Make DH opaque

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

diff --git a/crypto/dh/dh_check.c b/crypto/dh/dh_check.c
index d85696b462863287a747747b9a0d7ff75373476a..5d1426580291c05b02d3ce2d911ecb6c5a6930b6 100644 (file)
--- a/crypto/dh/dh_check.c
+++ b/crypto/dh/dh_check.c
@@ -58,7 +58,7 @@
 #include <stdio.h>
 #include "internal/cryptlib.h"
 #include <openssl/bn.h>
-#include <openssl/dh.h>
+#include "dh_locl.h"
 
 /*-
  * Check that p is a safe prime and
@@ -142,22 +142,37 @@ int DH_check(const DH *dh, int *ret)
 int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *ret)
 {
     int ok = 0;
-    BIGNUM *q = NULL;
+    BIGNUM *tmp = NULL;
+    BN_CTX *ctx = NULL;
 
     *ret = 0;
-    q = BN_new();
-    if (q == NULL)
+    ctx = BN_CTX_new();
+    if (ctx == NULL)
         goto err;
-    BN_set_word(q, 1);
-    if (BN_cmp(pub_key, q) <= 0)
+    BN_CTX_start(ctx);
+    tmp = BN_CTX_get(ctx);
+    if (tmp == NULL || !BN_set_word(tmp, 1))
+        goto err;
+    if (BN_cmp(pub_key, tmp) <= 0)
         *ret |= DH_CHECK_PUBKEY_TOO_SMALL;
-    BN_copy(q, dh->p);
-    BN_sub_word(q, 1);
-    if (BN_cmp(pub_key, q) >= 0)
+    if (BN_copy(tmp, dh->p) == NULL || !BN_sub_word(tmp, 1))
+        goto err;
+    if (BN_cmp(pub_key, tmp) >= 0)
         *ret |= DH_CHECK_PUBKEY_TOO_LARGE;
 
+    if (dh->q != NULL) {
+        /* Check pub_key^q == 1 mod p */
+        if (!BN_mod_exp(tmp, pub_key, dh->q, dh->p, ctx))
+            goto err;
+        if (!BN_is_one(tmp))
+            *ret |= DH_CHECK_PUBKEY_INVALID;
+    }
+
     ok = 1;
  err:
-    BN_free(q);
+    if (ctx != NULL) {
+        BN_CTX_end(ctx);
+        BN_CTX_free(ctx);
+    }
     return (ok);
 }