Which Curve is used？

[NickyYangYang]

hello，I want to know which Curve is used in you code. Is BLS 12-381 or BN254?

[herumi]

You can use both BN254 and BLS12-381.
test

[NickyYangYang]

The signature length of BN254 is 256 bits, the signature length of BLS12-381 is 384 bits, and BLS12-381 is more security than BN254. You use two different length standards. Why you choose BLS12-381, why not BN381? And , why you choose BN254, why not 256 bits BLS? For security reason or other reasons?

[herumi]

You can use BN254, BN381, BN462(if compiled with MCLBN_FP_UNIT_SIZE=8) and BLS12-381.
BN254 is selected for fast speed.

[NickyYangYang]

There are two 381 bits BN curve : N-381-1 and BN-381-2. The first one is a A Family of Implementation-Friendly BN Elliptic Curves, the second one is used in relic-toolkit. Which one is used when we set MCLBN_FP_UNIT_SIZE=6? And why ?

[herumi]

The default pairing parameter is BN_254, so please call init with (mcl::BN381_1).
https://github.com/herumi/mcl/blob/master/include/mcl/bn.hpp#L2063