www.usr.com/support/gpl/USR9107_release.1.4.tar.gz

[bcm963xx.git] / userapps / opensource / sshd / libtommath / bn_mp_exptmod.c

diff --git a/userapps/opensource/sshd/libtommath/bn_mp_exptmod.c b/userapps/opensource/sshd/libtommath/bn_mp_exptmod.c
index e94e658..7c4e2f8 100755 (executable)
--- a/userapps/opensource/sshd/libtommath/bn_mp_exptmod.c
+++ b/userapps/opensource/sshd/libtommath/bn_mp_exptmod.c
@@ -1,9 +1,11 @@
+#include <tommath.h>
+#ifdef BN_MP_EXPTMOD_C
 /* LibTomMath, multiple-precision integer library -- Tom St Denis
  *
- * LibTomMath is library that provides for multiple-precision
+ * LibTomMath is a library that provides multiple-precision
  * integer arithmetic as well as number theoretic functionality.
  *
- * The library is designed directly after the MPI library by
+ * The library was designed directly after the MPI library by
  * Michael Fromberger but has been written from scratch with
  * additional optimizations in place.
  *
@@ -12,7 +14,6 @@
  *
  * Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org
  */
-#include <tommath.h>
 
 
 /* this is a shell function that calls either the normal or Montgomery
@@ -20,8 +21,7 @@
  * embedded in the normal function but that wasted alot of stack space
  * for nothing (since 99% of the time the Montgomery code would be called)
  */
-int
-mp_exptmod (mp_int * G, mp_int * X, mp_int * P, mp_int * Y)
+int mp_exptmod (mp_int * G, mp_int * X, mp_int * P, mp_int * Y)
 {
   int dr;
 
@@ -32,6 +32,7 @@ mp_exptmod (mp_int * G, mp_int * X, mp_int * P, mp_int * Y)
 
   /* if exponent X is negative we have to recurse */
   if (X->sign == MP_NEG) {
+#ifdef BN_MP_INVMOD_C
      mp_int tmpG, tmpX;
      int err;
 
@@ -58,18 +59,50 @@ mp_exptmod (mp_int * G, mp_int * X, mp_int * P, mp_int * Y)
      err = mp_exptmod(&tmpG, &tmpX, P, Y);
      mp_clear_multi(&tmpG, &tmpX, NULL);
      return err;
+#else 
+     /* no invmod */
+     return MP_VAL;
+#endif
   }
 
+/* modified diminished radix reduction */
+#if defined(BN_MP_REDUCE_IS_2K_L_C) && defined(BN_MP_REDUCE_2K_L_C)
+  if (mp_reduce_is_2k_l(P) == MP_YES) {
+     return s_mp_exptmod(G, X, P, Y, 1);
+  }
+#endif
+
+#ifdef BN_MP_DR_IS_MODULUS_C
+  /* is it a DR modulus? */
   dr = mp_dr_is_modulus(P);
+#else
+  /* default to no */
+  dr = 0;
+#endif
+
+#ifdef BN_MP_REDUCE_IS_2K_C
+  /* if not, is it a unrestricted DR modulus? */
   if (dr == 0) {
      dr = mp_reduce_is_2k(P) << 1;
   }
+#endif
     
-  /* if the modulus is odd or dr != 0 use the fast method */
+  /* if the modulus is odd or dr != 0 use the montgomery method */
+#ifdef BN_MP_EXPTMOD_FAST_C
   if (mp_isodd (P) == 1 || dr !=  0) {
     return mp_exptmod_fast (G, X, P, Y, dr);
   } else {
-    return s_mp_exptmod (G, X, P, Y);
+#endif
+#ifdef BN_S_MP_EXPTMOD_C
+    /* otherwise use the generic Barrett reduction technique */
+    return s_mp_exptmod (G, X, P, Y, 0);
+#else
+    /* no exptmod for evens */
+    return MP_VAL;
+#endif
+#ifdef BN_MP_EXPTMOD_FAST_C
   }
+#endif
 }
 
+#endif