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dfe237a93b
ecc: Add blinding for ECDSA. * cipher/ecc-ecdsa.c (_gcry_ecc_ecdsa_sign): Blind secret D with randomized nonce B. (From OE-Core rev: e05c9b1be8e852293dfc7026f0e3178c3bc5444d) Signed-off-by: Armin Kuster <akuster808@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
77 lines
2.5 KiB
Diff
77 lines
2.5 KiB
Diff
From 9010d1576e278a4274ad3f4aa15776c28f6ba965 Mon Sep 17 00:00:00 2001
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From: NIIBE Yutaka <gniibe@fsij.org>
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Date: Wed, 13 Jun 2018 15:28:58 +0900
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Subject: [PATCH] ecc: Add blinding for ECDSA.
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* cipher/ecc-ecdsa.c (_gcry_ecc_ecdsa_sign): Blind secret D with
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randomized nonce B.
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--
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Reported-by: Keegan Ryan <Keegan.Ryan@nccgroup.trust>
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CVE-id: CVE-2018-0495
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Upstream-Status: Backport [http://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=commit;h=9010d1576e278a4274ad3f4aa15776c28f6ba965]
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Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
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Signed-off-by: Jagadeesh Krishnanjanappa <jkrishnanjanappa@mvista.com>
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---
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cipher/ecc-ecdsa.c | 20 ++++++++++++++++++--
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1 file changed, 18 insertions(+), 2 deletions(-)
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diff --git a/cipher/ecc-ecdsa.c b/cipher/ecc-ecdsa.c
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index 1484830b..140e8c09 100644
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--- a/cipher/ecc-ecdsa.c
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+++ b/cipher/ecc-ecdsa.c
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@@ -50,6 +50,8 @@ _gcry_ecc_ecdsa_sign (gcry_mpi_t input, ECC_secret_key *skey,
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const void *abuf;
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unsigned int abits, qbits;
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mpi_ec_t ctx;
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+ gcry_mpi_t b; /* Random number needed for blinding. */
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+ gcry_mpi_t bi; /* multiplicative inverse of B. */
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if (DBG_CIPHER)
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log_mpidump ("ecdsa sign hash ", input );
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@@ -61,6 +63,15 @@ _gcry_ecc_ecdsa_sign (gcry_mpi_t input, ECC_secret_key *skey,
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if (rc)
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return rc;
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+ b = mpi_snew (qbits);
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+ bi = mpi_snew (qbits);
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+ do
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+ {
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+ _gcry_mpi_randomize (b, qbits, GCRY_WEAK_RANDOM);
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+ mpi_mod (b, b, skey->E.n);
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+ }
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+ while (!mpi_invm (bi, b, skey->E.n));
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+
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k = NULL;
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dr = mpi_alloc (0);
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sum = mpi_alloc (0);
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@@ -115,8 +126,11 @@ _gcry_ecc_ecdsa_sign (gcry_mpi_t input, ECC_secret_key *skey,
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}
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while (!mpi_cmp_ui (r, 0));
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- mpi_mulm (dr, skey->d, r, skey->E.n); /* dr = d*r mod n */
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- mpi_addm (sum, hash, dr, skey->E.n); /* sum = hash + (d*r) mod n */
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+ mpi_mulm (dr, b, skey->d, skey->E.n);
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+ mpi_mulm (dr, dr, r, skey->E.n); /* dr = d*r mod n (blinded with b) */
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+ mpi_mulm (sum, b, hash, skey->E.n);
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+ mpi_addm (sum, sum, dr, skey->E.n); /* sum = hash + (d*r) mod n (blinded with b) */
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+ mpi_mulm (sum, bi, sum, skey->E.n); /* undo blinding by b^-1 */
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mpi_invm (k_1, k, skey->E.n); /* k_1 = k^(-1) mod n */
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mpi_mulm (s, k_1, sum, skey->E.n); /* s = k^(-1)*(hash+(d*r)) mod n */
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}
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@@ -129,6 +143,8 @@ _gcry_ecc_ecdsa_sign (gcry_mpi_t input, ECC_secret_key *skey,
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}
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leave:
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+ mpi_free (b);
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+ mpi_free (bi);
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_gcry_mpi_ec_free (ctx);
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point_free (&I);
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mpi_free (x);
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--
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2.13.3
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