diff libtommath/bn_mp_rand.c @ 284:eed26cff980b

propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583) to branch 'au.asn.ucc.matt.dropbear' (head fff0894a0399405a9410ea1c6d118f342cf2aa64)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:49 +0000
parents
children 5ff8218bcee9
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtommath/bn_mp_rand.c	Wed Mar 08 13:23:49 2006 +0000
@@ -0,0 +1,51 @@
+#include <tommath.h>
+#ifdef BN_MP_RAND_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, [email protected], http://math.libtomcrypt.org
+ */
+
+/* makes a pseudo-random int of a given size */
+int
+mp_rand (mp_int * a, int digits)
+{
+  int     res;
+  mp_digit d;
+
+  mp_zero (a);
+  if (digits <= 0) {
+    return MP_OKAY;
+  }
+
+  /* first place a random non-zero digit */
+  do {
+    d = ((mp_digit) abs (rand ())) & MP_MASK;
+  } while (d == 0);
+
+  if ((res = mp_add_d (a, d, a)) != MP_OKAY) {
+    return res;
+  }
+
+  while (--digits > 0) {
+    if ((res = mp_lshd (a, 1)) != MP_OKAY) {
+      return res;
+    }
+
+    if ((res = mp_add_d (a, ((mp_digit) abs (rand ())), a)) != MP_OKAY) {
+      return res;
+    }
+  }
+
+  return MP_OKAY;
+}
+#endif