> The attacker can do timing on his side Yes, I mentioned that in my comment: > We also need to prevent attackers from being able to time their code's executi

> The attacker can do timing on his side Yes, I mentioned that in my comment: > We also need to prevent attackers from being able to time their code's execution remotely. I don't think it's impossible to mitigate. First, not all use cases actually involve the attacker being able to directly invoke and then measure the timing of their code. Imagine, for example, that I'm using attacker-provided code to apply some image manipulation to a photo on my phone, then I post the photo online. The attacker doesn't have any way to know how long their code took to execute, and I can be confident that they haven't exfiltrated side channels through the image via steganography because their code was deterministic so couldn't have incorporated those side channels into its output. Second, I don't think the space of timer noise techniques has been adequately explored. Timer noise is one of the main defenses browsers have deployed against spectre, and pragmatically speaking it has been reasonable effective. Yes, in theory there are lots of statistical techniques an attacker might use to get around it, but it certainly increases the cost of attack. We need to figure out how to push the cost of an attack out-of-reach, even if we can't make it completely impossible.