Subgroup check about constantine HOT 3 CLOSED

Note that instead of using endomorphism sigma, for G1 it's faster to simply multiply-unsafely by h_eff which is 0xd201000000010001. At least from my tests.

from constantine.

I take it back. These x, y produce point which is valid if you multiply it by h_eff, but are invalid if you apply endomorphism sigma.

x=499001545268060011619089734015590154568173930614466321429631711131511181286230338880376679848890024401335766847607;
y=3934582309586258715640230772291917282844636728991757779640464479794033391537662970190753981664259511166946374555673;

from constantine.

Faster subgroup check: https://eprint.iacr.org/2021/1130.pdf

from constantine.