In our last blog, the multi-precision math implementations in wolfCrypt were discussed with a feature comparison. In this blog we compare the performance of the SP Math All and Integer implementations.

The SP Math All library can be compiled with WOLFSSL_SP_SMALL (--enable-sp-math-all=small) to be small in size, with lower performance, to suit embedded applications. The code is both smaller and faster than the Integer math library.

Let’s take a look at how much faster SP Math All is than Integer. (Note: SP Math All configured with –-enable-sp-math-all=small -–disable-asm C_EXTRA_FLAGS=-DWC_NO_HARDEN, Integer configured with –-disable-fastmath.)

	x64	Aarch64
RSA 2048 Sign	81.43%	50.46%
RSA 2048 Verify	993.81%	522.14%
DH 2048 Key Gen	48.55%	1.82%
DH 2048 Agree	65.16%	12.71%
ECC P-256 Key Gen	45.22%	112.74%
ECC P-256 Agree	43.74%	111.60%
ECC P-256 Sign	55.01%	118.90%
ECC P-256 Verify	62.54%	127.31%

The Elliptic Curve algorithms are consistently faster across the board – about 50% on x64 and 100% on Aarch64. The RSA and DH are variable but the RSA verify operation is much faster due to the optimized exponentiation implementation in SP Math All.

Now, code size is just as important if not more so! Let’s take ARM Cortex M4 as an example.

ARM Cortex-M4 (bytes)	Integer	SP Math All
+RSA +DH +ECC	23625	18672	-20.97%
+RSA +DH -ECC	22492	16836	-25.15%
-RSA -DH +ECC	21149	18232	-13.79%

All builds are smaller with a saving of up to 25% and the code is faster! Similar reductions are seen across all CPUs.

If you have any questions or run into any issues, contact us at facts@wolfssl.com, or call us at +1 425 245 8247.