As with RSA, which was modified recently, this change makes it possible to

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

diff --git a/crypto/dh/dh_gen.c b/crypto/dh/dh_gen.c
index f0ee43ed8708338ae0766583916de6613ab4a8eb..1f805073cf301a6d86c815452944d1b3695d3bb9 100644 (file)
--- a/crypto/dh/dh_gen.c
+++ b/crypto/dh/dh_gen.c
@@ -56,11 +56,25 @@
  * [including the GNU Public Licence.]
  */
 
+/* NB: These functions have been upgraded - the previous prototypes are in
+ * dh_depr.c as wrappers to these ones.
+ *  - Geoff
+ */
+
 #include <stdio.h>
 #include "cryptlib.h"
 #include <openssl/bn.h>
 #include <openssl/dh.h>
 
+static int dh_builtin_genparams(DH *ret, int prime_len, int generator, BN_GENCB *cb);
+
+int DH_generate_parameters_ex(DH *ret, int prime_len, int generator, BN_GENCB *cb)
+       {
+       if(ret->meth->generate_params)
+               return ret->meth->generate_params(ret, prime_len, generator, cb);
+       return dh_builtin_genparams(ret, prime_len, generator, cb);
+       }
+
 /* We generate DH parameters as follows
  * find a prime q which is prime_len/2 bits long.
  * p=(2*q)+1 or (p-1)/2 = q
@@ -82,53 +96,67 @@
  * Since DH should be using a safe prime (both p and q are prime),
  * this generator function can take a very very long time to run.
  */
-
-DH *DH_generate_parameters(int prime_len, int generator,
-            void (*callback)(int,int,void *), void *cb_arg)
+/* Actually there is no reason to insist that 'generator' be a generator.
+ * It's just as OK (and in some sense better) to use a generator of the
+ * order-q subgroup.
+ */
+static int dh_builtin_genparams(DH *ret, int prime_len, int generator, BN_GENCB *cb)
        {
-       BIGNUM *p=NULL,*t1,*t2;
-       DH *ret=NULL;
+       BIGNUM *t1,*t2;
        int g,ok= -1;
        BN_CTX *ctx=NULL;
 
-       ret=DH_new();
-       if (ret == NULL) goto err;
        ctx=BN_CTX_new();
        if (ctx == NULL) goto err;
-       t1= &(ctx->bn[0]);
-       t2= &(ctx->bn[1]);
-       ctx->tos=2;
+       BN_CTX_start(ctx);
+       t1 = BN_CTX_get(ctx);
+       t2 = BN_CTX_get(ctx);
+       if (t1 == NULL || t2 == NULL) goto err;
+
+       /* Make sure 'ret' has the necessary elements */
+       if(!ret->p && ((ret->p = BN_new()) == NULL)) goto err;
+       if(!ret->g && ((ret->g = BN_new()) == NULL)) goto err;
        
+       if (generator <= 1)
+               {
+               DHerr(DH_F_DH_GENERATE_PARAMETERS, DH_R_BAD_GENERATOR);
+               goto err;
+               }
        if (generator == DH_GENERATOR_2)
                {
-               BN_set_word(t1,24);
-               BN_set_word(t2,11);
+               if (!BN_set_word(t1,24)) goto err;
+               if (!BN_set_word(t2,11)) goto err;
                g=2;
                }
-#ifdef undef  /* does not work for safe primes */
+#if 0 /* does not work for safe primes */
        else if (generator == DH_GENERATOR_3)
                {
-               BN_set_word(t1,12);
-               BN_set_word(t2,5);
+               if (!BN_set_word(t1,12)) goto err;
+               if (!BN_set_word(t2,5)) goto err;
                g=3;
                }
 #endif
        else if (generator == DH_GENERATOR_5)
                {
-               BN_set_word(t1,10);
-               BN_set_word(t2,3);
+               if (!BN_set_word(t1,10)) goto err;
+               if (!BN_set_word(t2,3)) goto err;
                /* BN_set_word(t3,7); just have to miss
                 * out on these ones :-( */
                g=5;
                }
        else
+               {
+               /* in the general case, don't worry if 'generator' is a
+                * generator or not: since we are using safe primes,
+                * it will generate either an order-q or an order-2q group,
+                * which both is OK */
+               if (!BN_set_word(t1,2)) goto err;
+               if (!BN_set_word(t2,1)) goto err;
                g=generator;
+               }
        
-       p=BN_generate_prime(NULL,prime_len,1,t1,t2,callback,cb_arg);
-       if (p == NULL) goto err;
-       if (callback != NULL) callback(3,0,cb_arg);
-       ret->p=p;
-       ret->g=BN_new();
+       if(!BN_generate_prime_ex(ret->p,prime_len,1,t1,t2,cb)) goto err;
+       if(!BN_GENCB_call(cb, 3, 0)) goto err;
        if (!BN_set_word(ret->g,g)) goto err;
        ok=1;
 err:
@@ -138,11 +166,10 @@ err:
                ok=0;
                }
 
-       if (ctx != NULL) BN_CTX_free(ctx);
-       if (!ok && (ret != NULL))
+       if (ctx != NULL)
                {
-               DH_free(ret);
-               ret=NULL;
+               BN_CTX_end(ctx);
+               BN_CTX_free(ctx);
                }
-       return(ret);
+       return ok;
        }