From 9be2984bfbff9a83e7b38f47ac87c677e9a9a0b8 Mon Sep 17 00:00:00 2001
From: Adam Langley <agl@chromium.org>
Date: Thu, 24 Jan 2013 16:27:28 -0500
Subject: dsa_nonce

Adds the option to calculate (EC)DSA nonces by hashing the message and
private key along with entropy.
---
 crypto/bn/bn.h          |  6 +++++
 crypto/bn/bn_err.c      |  2 ++
 crypto/bn/bn_rand.c     | 70 +++++++++++++++++++++++++++++++++++++++++++++++++
 crypto/dsa/dsa.h        | 10 +++++--
 crypto/dsa/dsa_err.c    |  1 +
 crypto/dsa/dsa_ossl.c   | 28 ++++++++++++++++----
 crypto/dsa/dsa_sign.c   |  9 ++++++-
 crypto/ec/ec.h          | 11 ++++++++
 crypto/ec/ec_key.c      | 12 +++++++++
 crypto/ec/ec_lcl.h      |  1 +
 crypto/ecdsa/ecdsa.h    |  1 +
 crypto/ecdsa/ecs_err.c  |  1 +
 crypto/ecdsa/ecs_locl.h |  5 ++--
 crypto/ecdsa/ecs_ossl.c | 38 ++++++++++++++++++++-------
 crypto/ecdsa/ecs_sign.c | 10 ++++++-
 15 files changed, 185 insertions(+), 20 deletions(-)

diff --git a/crypto/bn/bn.h b/crypto/bn/bn.h
index f34248e..9281ce5 100644
--- a/crypto/bn/bn.h
+++ b/crypto/bn/bn.h
@@ -692,6 +692,10 @@ const BIGNUM *BN_get0_nist_prime_256(void);
 const BIGNUM *BN_get0_nist_prime_384(void);
 const BIGNUM *BN_get0_nist_prime_521(void);
 
+int BN_generate_dsa_nonce(BIGNUM *out, const BIGNUM *range, const BIGNUM *priv,
+			  const unsigned char *message, size_t message_len,
+			  BN_CTX *ctx);
+
 /* library internal functions */
 
 #define bn_expand(a,bits) ((((((bits+BN_BITS2-1))/BN_BITS2)) <= (a)->dmax)?\
@@ -842,6 +846,7 @@ void ERR_load_BN_strings(void);
 #define BN_F_BN_EXP					 123
 #define BN_F_BN_EXPAND2					 108
 #define BN_F_BN_EXPAND_INTERNAL				 120
+#define BN_F_BN_GENERATE_DSA_NONCE			 140
 #define BN_F_BN_GF2M_MOD				 131
 #define BN_F_BN_GF2M_MOD_EXP				 132
 #define BN_F_BN_GF2M_MOD_MUL				 133
@@ -881,6 +886,7 @@ void ERR_load_BN_strings(void);
 #define BN_R_NOT_INITIALIZED				 107
 #define BN_R_NO_INVERSE					 108
 #define BN_R_NO_SOLUTION				 116
+#define BN_R_PRIVATE_KEY_TOO_LARGE			 117
 #define BN_R_P_IS_NOT_PRIME				 112
 #define BN_R_TOO_MANY_ITERATIONS			 113
 #define BN_R_TOO_MANY_TEMPORARY_VARIABLES		 109
diff --git a/crypto/bn/bn_err.c b/crypto/bn/bn_err.c
index cfe2eb9..f722b52 100644
--- a/crypto/bn/bn_err.c
+++ b/crypto/bn/bn_err.c
@@ -87,6 +87,7 @@ static ERR_STRING_DATA BN_str_functs[]=
 {ERR_FUNC(BN_F_BN_EXP),	"BN_exp"},
 {ERR_FUNC(BN_F_BN_EXPAND2),	"bn_expand2"},
 {ERR_FUNC(BN_F_BN_EXPAND_INTERNAL),	"BN_EXPAND_INTERNAL"},
+{ERR_FUNC(BN_F_BN_GENERATE_DSA_NONCE),	"BN_generate_dsa_nonce"},
 {ERR_FUNC(BN_F_BN_GF2M_MOD),	"BN_GF2m_mod"},
 {ERR_FUNC(BN_F_BN_GF2M_MOD_EXP),	"BN_GF2m_mod_exp"},
 {ERR_FUNC(BN_F_BN_GF2M_MOD_MUL),	"BN_GF2m_mod_mul"},
@@ -129,6 +130,7 @@ static ERR_STRING_DATA BN_str_reasons[]=
 {ERR_REASON(BN_R_NOT_INITIALIZED)        ,"not initialized"},
 {ERR_REASON(BN_R_NO_INVERSE)             ,"no inverse"},
 {ERR_REASON(BN_R_NO_SOLUTION)            ,"no solution"},
+{ERR_REASON(BN_R_PRIVATE_KEY_TOO_LARGE)  ,"private key too large"},
 {ERR_REASON(BN_R_P_IS_NOT_PRIME)         ,"p is not prime"},
 {ERR_REASON(BN_R_TOO_MANY_ITERATIONS)    ,"too many iterations"},
 {ERR_REASON(BN_R_TOO_MANY_TEMPORARY_VARIABLES),"too many temporary variables"},
diff --git a/crypto/bn/bn_rand.c b/crypto/bn/bn_rand.c
index b376c28..55676f0 100644
--- a/crypto/bn/bn_rand.c
+++ b/crypto/bn/bn_rand.c
@@ -114,6 +114,7 @@
 #include "cryptlib.h"
 #include "bn_lcl.h"
 #include <openssl/rand.h>
+#include <openssl/sha.h>
 
 static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
 	{
@@ -303,3 +304,72 @@ int	BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range)
 	{
 	return bn_rand_range(1, r, range);
 	}
+
+#ifndef OPENSSL_NO_SHA512
+/* BN_generate_dsa_nonce generates a random number 0 <= out < range. Unlike
+ * BN_rand_range, it also includes the contents of |priv| and |message| in the
+ * generation so that an RNG failure isn't fatal as long as |priv| remains
+ * secret. This is intended for use in DSA and ECDSA where an RNG weakness
+ * leads directly to private key exposure unless this function is used. */
+int BN_generate_dsa_nonce(BIGNUM *out, const BIGNUM *range, const BIGNUM* priv,
+			  const unsigned char *message, size_t message_len,
+			  BN_CTX *ctx)
+	{
+	SHA512_CTX sha;
+	/* We use 512 bits of random data per iteration to
+	 * ensure that we have at least |range| bits of randomness. */
+	unsigned char random_bytes[64];
+	unsigned char digest[SHA512_DIGEST_LENGTH];
+	unsigned done, todo;
+	/* We generate |range|+8 bytes of random output. */
+	const unsigned num_k_bytes = BN_num_bytes(range) + 8;
+	unsigned char private_bytes[96];
+	unsigned char *k_bytes;
+	int ret = 0;
+
+	k_bytes = OPENSSL_malloc(num_k_bytes);
+	if (!k_bytes)
+		goto err;
+
+	/* We copy |priv| into a local buffer to avoid exposing its length. */
+	todo = sizeof(priv->d[0])*priv->top;
+	if (todo > sizeof(private_bytes))
+		{
+		/* No reasonable DSA or ECDSA key should have a private key
+		 * this large and we don't handle this case in order to avoid
+		 * leaking the length of the private key. */
+		BNerr(BN_F_BN_GENERATE_DSA_NONCE, BN_R_PRIVATE_KEY_TOO_LARGE);
+		goto err;
+		}
+	memcpy(private_bytes, priv->d, todo);
+	memset(private_bytes + todo, 0, sizeof(private_bytes) - todo);
+
+	for (done = 0; done < num_k_bytes;) {
+		if (RAND_bytes(random_bytes, sizeof(random_bytes)) != 1)
+			goto err;
+		SHA512_Init(&sha);
+		SHA512_Update(&sha, &done, sizeof(done));
+		SHA512_Update(&sha, private_bytes, sizeof(private_bytes));
+		SHA512_Update(&sha, message, message_len);
+		SHA512_Update(&sha, random_bytes, sizeof(random_bytes));
+		SHA512_Final(digest, &sha);
+
+		todo = num_k_bytes - done;
+		if (todo > SHA512_DIGEST_LENGTH)
+			todo = SHA512_DIGEST_LENGTH;
+		memcpy(k_bytes + done, digest, todo);
+		done += todo;
+	}
+
+	if (!BN_bin2bn(k_bytes, num_k_bytes, out))
+		goto err;
+	if (BN_mod(out, out, range, ctx) != 1)
+		goto err;
+	ret = 1;
+
+err:
+	if (k_bytes)
+		OPENSSL_free(k_bytes);
+	return ret;
+	}
+#endif  /* OPENSSL_NO_SHA512 */
diff --git a/crypto/dsa/dsa.h b/crypto/dsa/dsa.h
index b448d2a..71ef572 100644
--- a/crypto/dsa/dsa.h
+++ b/crypto/dsa/dsa.h
@@ -96,6 +96,10 @@
                                               * faster variable sliding window method to
                                               * be used for all exponents.
                                               */
+#define DSA_FLAG_NONCE_FROM_HASH	0x04 /* Causes the DSA nonce to be calculated
+						from SHA512(private_key + H(message) +
+						random). This strengthens DSA against a
+						weak PRNG. */
 
 
 /* If this flag is set the DSA method is FIPS compliant and can be used
@@ -131,8 +135,9 @@ struct dsa_method
 	{
 	const char *name;
 	DSA_SIG * (*dsa_do_sign)(const unsigned char *dgst, int dlen, DSA *dsa);
-	int (*dsa_sign_setup)(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
-								BIGNUM **rp);
+	int (*dsa_sign_setup)(DSA *dsa, BN_CTX *ctx_in,
+			      BIGNUM **kinvp, BIGNUM **rp,
+			      const unsigned char *dgst, int dlen);
 	int (*dsa_do_verify)(const unsigned char *dgst, int dgst_len,
 			     DSA_SIG *sig, DSA *dsa);
 	int (*dsa_mod_exp)(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
@@ -325,6 +330,7 @@ void ERR_load_DSA_strings(void);
 #define DSA_R_MISSING_PARAMETERS			 101
 #define DSA_R_MODULUS_TOO_LARGE				 103
 #define DSA_R_NEED_NEW_SETUP_VALUES			 110
+#define DSA_R_NONCE_CANNOT_BE_PRECOMPUTED		 112
 #define DSA_R_NON_FIPS_DSA_METHOD			 111
 #define DSA_R_NO_PARAMETERS_SET				 107
 #define DSA_R_PARAMETER_ENCODING_ERROR			 105
diff --git a/crypto/dsa/dsa_err.c b/crypto/dsa/dsa_err.c
index 00545b7..e6171cc 100644
--- a/crypto/dsa/dsa_err.c
+++ b/crypto/dsa/dsa_err.c
@@ -109,6 +109,7 @@ static ERR_STRING_DATA DSA_str_reasons[]=
 {ERR_REASON(DSA_R_MISSING_PARAMETERS)    ,"missing parameters"},
 {ERR_REASON(DSA_R_MODULUS_TOO_LARGE)     ,"modulus too large"},
 {ERR_REASON(DSA_R_NEED_NEW_SETUP_VALUES) ,"need new setup values"},
+{ERR_REASON(DSA_R_NONCE_CANNOT_BE_PRECOMPUTED),"nonce cannot be precomputed"},
 {ERR_REASON(DSA_R_NON_FIPS_DSA_METHOD)   ,"non fips dsa method"},
 {ERR_REASON(DSA_R_NO_PARAMETERS_SET)     ,"no parameters set"},
 {ERR_REASON(DSA_R_PARAMETER_ENCODING_ERROR),"parameter encoding error"},
diff --git a/crypto/dsa/dsa_ossl.c b/crypto/dsa/dsa_ossl.c
index a865a8c..15f8da2 100644
--- a/crypto/dsa/dsa_ossl.c
+++ b/crypto/dsa/dsa_ossl.c
@@ -67,7 +67,9 @@
 #include <openssl/asn1.h>
 
 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
-static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);
+static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in,
+			  BIGNUM **kinvp, BIGNUM **rp,
+			  const unsigned char *dgst, int dlen);
 static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
 			 DSA *dsa);
 static int dsa_init(DSA *dsa);
@@ -167,7 +169,8 @@ static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
 redo:
 	if ((dsa->kinv == NULL) || (dsa->r == NULL))
 		{
-		if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err;
+		if (!dsa->meth->dsa_sign_setup(dsa,ctx,&kinv,&r,dgst,dlen))
+			goto err;
 		}
 	else
 		{
@@ -226,7 +229,9 @@ err:
 	return(ret);
 	}
 
-static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
+static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in,
+			  BIGNUM **kinvp, BIGNUM **rp,
+			  const unsigned char *dgst, int dlen)
 	{
 	BN_CTX *ctx;
 	BIGNUM k,kq,*K,*kinv=NULL,*r=NULL;
@@ -252,8 +257,21 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
 
 	/* Get random k */
 	do
-		if (!BN_rand_range(&k, dsa->q)) goto err;
-	while (BN_is_zero(&k));
+		{
+#ifndef OPENSSL_NO_SHA512
+		if (dsa->flags & DSA_FLAG_NONCE_FROM_HASH)
+			{
+			/* If DSA_FLAG_NONCE_FROM_HASH is set then we calculate k from
+			 * SHA512(private_key + H(message) + random). This protects the
+			 * private key from a weak PRNG. */
+			if (!BN_generate_dsa_nonce(&k, dsa->q, dsa->priv_key, dgst,
+						   dlen, ctx))
+				goto err;
+			}
+		else
+#endif
+			if (!BN_rand_range(&k, dsa->q)) goto err;
+		} while (BN_is_zero(&k));
 	if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0)
 		{
 		BN_set_flags(&k, BN_FLG_CONSTTIME);
diff --git a/crypto/dsa/dsa_sign.c b/crypto/dsa/dsa_sign.c
index c3cc364..8ace300 100644
--- a/crypto/dsa/dsa_sign.c
+++ b/crypto/dsa/dsa_sign.c
@@ -86,7 +86,14 @@ int DSA_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
 		return 0;
 		}
 #endif
-	return dsa->meth->dsa_sign_setup(dsa, ctx_in, kinvp, rp);
+	if (dsa->flags & DSA_FLAG_NONCE_FROM_HASH)
+		{
+		/* You cannot precompute the DSA nonce if it is required to
+		 * depend on the message. */
+		DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_NONCE_CANNOT_BE_PRECOMPUTED);
+		return 0;
+		}
+	return dsa->meth->dsa_sign_setup(dsa, ctx_in, kinvp, rp, NULL, 0);
 	}
 
 DSA_SIG *DSA_SIG_new(void)
diff --git a/crypto/ec/ec.h b/crypto/ec/ec.h
index dfe8710..d008a0d 100644
--- a/crypto/ec/ec.h
+++ b/crypto/ec/ec.h
@@ -819,6 +819,17 @@ void *EC_KEY_insert_key_method_data(EC_KEY *key, void *data,
 /* wrapper functions for the underlying EC_GROUP object */
 void EC_KEY_set_asn1_flag(EC_KEY *eckey, int asn1_flag);
 
+/** Sets whether ECDSA operations with the given key will calculate their k
+ * value from SHA512(private_key + message + random) in order to protect
+ * against a weak PRNG.
+ * \param  on  Whether to calculate k from a hash or not
+ */
+void EC_KEY_set_nonce_from_hash(EC_KEY *key, int on);
+
+/** Returns the value of nonce_from_hash
+ */
+int EC_KEY_get_nonce_from_hash(const EC_KEY *key);
+
 /** Creates a table of pre-computed multiples of the generator to 
  *  accelerate further EC_KEY operations.
  *  \param  key  EC_KEY object
diff --git a/crypto/ec/ec_key.c b/crypto/ec/ec_key.c
index 7fa2475..73dd7b9 100644
--- a/crypto/ec/ec_key.c
+++ b/crypto/ec/ec_key.c
@@ -85,6 +85,7 @@ EC_KEY *EC_KEY_new(void)
 	ret->pub_key = NULL;
 	ret->priv_key= NULL;
 	ret->enc_flag= 0; 
+	ret->nonce_from_hash_flag = 0;
 	ret->conv_form = POINT_CONVERSION_UNCOMPRESSED;
 	ret->references= 1;
 	ret->method_data = NULL;
@@ -198,6 +199,7 @@ EC_KEY *EC_KEY_copy(EC_KEY *dest, const EC_KEY *src)
 
 	/* copy the rest */
 	dest->enc_flag  = src->enc_flag;
+	dest->nonce_from_hash_flag = src->nonce_from_hash_flag;
 	dest->conv_form = src->conv_form;
 	dest->version   = src->version;
 	dest->flags = src->flags;
@@ -505,6 +507,16 @@ void EC_KEY_set_enc_flags(EC_KEY *key, unsigned int flags)
 	key->enc_flag = flags;
 	}
 
+int EC_KEY_get_nonce_from_hash(const EC_KEY *key)
+	{
+	return key->nonce_from_hash_flag;
+	}
+
+void EC_KEY_set_nonce_from_hash(EC_KEY *key, int on)
+	{
+	key->nonce_from_hash_flag = on != 0;
+	}
+
 point_conversion_form_t EC_KEY_get_conv_form(const EC_KEY *key)
 	{
 	return key->conv_form;
diff --git a/crypto/ec/ec_lcl.h b/crypto/ec/ec_lcl.h
index da7967d..6f714c7 100644
--- a/crypto/ec/ec_lcl.h
+++ b/crypto/ec/ec_lcl.h
@@ -246,6 +246,7 @@ struct ec_key_st {
 	BIGNUM	 *priv_key;
 
 	unsigned int enc_flag;
+	char nonce_from_hash_flag;
 	point_conversion_form_t conv_form;
 
 	int 	references;
diff --git a/crypto/ecdsa/ecdsa.h b/crypto/ecdsa/ecdsa.h
index 7fb5254..dc6a36b 100644
--- a/crypto/ecdsa/ecdsa.h
+++ b/crypto/ecdsa/ecdsa.h
@@ -250,6 +250,7 @@ void ERR_load_ECDSA_strings(void);
 #define ECDSA_R_ERR_EC_LIB				 102
 #define ECDSA_R_MISSING_PARAMETERS			 103
 #define ECDSA_R_NEED_NEW_SETUP_VALUES			 106
+#define ECDSA_R_NONCE_CANNOT_BE_PRECOMPUTED		 108
 #define ECDSA_R_NON_FIPS_METHOD				 107
 #define ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED		 104
 #define ECDSA_R_SIGNATURE_MALLOC_FAILED			 105
diff --git a/crypto/ecdsa/ecs_err.c b/crypto/ecdsa/ecs_err.c
index 81542e6..7406c6d 100644
--- a/crypto/ecdsa/ecs_err.c
+++ b/crypto/ecdsa/ecs_err.c
@@ -85,6 +85,7 @@ static ERR_STRING_DATA ECDSA_str_reasons[]=
 {ERR_REASON(ECDSA_R_ERR_EC_LIB)          ,"err ec lib"},
 {ERR_REASON(ECDSA_R_MISSING_PARAMETERS)  ,"missing parameters"},
 {ERR_REASON(ECDSA_R_NEED_NEW_SETUP_VALUES),"need new setup values"},
+{ERR_REASON(ECDSA_R_NONCE_CANNOT_BE_PRECOMPUTED),"nonce cannot be precomputed"},
 {ERR_REASON(ECDSA_R_NON_FIPS_METHOD)     ,"non fips method"},
 {ERR_REASON(ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED),"random number generation failed"},
 {ERR_REASON(ECDSA_R_SIGNATURE_MALLOC_FAILED),"signature malloc failed"},
diff --git a/crypto/ecdsa/ecs_locl.h b/crypto/ecdsa/ecs_locl.h
index cb3be13..46f7ad9 100644
--- a/crypto/ecdsa/ecs_locl.h
+++ b/crypto/ecdsa/ecs_locl.h
@@ -70,8 +70,9 @@ struct ecdsa_method
 	const char *name;
 	ECDSA_SIG *(*ecdsa_do_sign)(const unsigned char *dgst, int dgst_len, 
 			const BIGNUM *inv, const BIGNUM *rp, EC_KEY *eckey);
-	int (*ecdsa_sign_setup)(EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv, 
-			BIGNUM **r);
+	int (*ecdsa_sign_setup)(EC_KEY *eckey, BN_CTX *ctx,
+				BIGNUM **kinv, BIGNUM **r,
+				const unsigned char *dgst, int dlen);
 	int (*ecdsa_do_verify)(const unsigned char *dgst, int dgst_len, 
 			const ECDSA_SIG *sig, EC_KEY *eckey);
 #if 0
diff --git a/crypto/ecdsa/ecs_ossl.c b/crypto/ecdsa/ecs_ossl.c
index 7725935..325aca8 100644
--- a/crypto/ecdsa/ecs_ossl.c
+++ b/crypto/ecdsa/ecs_ossl.c
@@ -60,11 +60,13 @@
 #include <openssl/err.h>
 #include <openssl/obj_mac.h>
 #include <openssl/bn.h>
+#include <openssl/rand.h>
 
 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen, 
 		const BIGNUM *, const BIGNUM *, EC_KEY *eckey);
-static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, 
-		BIGNUM **rp);
+static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
+			    BIGNUM **kinvp, BIGNUM **rp,
+			    const unsigned char *dgst, int dlen);
 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len, 
 		const ECDSA_SIG *sig, EC_KEY *eckey);
 
@@ -86,8 +88,9 @@ const ECDSA_METHOD *ECDSA_OpenSSL(void)
 	return &openssl_ecdsa_meth;
 }
 
-static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
-		BIGNUM **rp)
+static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in,
+			    BIGNUM **kinvp, BIGNUM **rp,
+			    const unsigned char *dgst, int dlen)
 {
 	BN_CTX   *ctx = NULL;
 	BIGNUM	 *k = NULL, *r = NULL, *order = NULL, *X = NULL;
@@ -136,11 +139,28 @@ static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
 	{
 		/* get random k */	
 		do
-			if (!BN_rand_range(k, order))
+#ifndef OPENSSL_NO_SHA512
+			if (EC_KEY_get_nonce_from_hash(eckey))
 			{
-				ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
-				 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);	
-				goto err;
+				if (!BN_generate_dsa_nonce(
+					k, order,
+					EC_KEY_get0_private_key(eckey),
+					dgst, dlen, ctx))
+					{
+					ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
+						 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
+					goto err;
+					}
+			}
+			else
+#endif
+			{
+				if (!BN_rand_range(k, order))
+				{
+					ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
+					 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
+					goto err;
+				}
 			}
 		while (BN_is_zero(k));
 
@@ -282,7 +302,7 @@ static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
 	{
 		if (in_kinv == NULL || in_r == NULL)
 		{
-			if (!ECDSA_sign_setup(eckey, ctx, &kinv, &ret->r))
+			if (!ecdsa->meth->ecdsa_sign_setup(eckey, ctx, &kinv, &ret->r, dgst, dgst_len))
 			{
 				ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,ERR_R_ECDSA_LIB);
 				goto err;
diff --git a/crypto/ecdsa/ecs_sign.c b/crypto/ecdsa/ecs_sign.c
index 353d5af..ea79a24 100644
--- a/crypto/ecdsa/ecs_sign.c
+++ b/crypto/ecdsa/ecs_sign.c
@@ -58,6 +58,7 @@
 #include <openssl/engine.h>
 #endif
 #include <openssl/rand.h>
+#include <openssl/err.h>
 
 ECDSA_SIG *ECDSA_do_sign(const unsigned char *dgst, int dlen, EC_KEY *eckey)
 {
@@ -102,5 +103,12 @@ int ECDSA_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
 	ECDSA_DATA *ecdsa = ecdsa_check(eckey);
 	if (ecdsa == NULL)
 		return 0;
-	return ecdsa->meth->ecdsa_sign_setup(eckey, ctx_in, kinvp, rp); 
+	if (EC_KEY_get_nonce_from_hash(eckey))
+		{
+		/* You cannot precompute the ECDSA nonce if it is required to
+		 * depend on the message. */
+		ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ECDSA_R_NONCE_CANNOT_BE_PRECOMPUTED);
+		return 0;
+		}
+	return ecdsa->meth->ecdsa_sign_setup(eckey, ctx_in, kinvp, rp, NULL, 0);
 }
-- 
1.8.5.1