45 lines
1.6 KiB
Diff
45 lines
1.6 KiB
Diff
From b1d6d55ece1c26fa2829e2b819b038d7b6d692b4 Mon Sep 17 00:00:00 2001
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From: Pauli <paul.dale@oracle.com>
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Date: Fri, 26 Oct 2018 10:54:58 +1000
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Subject: [PATCH 3/3] Timing vulnerability in ECDSA signature generation
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(CVE-2018-0735)
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Preallocate an extra limb for some of the big numbers to avoid a reallocation
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that can potentially provide a side channel.
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Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
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(Merged from https://github.com/openssl/openssl/pull/7486)
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(cherry picked from commit 99540ec79491f59ed8b46b4edf130e17dc907f52)
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---
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crypto/ec/ec_mult.c | 6 +++---
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1 file changed, 3 insertions(+), 3 deletions(-)
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diff --git x/crypto/ec/ec_mult.c y/crypto/ec/ec_mult.c
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index 7e1b3650e7..0e0a5e1394 100644
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--- x/crypto/ec/ec_mult.c
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+++ y/crypto/ec/ec_mult.c
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@@ -206,8 +206,8 @@ int ec_scalar_mul_ladder(const EC_GROUP *group, EC_POINT *r,
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*/
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cardinality_bits = BN_num_bits(cardinality);
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group_top = bn_get_top(cardinality);
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- if ((bn_wexpand(k, group_top + 1) == NULL)
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- || (bn_wexpand(lambda, group_top + 1) == NULL)) {
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+ if ((bn_wexpand(k, group_top + 2) == NULL)
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+ || (bn_wexpand(lambda, group_top + 2) == NULL)) {
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ECerr(EC_F_EC_SCALAR_MUL_LADDER, ERR_R_BN_LIB);
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goto err;
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}
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@@ -244,7 +244,7 @@ int ec_scalar_mul_ladder(const EC_GROUP *group, EC_POINT *r,
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* k := scalar + 2*cardinality
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*/
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kbit = BN_is_bit_set(lambda, cardinality_bits);
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- BN_consttime_swap(kbit, k, lambda, group_top + 1);
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+ BN_consttime_swap(kbit, k, lambda, group_top + 2);
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group_top = bn_get_top(group->field);
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if ((bn_wexpand(s->X, group_top) == NULL)
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--
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2.19.1
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