Hotflip is a white-box attack, but there is no gradient calculation in the code; instead, it uses brute-force search.

[20090409]

Hello, I have reviewed the implementation of the hotflip attack algorithm in your attacker. According to my research on the literature, this is an attack algorithm based on white-box gradients. However, there are no steps related to gradient calculation in the code. Could you please explain why? thank you