propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3)

            to branch 'au.asn.ucc.matt.dropbear' (head fdf4a7a3b97ae5046139915de7e40399cceb2c01)

--HG--
extra : convert_revision : dc4809882e1b9f2dcd3f8bbe38c74a0a52c39ce4

1 files changed, 62 insertions, 0 deletions

diff --git a/libtommath/bn_mp_mul.c b/libtommath/bn_mp_mul.c
new file mode 100644
index 0000000..f9cfa09
--- /dev/null
+++ b/libtommath/bn_mp_mul.c
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+#include <tommath.h>
+#ifdef BN_MP_MUL_C
+/* LibTomMath, multiple-precision integer library -- Tom St Denis
+ *
+ * LibTomMath is a library that provides multiple-precision
+ * integer arithmetic as well as number theoretic functionality.
+ *
+ * The library was designed directly after the MPI library by
+ * Michael Fromberger but has been written from scratch with
+ * additional optimizations in place.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ *
+ * Tom St Denis, tomstdenis@iahu.ca, http://math.libtomcrypt.org
+ */
+
+/* high level multiplication (handles sign) */
+int mp_mul (mp_int * a, mp_int * b, mp_int * c)
+{
+  int     res, neg;
+  neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
+
+  /* use Toom-Cook? */
+#ifdef BN_MP_TOOM_MUL_C
+  if (MIN (a->used, b->used) >= TOOM_MUL_CUTOFF) {
+    res = mp_toom_mul(a, b, c);
+  } else 
+#endif
+#ifdef BN_MP_KARATSUBA_MUL_C
+  /* use Karatsuba? */
+  if (MIN (a->used, b->used) >= KARATSUBA_MUL_CUTOFF) {
+    res = mp_karatsuba_mul (a, b, c);
+  } else 
+#endif
+  {
+    /* can we use the fast multiplier?
+     *
+     * The fast multiplier can be used if the output will 
+     * have less than MP_WARRAY digits and the number of 
+     * digits won't affect carry propagation
+     */
+    int     digs = a->used + b->used + 1;
+
+#ifdef BN_FAST_S_MP_MUL_DIGS_C
+    if ((digs < MP_WARRAY) &&
+        MIN(a->used, b->used) <= 
+        (1 << ((CHAR_BIT * sizeof (mp_word)) - (2 * DIGIT_BIT)))) {
+      res = fast_s_mp_mul_digs (a, b, c, digs);
+    } else 
+#endif
+#ifdef BN_S_MP_MUL_DIGS_C
+      res = s_mp_mul (a, b, c); /* uses s_mp_mul_digs */
+#else
+      res = MP_VAL;
+#endif
+
+  }
+  c->sign = (c->used > 0) ? neg : MP_ZPOS;
+  return res;
+}
+#endif