+++ /dev/null
-From 6450224f3e3c78fdfa37eadbe6ada8301279f6c1 Mon Sep 17 00:00:00 2001
-From: =?UTF-8?q?Niels=20M=C3=B6ller?= <nisse@lysator.liu.se>
-Date: Mon, 20 Jun 2016 20:04:56 +0200
-Subject: Use mpz_powm_sec.
-Subject: Check for invalid keys, with even p, in dsa_sign.
-Subject: Reject invalid keys, with even moduli, in rsa_compute_root_tr.
-Subject: Reject invalid RSA keys with even modulo.
-
-Patch status: upstream
-
-Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
-
-diff --git a/bignum.h b/bignum.h
-index 24158e0..0d30534 100644
---- a/bignum.h
-+++ b/bignum.h
-@@ -53,6 +53,8 @@
- # define mpz_combit mpz_combit
- # define mpz_import mpz_import
- # define mpz_export mpz_export
-+/* Side-channel silent powm not available in mini-gmp. */
-+# define mpz_powm_sec mpz_powm
- #else
- # include <gmp.h>
- #endif
-diff --git a/configure.ac b/configure.ac
-index e1ee64c..1e88477 100644
---- a/configure.ac
-+++ b/configure.ac
-@@ -236,9 +236,9 @@ fi
- # Checks for libraries
- if test "x$enable_public_key" = "xyes" ; then
- if test "x$enable_mini_gmp" = "xno" ; then
-- AC_CHECK_LIB(gmp, __gmpz_getlimbn,,
-+ AC_CHECK_LIB(gmp, __gmpz_powm_sec,,
- [AC_MSG_WARN(
-- [GNU MP not found, or not 3.1 or up, see http://gmplib.org/.
-+ [GNU MP not found, or too old. GMP-5.0 or later is needed, see http://gmplib.org/.
- Support for public key algorithms will be unavailable.])]
- enable_public_key=no)
-
-diff --git a/dsa-sign.c b/dsa-sign.c
-index 62c7d4a..b713743 100644
---- a/dsa-sign.c
-+++ b/dsa-sign.c
-@@ -56,6 +56,11 @@ dsa_sign(const struct dsa_params *params,
- mpz_t tmp;
- int res;
-
-+ /* Check that p is odd, so that invalid keys don't result in a crash
-+ inside mpz_powm_sec. */
-+ if (mpz_even_p (params->p))
-+ return 0;
-+
- /* Select k, 0<k<q, randomly */
- mpz_init_set(tmp, params->q);
- mpz_sub_ui(tmp, tmp, 1);
-@@ -65,7 +70,7 @@ dsa_sign(const struct dsa_params *params,
- mpz_add_ui(k, k, 1);
-
- /* Compute r = (g^k (mod p)) (mod q) */
-- mpz_powm(tmp, params->g, k, params->p);
-+ mpz_powm_sec(tmp, params->g, k, params->p);
- mpz_fdiv_r(signature->r, tmp, params->q);
-
- /* Compute hash */
-diff --git a/rsa-blind.c b/rsa-blind.c
-index 7662f50..16b03d7 100644
---- a/rsa-blind.c
-+++ b/rsa-blind.c
-@@ -61,7 +61,7 @@ _rsa_blind (const struct rsa_public_key *pub,
- while (!mpz_invert (ri, r, pub->n));
-
- /* c = c*(r^e) mod n */
-- mpz_powm(r, r, pub->e, pub->n);
-+ mpz_powm_sec(r, r, pub->e, pub->n);
- mpz_mul(c, c, r);
- mpz_fdiv_r(c, c, pub->n);
-
-diff --git a/rsa-sign-tr.c b/rsa-sign-tr.c
-index 3d80ed4..8542cae 100644
---- a/rsa-sign-tr.c
-+++ b/rsa-sign-tr.c
-@@ -60,7 +60,7 @@ rsa_blind (const struct rsa_public_key *pub,
- while (!mpz_invert (ri, r, pub->n));
-
- /* c = c*(r^e) mod n */
-- mpz_powm(r, r, pub->e, pub->n);
-+ mpz_powm_sec(r, r, pub->e, pub->n);
- mpz_mul(c, m, r);
- mpz_fdiv_r(c, c, pub->n);
-
-@@ -88,6 +88,14 @@ rsa_compute_root_tr(const struct rsa_public_key *pub,
- int res;
- mpz_t t, mb, xb, ri;
-
-+ /* mpz_powm_sec handles only odd moduli. If p, q or n is even, the
-+ key is invalid and rejected by rsa_private_key_prepare. However,
-+ some applications, notably gnutls, don't use this function, and
-+ we don't want an invalid key to lead to a crash down inside
-+ mpz_powm_sec. So do an additional check here. */
-+ if (mpz_even_p (pub->n) || mpz_even_p (key->p) || mpz_even_p (key->q))
-+ return 0;
-+
- mpz_init (mb);
- mpz_init (xb);
- mpz_init (ri);
-@@ -97,7 +105,7 @@ rsa_compute_root_tr(const struct rsa_public_key *pub,
-
- rsa_compute_root (key, xb, mb);
-
-- mpz_powm(t, xb, pub->e, pub->n);
-+ mpz_powm_sec(t, xb, pub->e, pub->n);
- res = (mpz_cmp(mb, t) == 0);
-
- if (res)
-diff --git a/rsa-sign.c b/rsa-sign.c
-index eba7388..4832352 100644
---- a/rsa-sign.c
-+++ b/rsa-sign.c
-@@ -96,11 +96,11 @@ rsa_compute_root(const struct rsa_private_key *key,
-
- /* Compute xq = m^d % q = (m%q)^b % q */
- mpz_fdiv_r(xq, m, key->q);
-- mpz_powm(xq, xq, key->b, key->q);
-+ mpz_powm_sec(xq, xq, key->b, key->q);
-
- /* Compute xp = m^d % p = (m%p)^a % p */
- mpz_fdiv_r(xp, m, key->p);
-- mpz_powm(xp, xp, key->a, key->p);
-+ mpz_powm_sec(xp, xp, key->a, key->p);
-
- /* Set xp' = (xp - xq) c % p. */
- mpz_sub(xp, xp, xq);
-diff --git a/rsa.c b/rsa.c
-index 19d93de..f594140 100644
---- a/rsa.c
-+++ b/rsa.c
-@@ -58,13 +58,18 @@ rsa_public_key_clear(struct rsa_public_key *key)
- }
-
- /* Computes the size, in octets, of a the modulo. Returns 0 if the
-- * modulo is too small to be useful. */
--
-+ * modulo is too small to be useful, or otherwise appears invalid. */
- size_t
- _rsa_check_size(mpz_t n)
- {
- /* Round upwards */
-- size_t size = (mpz_sizeinbase(n, 2) + 7) / 8;
-+ size_t size;
-+
-+ /* Even moduli are invalid, and not supported by mpz_powm_sec. */
-+ if (mpz_even_p (n))
-+ return 0;
-+
-+ size = (mpz_sizeinbase(n, 2) + 7) / 8;
-
- if (size < RSA_MINIMUM_N_OCTETS)
- return 0;
-diff --git a/testsuite/rsa-test.c b/testsuite/rsa-test.c
-index e9b1c03..a429664 100644
---- a/testsuite/rsa-test.c
-+++ b/testsuite/rsa-test.c
-@@ -57,6 +57,13 @@ test_main(void)
-
- test_rsa_sha512(&pub, &key, expected);
-
-+ /* Test detection of invalid keys with even modulo */
-+ mpz_clrbit (pub.n, 0);
-+ ASSERT (!rsa_public_key_prepare (&pub));
-+
-+ mpz_clrbit (key.p, 0);
-+ ASSERT (!rsa_private_key_prepare (&key));
-+
- /* 777-bit key, generated by
- *
- * lsh-keygen -a rsa -l 777 -f advanced-hex
---
-2.7.3
-
projects / buildroot.git / commitdiff