how to accelerate g*f by precompute?

[huyuguang]

The speed of g*f (BN curve) in mcl is very fast, much faster than normal wNAF algorithm.

In my scenario, the g is hardcoded, so I think I can accelerate the speed of g*f by precompute and cache some data, for example, 2g, 4g, 8g,16g ... , then I can convert theg*fto test_bit&add. But to my surprise, I found the test_bit&add version only slightly faster (20%~30%) than mcl version.

So, what should I do? How can I accelerate the speed for 100% or more by precompute/cache? Could you please give some suggestions (or some URLs)?

[herumi]

Use mcl/window_method.hpp as the followings:

#include <mcl/window_method.hpp>
mcl::fp::WindowMethod<G1> wm;
wm.init(P, Fr::getBitSize(), 4 /* winSize */); // precompute a table for a fixed P with 4-bit window size
Fr x;
wm.mul(P1, x); // instead of G1::mul(P1, P, x);

If increasing winSize then it requires more memory and computes more faster.

[huyuguang]

Very thanks, I will try it.

[huyuguang]

It works fine. I use init(g, bit_size, 8) and got 500% speed. Thanks again.