Commit 992bdde6 authored by Dr. Stephen Henson's avatar Dr. Stephen Henson
Browse files

Fix the ECDSA timing attack mentioned in the paper at: 

	http://eprint.iacr.org/2011/232.pdf

Thanks to the original authors Billy Bob Brumley and Nicola Tuveri for
bringing this to our attention.
parent bbcf3a9b

CHANGES

+7 −0
Original line number Diff line number Diff line
@@ -4,6 +4,13 @@ 


 Changes between 1.0.1 and 1.1.0  [xx XXX xxxx]



  *) Add protection against ECDSA timing attacks as mentioned in the paper

     by Billy Bob Brumley and Nicola Tuveri, see:



	http://eprint.iacr.org/2011/232.pdf



     [Billy Bob Brumley and Nicola Tuveri]



  *) Add TLS v1.2 server support for client authentication. 

     [Steve Henson]

crypto/ecdsa/ecs_ossl.c

+10 −0
Original line number Diff line number Diff line
@@ -151,6 +151,16 @@ static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, 
			}

		while (BN_is_zero(k));



#ifdef ECDSA_POINT_MUL_NO_CONSTTIME

		/* We do not want timing information to leak the length of k,

		 * so we compute G*k using an equivalent scalar of fixed

		 * bit-length. */



		if (!BN_add(k, k, order)) goto err;

		if (BN_num_bits(k) <= BN_num_bits(order))

			if (!BN_add(k, k, order)) goto err;

#endif /* def(ECDSA_POINT_MUL_NO_CONSTTIME) */



		/* compute r the x-coordinate of generator * k */

		if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx))

		{