Handle opaque MPIs in gcry_mpi_cmp

2 files changed, 42 insertions, 21 deletions

diff --git a/mpi/ChangeLog b/mpi/ChangeLog
index fb6ea33d..2bf3f2bf 100644
--- a/mpi/ChangeLog
+++ b/mpi/ChangeLog
@@ -1,3 +1,7 @@
+2011-02-01  Werner Koch  <wk@g10code.com>
+
+	* mpi-cmp.c (gcry_mpi_cmp): Allow comparing of opaque MPIs.
+
 2010-04-12  Brad Hards  <bradh@frogmouth.net>  (wk)
 
 	Spelling fixes.
diff --git a/mpi/mpi-cmp.c b/mpi/mpi-cmp.c
index 9dd10830..30e1fce9 100644
--- a/mpi/mpi-cmp.c
+++ b/mpi/mpi-cmp.c
@@ -53,6 +53,7 @@ gcry_mpi_cmp_ui (gcry_mpi_t u, unsigned long v)
     return 1;
 }
 
+
 int
 gcry_mpi_cmp (gcry_mpi_t u, gcry_mpi_t v)
 {
@@ -60,31 +61,47 @@ gcry_mpi_cmp (gcry_mpi_t u, gcry_mpi_t v)
   mpi_size_t vsize;
   int cmp;
 
-  _gcry_mpi_normalize (u);
-  _gcry_mpi_normalize (v);
-
-  usize = u->nlimbs;
-  vsize = v->nlimbs;
+  if (mpi_is_opaque (u) || mpi_is_opaque (v))
+    {
+      if (mpi_is_opaque (u) && !mpi_is_opaque (v))
+        return -1;
+      if (!mpi_is_opaque (u) && mpi_is_opaque (v))
+        return 1;
+      if (!u->sign && !v->sign)
+        return 0; /* Empty buffers are identical.  */
+      if (u->sign < v->sign)
+        return -1;
+      if (u->sign > v->sign)
+        return 1;
+      return memcmp (u->d, v->d, (u->sign+7)/8);
+    }
+  else
+    {
+      _gcry_mpi_normalize (u);
+      _gcry_mpi_normalize (v);
 
-  /* Compare sign bits.  */
+      usize = u->nlimbs;
+      vsize = v->nlimbs;
 
-  if (!u->sign && v->sign)
-    return 1;
-  if (u->sign && !v->sign)
-    return -1;
+      /* Compare sign bits.  */
 
-  /* U and V are either both positive or both negative.  */
+      if (!u->sign && v->sign)
+        return 1;
+      if (u->sign && !v->sign)
+        return -1;
 
-  if( usize != vsize && !u->sign && !v->sign )
-    return usize - vsize;
-  if( usize != vsize && u->sign && v->sign )
-    return vsize + usize;
-  if( !usize )
-    return 0;
-  if( !(cmp = _gcry_mpih_cmp( u->d, v->d, usize )) )
-    return 0;
-  if( (cmp < 0?1:0) == (u->sign?1:0))
-    return 1;
+      /* U and V are either both positive or both negative.  */
 
+      if (usize != vsize && !u->sign && !v->sign)
+        return usize - vsize;
+      if (usize != vsize && u->sign && v->sign)
+        return vsize + usize;
+      if (!usize )
+        return 0;
+      if (!(cmp = _gcry_mpih_cmp (u->d, v->d, usize)))
+        return 0;
+      if ((cmp < 0?1:0) == (u->sign?1:0))
+        return 1;
+    }
   return -1;
 }