Make D-H safer, include well-known primes.

[openssl.git] / crypto / dh / dh_key.c

diff --git a/crypto/dh/dh_key.c b/crypto/dh/dh_key.c
index 1a0efca2c4c19c0eb319e48b2ac30d3371cac7df..cc17c8851b691daf2798cad861f56b03adb9cbb1 100644 (file)
--- a/crypto/dh/dh_key.c
+++ b/crypto/dh/dh_key.c
@@ -61,7 +61,6 @@
 #include <openssl/bn.h>
 #include <openssl/rand.h>
 #include <openssl/dh.h>
-#include <openssl/engine.h>
 
 static int generate_key(DH *dh);
 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh);
@@ -90,6 +89,7 @@ dh_bn_mod_exp,
 dh_init,
 dh_finish,
 0,
+NULL,
 NULL
 };
 
@@ -104,7 +104,7 @@ 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();
@@ -127,28 +127,43 @@ 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(&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;
        ok=1;
 err:
        if (ok != 1)
-               DHerr(DH_F_DH_GENERATE_KEY,ERR_R_BN_LIB);
+               DHerr(DH_F_GENERATE_KEY,ERR_R_BN_LIB);
 
        if ((pub_key != NULL)  && (dh->pub_key == NULL))  BN_free(pub_key);
        if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key);
@@ -159,9 +174,10 @@ 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;
 
        ctx = BN_CTX_new();
        if (ctx == NULL) goto err;
@@ -170,20 +186,32 @@ static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
        
        if (dh->priv_key == NULL)
                {
-               DHerr(DH_F_DH_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE);
+               DHerr(DH_F_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(&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;
+               }
+
+        if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result)
+               {
+               DHerr(DH_F_COMPUTE_KEY,DH_R_INVALID_PUBKEY);
+               goto err;
                }
 
-       mont=(BN_MONT_CTX *)dh->method_mont_p;
        if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key,dh->p,ctx,mont))
                {
-               DHerr(DH_F_DH_COMPUTE_KEY,ERR_R_BN_LIB);
+               DHerr(DH_F_COMPUTE_KEY,ERR_R_BN_LIB);
                goto err;
                }
 
@@ -199,7 +227,10 @@ 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);
@@ -218,6 +249,6 @@ static int dh_init(DH *dh)
 static int dh_finish(DH *dh)
        {
        if(dh->method_mont_p)
-               BN_MONT_CTX_free((BN_MONT_CTX *)dh->method_mont_p);
+               BN_MONT_CTX_free(dh->method_mont_p);
        return(1);
        }