From: Kunxian Xia Date: Mon, 9 Apr 2018 12:38:51 +0000 (-0400) Subject: Correct the equation for Y' in the comment of point_double function X-Git-Tag: OpenSSL_1_1_1-pre5~37 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=eb8e052c4b43551f205b328e3a6568309c9e042e;p=oweals%2Fopenssl.git Correct the equation for Y' in the comment of point_double function CLA: trivial Reviewed-by: Matt Caswell Reviewed-by: Rich Salz (Merged from https://github.com/openssl/openssl/pull/5908) --- diff --git a/crypto/ec/ecp_nistp224.c b/crypto/ec/ecp_nistp224.c index 346f84dcde..5b8da3f817 100644 --- a/crypto/ec/ecp_nistp224.c +++ b/crypto/ec/ecp_nistp224.c @@ -813,7 +813,7 @@ static void copy_conditional(felem out, const felem in, limb icopy) * Double an elliptic curve point: * (X', Y', Z') = 2 * (X, Y, Z), where * X' = (3 * (X - Z^2) * (X + Z^2))^2 - 8 * X * Y^2 - * Y' = 3 * (X - Z^2) * (X + Z^2) * (4 * X * Y^2 - X') - 8 * Y^2 + * Y' = 3 * (X - Z^2) * (X + Z^2) * (4 * X * Y^2 - X') - 8 * Y^4 * Z' = (Y + Z)^2 - Y^2 - Z^2 = 2 * Y * Z * Outputs can equal corresponding inputs, i.e., x_out == x_in is allowed, * while x_out == y_in is not (maybe this works, but it's not tested).