This is an algorithm for EC multiplication that emulates the Montgomery
Ladder double-and-add, but in a constant time way. An early version of
this algorithm was published in 2017, and the version implemented here
was published in 2020. The result is constant time multiply that is 85%
faster than wNAF, <10% slower than endomorphic Montgommery Ladder and
~20% faster than w/o endomorphism.

https://eprint.iacr.org/2017/669.pdf
https://web.archive.org/web/20201104025731/https://www.aimsciences.org/article/exportPdf?id=5c293be6-723e-4b97-ae1d-ff359e261cdb

Originally submitted as a pull request to my JS secp256k1 impl. I think it deserves some investigation.

Quirk: the algorithm researchers are from North Korea 😐