Found it! Thank you for the context info and pointer, Billy! Charlie
On Sun, Aug 28, 2022 at 12:35 AM Billy Brumley <b...@iki.fi> wrote: > > I'm new to the ECC area and trying to understand the point addition > here. I noticed the implementation of "ec_GFp_simple_add" is different from > the algorithm described at Wikipedia. Does the function > > "ec_GFp_simple_add" implement the algorithm in Wiki? Is there any > doc/paper explaining the implementation of "ec_GFp_simple_add"? > > That ECC code pre-dates Wikipedia, so the answer is "no" :) > > I believe it is A.10.5 from P1363 or extremely similar. (A crypto standard > from the late 90s---you'll have to do your own digging.) > > At a high level, it is Jacobian projective coordinates with codepath > optimizations for mixed projective-affine inputs (if applicable). > > Please keep in mind the fact that this particular code uses (any form of) > projective coordinates is only internally relevant for OpenSSL. In the > public API, all getters / setters / etc related to projective coordinates > were deprecated as of OpenSSL 3.0. > > Hope it helps, > > BBB
