From e30d764b7fe33221c7959bf79b461afbf7caf868 Mon Sep 17 00:00:00 2001 From: Henry de Valence Date: Thu, 5 Apr 2018 14:49:59 -0700 Subject: [PATCH] Add eq testing stub --- docs/ristretto-notes.md | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/docs/ristretto-notes.md b/docs/ristretto-notes.md index 707c299..8999137 100644 --- a/docs/ristretto-notes.md +++ b/docs/ristretto-notes.md @@ -448,6 +448,17 @@ XXX write up details # Equality Testing +Testing equality of two Ristretto points means testing whether they +are equal in the quotient group, i.e., whether they lie in the same +coset of \\(\mathcal E[4] \\) (for the cofactor-\\(8\\) case) or +\\(\mathcal E[2] \\) (for the cofactor-\\(4\\) case). + +Equality testing of points on the Edwards curve requires comparing to +affine coordinates, which requires an expensive inversion. However, +testing whether two points lie in the same coset can be done in +projective coordinates, making it actually *easier* than equality +testing in the original non-quotient group. + XXX write up details # Elligator