Re: [hash2] Formal Review Begins

From: Peter Dimov (pdimov_at_[hidden])
Date: 2024-12-11 17:43:06

Tom Kent wrote:
> For example, there have been timing attacks against SHA-2/HMAC where the
> difference in the amount of time processing takes can leak information about
> the secret key.
> https://dl.acm.org/doi/10.1007/978-3-030-89915-8_2

This is an attack against a hardware implementation of HMAC-SHA2-256. The
paper doesn't seem to be freely available, but I _think_ that it relies on data
leaks via changes in power consumption.

This doesn't seem applicable to software implementations, and I wasn't able
to find attacks against software HMAC-SHA2-256. (Admittedly, after a not
that exhaustive search attempt.)

Either way, if you think that not having a SHA-2 implementation in Boost
will increase the resistance of the collective body of C++ code against side
channel attacks, I can only say that I believe you are very much mistaken.