diff options
Diffstat (limited to 'meta/recipes-support/libgcrypt/files/CVE-2021-33560.patch')
| -rw-r--r-- | meta/recipes-support/libgcrypt/files/CVE-2021-33560.patch | 138 |
1 files changed, 53 insertions, 85 deletions
diff --git a/meta/recipes-support/libgcrypt/files/CVE-2021-33560.patch b/meta/recipes-support/libgcrypt/files/CVE-2021-33560.patch index c0d00485e6..bf26486d8b 100644 --- a/meta/recipes-support/libgcrypt/files/CVE-2021-33560.patch +++ b/meta/recipes-support/libgcrypt/files/CVE-2021-33560.patch @@ -1,109 +1,77 @@ -From 707c3c5c511ee70ad0e39ec613471f665305fbea Mon Sep 17 00:00:00 2001 +From e8b7f10be275bcedb5fc05ed4837a89bfd605c61 Mon Sep 17 00:00:00 2001 From: NIIBE Yutaka <gniibe@fsij.org> -Date: Fri, 21 May 2021 11:15:07 +0900 -Subject: [PATCH] cipher: Fix ElGamal encryption for other implementations. +Date: Tue, 13 Apr 2021 10:00:00 +0900 +Subject: [PATCH] cipher: Hardening ElGamal by introducing exponent blinding + too. -* cipher/elgamal.c (gen_k): Remove support of smaller K. -(do_encrypt): Never use smaller K. -(sign): Folllow the change of gen_k. +* cipher/elgamal.c (do_encrypt): Also do exponent blinding. -- -Cherry-pick master commit of: - 632d80ef30e13de6926d503aa697f92b5dbfbc5e +Base blinding had been introduced with USE_BLINDING. This patch add +exponent blinding as well to mitigate side-channel attack on mpi_powm. -This change basically reverts encryption changes in two commits: - - 74386120dad6b3da62db37f7044267c8ef34689b - 78531373a342aeb847950f404343a05e36022065 - -Use of smaller K for ephemeral key in ElGamal encryption is only good, -when we can guarantee that recipient's key is generated by our -implementation (or compatible). - -For detail, please see: - - Luca De Feo, Bertram Poettering, Alessandro Sorniotti, - "On the (in)security of ElGamal in OpenPGP"; - in the proceedings of CCS'2021. - -CVE-id: CVE-2021-33560 GnuPG-bug-id: 5328 -Suggested-by: Luca De Feo, Bertram Poettering, Alessandro Sorniotti Signed-off-by: NIIBE Yutaka <gniibe@fsij.org> Upstream-Status: Backport CVE: CVE-2021-33560 -Signed-off-by: Armin Kuster <akuster@mvista.com> +Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com> --- - cipher/elgamal.c | 24 ++++++------------------ - 1 file changed, 6 insertions(+), 18 deletions(-) + cipher/elgamal.c | 20 +++++++++++++++++--- + 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/cipher/elgamal.c b/cipher/elgamal.c -index 4eb52d62..ae7a631e 100644 +index 4eb52d62..9835122f 100644 --- a/cipher/elgamal.c +++ b/cipher/elgamal.c -@@ -66,7 +66,7 @@ static const char *elg_names[] = - +@@ -522,8 +522,9 @@ do_encrypt(gcry_mpi_t a, gcry_mpi_t b, gcry_mpi_t input, ELG_public_key *pkey ) + static void + decrypt (gcry_mpi_t output, gcry_mpi_t a, gcry_mpi_t b, ELG_secret_key *skey ) + { +- gcry_mpi_t t1, t2, r; ++ gcry_mpi_t t1, t2, r, r1, h; + unsigned int nbits = mpi_get_nbits (skey->p); ++ gcry_mpi_t x_blind; - static int test_keys (ELG_secret_key *sk, unsigned int nbits, int nodie); --static gcry_mpi_t gen_k (gcry_mpi_t p, int small_k); -+static gcry_mpi_t gen_k (gcry_mpi_t p); - static gcry_err_code_t generate (ELG_secret_key *sk, unsigned nbits, - gcry_mpi_t **factors); - static int check_secret_key (ELG_secret_key *sk); -@@ -189,11 +189,10 @@ test_keys ( ELG_secret_key *sk, unsigned int nbits, int nodie ) + mpi_normalize (a); + mpi_normalize (b); +@@ -534,20 +535,33 @@ decrypt (gcry_mpi_t output, gcry_mpi_t a, gcry_mpi_t b, ELG_secret_key *skey ) - /**************** - * Generate a random secret exponent k from prime p, so that k is -- * relatively prime to p-1. With SMALL_K set, k will be selected for -- * better encryption performance - this must never be used signing! -+ * relatively prime to p-1. - */ - static gcry_mpi_t --gen_k( gcry_mpi_t p, int small_k ) -+gen_k( gcry_mpi_t p ) - { - gcry_mpi_t k = mpi_alloc_secure( 0 ); - gcry_mpi_t temp = mpi_alloc( mpi_get_nlimbs(p) ); -@@ -202,18 +201,7 @@ gen_k( gcry_mpi_t p, int small_k ) - unsigned int nbits, nbytes; - char *rndbuf = NULL; + t2 = mpi_snew (nbits); + r = mpi_new (nbits); ++ r1 = mpi_new (nbits); ++ h = mpi_new (nbits); ++ x_blind = mpi_snew (nbits); -- if (small_k) -- { -- /* Using a k much lesser than p is sufficient for encryption and -- * it greatly improves the encryption performance. We use -- * Wiener's table and add a large safety margin. */ -- nbits = wiener_map( orig_nbits ) * 3 / 2; -- if( nbits >= orig_nbits ) -- BUG(); -- } -- else -- nbits = orig_nbits; -- -+ nbits = orig_nbits; + /* We need a random number of about the prime size. The random + number merely needs to be unpredictable; thus we use level 0. */ + _gcry_mpi_randomize (r, nbits, GCRY_WEAK_RANDOM); - nbytes = (nbits+7)/8; - if( DBG_CIPHER ) -@@ -492,7 +480,7 @@ do_encrypt(gcry_mpi_t a, gcry_mpi_t b, gcry_mpi_t input, ELG_public_key *pkey ) - * error code. - */ ++ /* Also, exponent blinding: x_blind = x + (p-1)*r1 */ ++ _gcry_mpi_randomize (r1, nbits, GCRY_WEAK_RANDOM); ++ mpi_set_highbit (r1, nbits - 1); ++ mpi_sub_ui (h, skey->p, 1); ++ mpi_mul (x_blind, h, r1); ++ mpi_add (x_blind, skey->x, x_blind); ++ + /* t1 = r^x mod p */ +- mpi_powm (t1, r, skey->x, skey->p); ++ mpi_powm (t1, r, x_blind, skey->p); + /* t2 = (a * r)^-x mod p */ + mpi_mulm (t2, a, r, skey->p); +- mpi_powm (t2, t2, skey->x, skey->p); ++ mpi_powm (t2, t2, x_blind, skey->p); + mpi_invm (t2, t2, skey->p); + /* t1 = (t1 * t2) mod p*/ + mpi_mulm (t1, t1, t2, skey->p); -- k = gen_k( pkey->p, 1 ); -+ k = gen_k( pkey->p ); - mpi_powm (a, pkey->g, k, pkey->p); ++ mpi_free (x_blind); ++ mpi_free (h); ++ mpi_free (r1); + mpi_free (r); + mpi_free (t2); - /* b = (y^k * input) mod p -@@ -594,7 +582,7 @@ sign(gcry_mpi_t a, gcry_mpi_t b, gcry_mpi_t input, ELG_secret_key *skey ) - * - */ - mpi_sub_ui(p_1, p_1, 1); -- k = gen_k( skey->p, 0 /* no small K ! */ ); -+ k = gen_k( skey->p ); - mpi_powm( a, skey->g, k, skey->p ); - mpi_mul(t, skey->x, a ); - mpi_subm(t, input, t, p_1 ); -- -2.30.2 +2.11.0 |