Re: [PATCH 0/6] Constant Time Memory Comparisons Are Important

On Sun, Jun 11, 2017 at 1:13 AM, Kalle Valo [off-list ref] wrote:

"Jason A. Donenfeld" [off-list ref] writes:

quoted

Whenever you're comparing two MACs, it's important to do this using
crypto_memneq instead of memcmp. With memcmp, you leak timing information,
which could then be used to iteratively forge a MAC.

Do you have any pointers where I could learn more about this?

While not using C specifically, this talks about the problem generally:
https://www.chosenplaintext.ca/articles/beginners-guide-constant-time-cryptography.html

-Kees

-- 
Kees Cook
Pixel Security