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upstream: Ensure that D mod (P-1) and D mod (Q-1) are calculated in

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constant time.

This avoids a potential side channel timing leak.

ok djm@ markus@

OpenBSD-Commit-ID: 71ff3c16be03290e63d8edab8fac053d8a82968c
This commit is contained in:
jsing@openbsd.org 2018-02-14 16:27:24 +00:00 committed by Damien Miller
parent 4270efad70
commit d2b3db2860
1 changed files with 10 additions and 8 deletions
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18
ssh-rsa.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: ssh-rsa.c,v 1.65 2018/02/07 05:17:56 jsing Exp $ */ /* $OpenBSD: ssh-rsa.c,v 1.66 2018/02/14 16:27:24 jsing Exp $ */
/* /*
* Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org> * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org>
* *
@ -79,13 +79,12 @@ rsa_hash_alg_nid(int type)
} }
} }
/* calculate p-1 and q-1 */
int int
ssh_rsa_generate_additional_parameters(struct sshkey *key) ssh_rsa_generate_additional_parameters(struct sshkey *key)
{ {
RSA *rsa;
BIGNUM *aux = NULL; BIGNUM *aux = NULL;
BN_CTX *ctx = NULL; BN_CTX *ctx = NULL;
BIGNUM d;
int r; int r;
if (key == NULL || key->rsa == NULL || if (key == NULL || key->rsa == NULL ||
@ -98,12 +97,15 @@ ssh_rsa_generate_additional_parameters(struct sshkey *key)
r = SSH_ERR_ALLOC_FAIL; r = SSH_ERR_ALLOC_FAIL;
goto out; goto out;
} }
rsa = key->rsa; BN_set_flags(aux, BN_FLG_CONSTTIME);
if ((BN_sub(aux, rsa->q, BN_value_one()) == 0) || BN_init(&d);
(BN_mod(rsa->dmq1, rsa->d, aux, ctx) == 0) || BN_with_flags(&d, key->rsa->d, BN_FLG_CONSTTIME);
(BN_sub(aux, rsa->p, BN_value_one()) == 0) ||
(BN_mod(rsa->dmp1, rsa->d, aux, ctx) == 0)) { if ((BN_sub(aux, key->rsa->q, BN_value_one()) == 0) ||
(BN_mod(key->rsa->dmq1, &d, aux, ctx) == 0) ||
(BN_sub(aux, key->rsa->p, BN_value_one()) == 0) ||
(BN_mod(key->rsa->dmp1, &d, aux, ctx) == 0)) {
r = SSH_ERR_LIBCRYPTO_ERROR; r = SSH_ERR_LIBCRYPTO_ERROR;
goto out; goto out;
} }