Do dai khoa: 6
Khoa       : b'STRIKE'
Ban ro     :
When you XOR a plaintext against a repeating key, the ciphertext still carries the shape of the language underneath it. Every column that lines up with one byte of the key is nothing more than a single byte XOR, and a single byte XOR is trivially broken by trying all two hundred and fifty six possibilities and scoring the result. The only real trick is figuring out how long the key is, and the Hamming distance between blocks hands that to you almost for free. flag{h4mming_distance_unlocks_the_keysize} Keep the text long enough and the statistics will always win in the end, every single time.
