On Mon, Dec 2, 2019 at 9:47 PM Niels Möller nisse@lysator.liu.se wrote:
name size sign/ms verify/ms rsa 2048 0.8881 27.1422rsa (openssl) 2048 1.4249 45.2295
rsa-tr 2048 0.4257 29.1152rsa-tr (openssl) 2048 1.3735 46.1692
The above explains why Nettle's rsa-tr is much slower than the non-tr version. But it's disappointing that there also looks like a pretty large general slowdown.
I think most of the running time for RSA operations, except for modular inversion, are in wel-tuned GMP functions. For best speed, make sure GMP is either compiled with --enable-fat, or configured for the machine it's running on, and use a recent version. To track down any problems, it's important to know more precisely what processor it's running on and how gmp was configured.
That seemed trivial before I wrote this email, but that was actually the case. The fedora maintainer had removed the --enable-fat option in a seemingly unrelated commit. I've reported it at: https://bugzilla.redhat.com/show_bug.cgi?id=1779060
Is "Smooth CRT" something that I should look up?
I do not know more about it. I only saw that in the openssl commit claims a speed up but without any numbers.
regards, Nikos