1 files changed, 46 insertions, 19 deletions

diff --git a/src/lib/libcrypto/dh/dh_key.c b/src/lib/libcrypto/dh/dh_key.c
index 648766a6ec..e3641ec468 100644
--- a/src/lib/libcrypto/dh/dh_key.c
+++ b/src/lib/libcrypto/dh/dh_key.c
@@ -105,7 +105,7 @@ static int generate_key(DH *dh)
         int generate_new_key=0;
         unsigned l;
         BN_CTX *ctx;
-        BN_MONT_CTX *mont;
+        BN_MONT_CTX *mont=NULL;
         BIGNUM *pub_key=NULL,*priv_key=NULL;
 
         ctx = BN_CTX_new();
@@ -128,21 +128,37 @@ static int generate_key(DH *dh)
         else
                 pub_key=dh->pub_key;
 
-        if ((dh->method_mont_p == NULL) && (dh->flags & DH_FLAG_CACHE_MONT_P))
+
+        if (dh->flags & DH_FLAG_CACHE_MONT_P)
                 {
-                if ((dh->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
-                        if (!BN_MONT_CTX_set((BN_MONT_CTX *)dh->method_mont_p,
-                                dh->p,ctx)) goto err;
+                mont = BN_MONT_CTX_set_locked(
+                                (BN_MONT_CTX **)&dh->method_mont_p,
+                                CRYPTO_LOCK_DH, dh->p, ctx);
+                if (!mont)
+                        goto err;
                 }
-        mont=(BN_MONT_CTX *)dh->method_mont_p;
 
         if (generate_new_key)
                 {
                 l = dh->length ? dh->length : BN_num_bits(dh->p)-1; /* secret exponent length */
                 if (!BN_rand(priv_key, l, 0, 0)) goto err;
                 }
-        if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, priv_key,dh->p,ctx,mont))
-                goto err;
+
+        {
+                BIGNUM local_prk;
+                BIGNUM *prk;
+
+                if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)
+                        {
+                        BN_init(&local_prk);
+                        prk = &local_prk;
+                        BN_with_flags(prk, priv_key, BN_FLG_EXP_CONSTTIME);
+                        }
+                else
+                        prk = priv_key;
+
+                if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) goto err;
+        }
                 
         dh->pub_key=pub_key;
         dh->priv_key=priv_key;
@@ -160,7 +176,7 @@ err:
 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
         {
         BN_CTX *ctx;
-        BN_MONT_CTX *mont;
+        BN_MONT_CTX *mont=NULL;
         BIGNUM *tmp;
         int ret= -1;
         int check_result;
@@ -175,15 +191,20 @@ static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
                 DHerr(DH_F_DH_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE);
                 goto err;
                 }
-        if ((dh->method_mont_p == NULL) && (dh->flags & DH_FLAG_CACHE_MONT_P))
+
+        if (dh->flags & DH_FLAG_CACHE_MONT_P)
                 {
-                if ((dh->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
-                        if (!BN_MONT_CTX_set((BN_MONT_CTX *)dh->method_mont_p,
-                                dh->p,ctx)) goto err;
+                mont = BN_MONT_CTX_set_locked(
+                                (BN_MONT_CTX **)&dh->method_mont_p,
+                                CRYPTO_LOCK_DH, dh->p, ctx);
+                if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0)
+                        {
+                        /* XXX */
+                        BN_set_flags(dh->priv_key, BN_FLG_EXP_CONSTTIME);
+                        }
+                if (!mont)
+                        goto err;
                 }
-
-        mont=(BN_MONT_CTX *)dh->method_mont_p;
-
         if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result)
                 {
                 DHerr(DH_F_DH_COMPUTE_KEY,DH_R_INVALID_PUBKEY);
@@ -197,8 +218,11 @@ static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
 
         ret=BN_bn2bin(tmp,key);
 err:
-        BN_CTX_end(ctx);
-        BN_CTX_free(ctx);
+        if (ctx != NULL)
+                {
+                BN_CTX_end(ctx);
+                BN_CTX_free(ctx);
+                }
         return(ret);
         }
 
@@ -207,7 +231,10 @@ static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
                         const BIGNUM *m, BN_CTX *ctx,
                         BN_MONT_CTX *m_ctx)
         {
-        if (a->top == 1)
+        /* If a is only one word long and constant time is false, use the faster
+         * exponenentiation function.
+         */
+        if (a->top == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0))
                 {
                 BN_ULONG A = a->d[0];
                 return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx);