diff bn_prime_sizes_tab.c @ 145:a96ff234ff19 libtommath

propagate of fc94c38452d9fd684a8e1eb9e3a73120aac0d38f and 3e4de4cbef3d9035a7b2f0c25e9f86e297f9f6d1 from branch 'au.asn.ucc.matt.ltm-orig' to 'au.asn.ucc.matt.ltm-db'
author Matt Johnston <matt@ucc.asn.au>
date Sun, 19 Dec 2004 15:57:19 +0000
parents 22d5cf7d4b1a
children
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/bn_prime_sizes_tab.c	Sun Dec 19 15:57:19 2004 +0000
@@ -0,0 +1,51 @@
+/* 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
+ */
+#include <tommath.h>
+
+/* this table gives the # of rabin miller trials for a prob of failure lower than 2^-96 */
+static const struct {
+   int k, t;
+} sizes[] = {
+{   128,    28 },
+{   256,    16 },
+{   384,    10 },
+{   512,     7 },
+{   640,     6 },
+{   768,     5 },
+{   896,     4 },
+{  1024,     4 },
+{  1152,     3 },
+{  1280,     3 },
+{  1408,     3 },
+{  1536,     3 },
+{  1664,     3 },
+{  1792,     2 } };
+
+/* returns # of RM trials required for a given bit size */
+int mp_prime_rabin_miller_trials(int size)
+{
+   int x;
+
+   for (x = 0; x < (int)(sizeof(sizes)/(sizeof(sizes[0]))); x++) {
+       if (sizes[x].k == size) {
+          return sizes[x].t;
+       } else if (sizes[x].k > size) {
+          return (x == 0) ? sizes[0].t : sizes[x - 1].t;
+       }
+   }
+   return 1;
+}
+
+