vboot2: Add support for modexp acceleration

Add vb2ex_hwcrypto_modexp support to accelerate only calculation part of
RSA and we can handle the rest. Instead of relying on opaque hardware
accleration for all RSA verification process, this will enable us to
maintain our security level while enhancing overall speed of

TEST=make runtests

Signed-off-by: Kangheui Won <khwon@chromium.org>
Change-Id: I6f9fc919c4215964158815a58a9f1b338c2a76a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2444809
Reviewed-by: Julius Werner <jwerner@chromium.org>
4 files changed