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CVE-2015-7511 libgcrypt: side-channel attack on ECDH with Weierstrass curves affects libgcrypt < 1.6.5 Patch 1 is a dependancy patch. simple macro name change. Patch 2 is the cve fix. (From OE-Core rev: c691ce99bd2d249d6fdc4ad58300719488fea12c) Signed-off-by: Armin Kuster <akuster@mvista.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
56 lines
1.7 KiB
Diff
56 lines
1.7 KiB
Diff
From 88e1358962e902ff1cbec8d53ba3eee46407851a Mon Sep 17 00:00:00 2001
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From: NIIBE Yutaka <gniibe@fsij.org>
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Date: Wed, 25 Nov 2015 12:46:19 +0900
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Subject: [PATCH] ecc: Constant-time multiplication for Weierstrass curve.
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* mpi/ec.c (_gcry_mpi_ec_mul_point): Use simple left-to-right binary
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method for Weierstrass curve when SCALAR is secure.
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Upstream-Status: Backport
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http://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=commit;h=88e1358962e902ff1cbec8d53ba3eee46407851a
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CVE: CVE-2015-7511 fix
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Signed-off-by: Armin Kuster <akuster@mvista.com>
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---
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mpi/ec.c | 19 +++++++++++++++----
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1 file changed, 15 insertions(+), 4 deletions(-)
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Index: libgcrypt-1.6.3/mpi/ec.c
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===================================================================
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--- libgcrypt-1.6.3.orig/mpi/ec.c
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+++ libgcrypt-1.6.3/mpi/ec.c
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@@ -1106,16 +1106,27 @@ _gcry_mpi_ec_mul_point (mpi_point_t resu
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unsigned int i, loops;
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mpi_point_struct p1, p2, p1inv;
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- if (ctx->model == MPI_EC_EDWARDS)
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+ if (ctx->model == MPI_EC_EDWARDS
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+ || (ctx->model == MPI_EC_WEIERSTRASS
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+ && mpi_is_secure (scalar)))
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{
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/* Simple left to right binary method. GECC Algorithm 3.27 */
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unsigned int nbits;
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int j;
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nbits = mpi_get_nbits (scalar);
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- mpi_set_ui (result->x, 0);
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- mpi_set_ui (result->y, 1);
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- mpi_set_ui (result->z, 1);
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+ if (ctx->model == MPI_EC_WEIERSTRASS)
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+ {
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+ mpi_set_ui (result->x, 1);
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+ mpi_set_ui (result->y, 1);
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+ mpi_set_ui (result->z, 0);
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+ }
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+ else
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+ {
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+ mpi_set_ui (result->x, 0);
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+ mpi_set_ui (result->y, 1);
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+ mpi_set_ui (result->z, 1);
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+ }
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if (mpi_is_secure (scalar))
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{
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