag. This strongly suggests the use of an XOR cipher. Since we have both the plaintext and the ciphertext, we can recover the key by XORing the two values together.

Using cyberchef, we found that the key is S3cr3t, by running a xor with that key and the ciphertext of the real challenge, we get the flag !