Is there any way to imply precompute on bls12-381?

[timfaner]

Is there any way to imply precompute on bls12-381?

[herumi]

If the point Q of G2 is fixed, then you can use mclBn_precomputeG2 and mclBn_precomputedMillerLoop, but there is no way for the fixed point P of G1 now to compute a pairing e(P, Q). cf. https://github.com/herumi/mcl/blob/master/test/bn_c_test.hpp#L421-L432

[herumi]

The current library already uses those functions if BLS_ETH is not defined. Could you tell me what is your intention of precompute on bls12-381??

[timfaner]

I want to use bls12-381 to sign and verify bls signature under risc-v ISA, but bls12-381 seems a bit slower than bn254, so I'm wondering if precompute on bls12-381may speed up the verify process.

[herumi]

This library is already optimized as possible. I have no RISC-V environment, so I have some questions.

• What options do you build bls with?
• Is GMP available?
• Could you exec cd mcl && make UPDATE_ASM=1?
• What is the result uname -s and uname -m?

[timfaner]

• I built bls and mcl using -DMCL_USE_VINT -DMCL_VINT_FIXED_BUFFER -DMCL_DONT_USE_OPENSSL -DMCL_DONT_USE_XBYAK
• GMP is not available under risc-v ISA
• I'm not sure if llvm asm is supported risc-v so I turned off the
• RISC-V is a little bit same as embedded system, I works on little endian with 64bit length/

[herumi]

Does your system have llvm commands such as opt, llc (llvm-opt or...)? If so, then you may be able to make a asm code for riscv like the following commands (I've not test it.).

make src/base64.ll
opt -O3 -o - src/base64.ll | llc -O3 -o src/asm/riscv.s -relocation-model=pic
gas -o riscv.o src/asm/riscv.s
g++ -O3 -c src/fp.cpp -O3 -DNDEBUG -fPIC -I ./include -DMCL_USE_VINT -DMCL_VINT_FIXED_BUFFER -DMCL_DONT_USE_OPENSSL -DMCL_DONT_USE_XBYAK -DMCL_USE_LLVM=1 -DCYBOZU_DONT_USE_STRING -DCYBOZU_DONT_USE_EXCEPTION -DMCL_MAX_BIT_SIZE=384
ar r lib/libmcl.a fp.o  riscv.o

And make bls with lib/libmcl.a.