From 401c8d53d8a8cf1e79980e62bda3f946f8e07c14 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Niels=20M=C3=B6ller?= Date: Sat, 13 Mar 2021 16:29:50 +0100 Subject: [PATCH] Analogous fix to ecc_gostdsa_verify. * ecc-gostdsa-verify.c (ecc_gostdsa_verify): Use ecc_mod_mul_canonical to compute the scalars used for ecc multiplication. (cherry picked from commit fbaefb64b90cb45b7075a0ed72a92f2a1fbcd2ab) --- ChangeLog | 3 +++ ecc-gostdsa-verify.c | 6 +++--- 2 files changed, 6 insertions(+), 3 deletions(-) #diff --git a/ChangeLog b/ChangeLog #index fb2d7f66..5f8a22c2 100644 #--- a/ChangeLog #+++ b/ChangeLog #@@ -1,5 +1,8 @@ # 2021-03-13 Niels Möller # #+ * ecc-gostdsa-verify.c (ecc_gostdsa_verify): Use ecc_mod_mul_canonical #+ to compute the scalars used for ecc multiplication. #+ # * ecc-ecdsa-sign.c (ecc_ecdsa_sign): Ensure s output is reduced to # canonical range. # --- a/ecc-gostdsa-verify.c +++ b/ecc-gostdsa-verify.c @@ -102,11 +102,11 @@ ecc_gostdsa_verify (const struct ecc_cur ecc->q.invert (&ecc->q, vp, hp, vp + 2*ecc->p.size); /* z1 = s / h, P1 = z1 * G */ - ecc_mod_mul (&ecc->q, z1, sp, vp); + ecc_mod_mul_canonical (&ecc->q, z1, sp, vp, z1); /* z2 = - r / h, P2 = z2 * Y */ - ecc_mod_mul (&ecc->q, z2, rp, vp); - mpn_sub_n (z2, ecc->q.m, z2, ecc->p.size); + mpn_sub_n (hp, ecc->q.m, rp, ecc->p.size); + ecc_mod_mul_canonical (&ecc->q, z2, hp, vp, z2); /* Total storage: 5*ecc->p.size + ecc->mul_itch */ ecc->mul (ecc, P2, z2, pp, z2 + ecc->p.size);