Fixed an internal bug in rsa.c

Allow to decryption/signing using a minimal RSA key.

3 files changed, 55 insertions, 20 deletions

diff --git a/cipher/ChangeLog b/cipher/ChangeLog
index 90fc43a4..f81c5da0 100644
--- a/cipher/ChangeLog
+++ b/cipher/ChangeLog
@@ -1,3 +1,14 @@
+2007-12-05  Werner Koch  <wk@g10code.com>
+
+	* rsa.c (secret): Fixed condition test for using CRT.  Reported by
+	Dean Scarff.  Fixes bug#864.
+	(_gcry_rsa_check_secret_key): Return an erro if the optional
+	parameters are missing.
+	* pubkey.c (sexp_elements_extract): Add arg ALGO_NAME. Changed all
+	callers to pass NULL. Add hack to allow for optional RSA
+	parameters.
+	(sexp_to_key): Pass algo name to sexp_elements_extract.
+
 2007-12-03  Werner Koch  <wk@g10code.com>
 
 	* random.c (gcry_random_add_bytes): Implement it.
diff --git a/cipher/pubkey.c b/cipher/pubkey.c
index 91fbfd4b..fc57b40a 100644
--- a/cipher/pubkey.c
+++ b/cipher/pubkey.c
@@ -751,9 +751,9 @@ pubkey_verify (int algorithm, gcry_mpi_t hash, gcry_mpi_t *data,
 /* Internal function.   */
 static gcry_err_code_t
 sexp_elements_extract (gcry_sexp_t key_sexp, const char *element_names,
-		       gcry_mpi_t *elements)
+		       gcry_mpi_t *elements, const char *algo_name)
 {
-  gcry_err_code_t err = GPG_ERR_NO_ERROR;
+  gcry_err_code_t err = 0;
   int i, idx;
   const char *name;
   gcry_sexp_t list;
@@ -761,17 +761,41 @@ sexp_elements_extract (gcry_sexp_t key_sexp, const char *element_names,
   for (name = element_names, idx = 0; *name && !err; name++, idx++)
     {
       list = gcry_sexp_find_token (key_sexp, name, 1);
-      if (! list)
-	err = GPG_ERR_NO_OBJ;
+      if (!list)
+	elements[idx] = NULL;
       else
 	{
 	  elements[idx] = gcry_sexp_nth_mpi (list, 1, GCRYMPI_FMT_USG);
 	  gcry_sexp_release (list);
-	  if (! elements[idx])
+	  if (!elements[idx])
 	    err = GPG_ERR_INV_OBJ;
 	}
     }
 
+  if (!err)
+    {
+      /* Check that all elements are available.  */
+      for (name = element_names, idx = 0; *name; name++, idx++)
+        if (!elements[idx])
+          break;
+      if (*name)
+        {
+          err = GPG_ERR_NO_OBJ;
+          /* Some are missing.  Before bailing out we test for
+             optional parameters.  */
+          if (algo_name && !strcmp (algo_name, "RSA")
+              && !strcmp (element_names, "nedpqu") )
+            {
+              /* This is RSA.  Test whether we got N, E and D and that
+                 the optional P, Q and U are all missing.  */
+              if (elements[0] && elements[1] && elements[2]
+                  && !elements[3] && !elements[4] && !elements[5])
+                err = 0;
+            }
+        }
+    }
+
+
   if (err)
     {
       for (i = 0; i < idx; i++)
@@ -884,8 +908,6 @@ sexp_elements_extract_ecc (gcry_sexp_t key_sexp, const char *element_names,
  * NOTE: we look through the list to find a list beginning with
  * "private-key" or "public-key" - the first one found is used.
  *
- * FIXME: Allow for encrypted secret keys here.
- *
  * Returns: A pointer to an allocated array of MPIs if the return value is
  *	    zero; the caller has to release this array.
  *
@@ -959,7 +981,7 @@ sexp_to_key (gcry_sexp_t sexp, int want_private, gcry_mpi_t **retarray,
       if (is_ecc)
         err = sexp_elements_extract_ecc (list, elems, array);
       else
-        err = sexp_elements_extract (list, elems, array);
+        err = sexp_elements_extract (list, elems, array, pubkey->name);
     }
   
   gcry_sexp_release (list);
@@ -1048,7 +1070,7 @@ sexp_to_sig (gcry_sexp_t sexp, gcry_mpi_t **retarray,
     err = gpg_err_code_from_errno (errno);
 
   if (!err)
-    err = sexp_elements_extract (list, elems, array);
+    err = sexp_elements_extract (list, elems, array, NULL);
 
   gcry_sexp_release (l2);
   gcry_sexp_release (list);
@@ -1190,7 +1212,7 @@ sexp_to_enc (gcry_sexp_t sexp, gcry_mpi_t **retarray, gcry_module_t *retalgo,
       goto leave;
     }
 
-  err = sexp_elements_extract (list, elems, array);
+  err = sexp_elements_extract (list, elems, array, NULL);
 
  leave:
   gcry_sexp_release (list);
@@ -1921,7 +1943,7 @@ gcry_pk_verify (gcry_sexp_t s_sig, gcry_sexp_t s_hash, gcry_sexp_t s_pkey)
    Test a key.
 
    This may be used either for a public or a secret key to see whether
-   internal structre is valid.
+   the internal structure is okay.
   
    Returns: 0 or an errorcode.
   
diff --git a/cipher/rsa.c b/cipher/rsa.c
index 7d5fd4c0..fe545c7a 100644
--- a/cipher/rsa.c
+++ b/cipher/rsa.c
@@ -1,6 +1,6 @@
 /* rsa.c  -  RSA function
- *	Copyright (C) 1997, 1998, 1999 by Werner Koch (dd9jn)
- *	Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
+ * Copyright (C) 1997, 1998, 1999 by Werner Koch (dd9jn)
+ * Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
  *
  * This file is part of Libgcrypt.
  *
@@ -15,8 +15,7 @@
  * GNU Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
- * License along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
  */
 
 /* This code uses an algorithm protected by U.S. Patent #4,405,829
@@ -357,7 +356,7 @@ stronger_key_check ( RSA_secret_key *skey )
 static void
 secret(gcry_mpi_t output, gcry_mpi_t input, RSA_secret_key *skey )
 {
-  if (!skey->p && !skey->q && !skey->u)
+  if (!skey->p || !skey->q || !skey->u)
     {
       mpi_powm (output, input, skey->d, skey->n);
     }
@@ -488,7 +487,10 @@ _gcry_rsa_check_secret_key( int algo, gcry_mpi_t *skey )
   sk.q = skey[4];
   sk.u = skey[5];
 
-  if (! check_secret_key (&sk))
+  if (!sk.p || !sk.q || !sk.u)
+    err = GPG_ERR_NO_OBJ;  /* To check the key we need the optional
+                              parameters. */
+  else if (!check_secret_key (&sk))
     err = GPG_ERR_PUBKEY_ALGO;
 
   return err;
@@ -529,9 +531,9 @@ _gcry_rsa_decrypt (int algo, gcry_mpi_t *result, gcry_mpi_t *data,
   sk.n = skey[0];
   sk.e = skey[1];
   sk.d = skey[2];
-  sk.p = skey[3];
-  sk.q = skey[4];
-  sk.u = skey[5];
+  sk.p = skey[3]; /* Optional. */
+  sk.q = skey[4]; /* Optional. */
+  sk.u = skey[5]; /* Optional. */
 
   y = gcry_mpi_snew (gcry_mpi_get_nbits (sk.n));