--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/native/sun/security/ec/impl/ec_naf.c	Mon Sep 21 23:01:42 2009 +0100
@@ -0,0 +1,123 @@
+/* *********************************************************************
+ *
+ * Sun elects to have this file available under and governed by the
+ * Mozilla Public License Version 1.1 ("MPL") (see
+ * http://www.mozilla.org/MPL/ for full license text). For the avoidance
+ * of doubt and subject to the following, Sun also elects to allow
+ * licensees to use this file under the MPL, the GNU General Public
+ * License version 2 only or the Lesser General Public License version
+ * 2.1 only. Any references to the "GNU General Public License version 2
+ * or later" or "GPL" in the following shall be construed to mean the
+ * GNU General Public License version 2 only. Any references to the "GNU
+ * Lesser General Public License version 2.1 or later" or "LGPL" in the
+ * following shall be construed to mean the GNU Lesser General Public
+ * License version 2.1 only. However, the following notice accompanied
+ * the original version of this file:
+ *
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is the elliptic curve math library.
+ *
+ * The Initial Developer of the Original Code is
+ * Sun Microsystems, Inc.
+ * Portions created by the Initial Developer are Copyright (C) 2003
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Stephen Fung <fungstep@hotmail.com>, Sun Microsystems Laboratories
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ *********************************************************************** */
+/*
+ * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#pragma ident   "%Z%%M% %I%     %E% SMI"
+
+#include "ecl-priv.h"
+
+/* Returns 2^e as an integer. This is meant to be used for small powers of
+ * two. */
+int
+ec_twoTo(int e)
+{
+        int a = 1;
+        int i;
+
+        for (i = 0; i < e; i++) {
+                a *= 2;
+        }
+        return a;
+}
+
+/* Computes the windowed non-adjacent-form (NAF) of a scalar. Out should
+ * be an array of signed char's to output to, bitsize should be the number
+ * of bits of out, in is the original scalar, and w is the window size.
+ * NAF is discussed in the paper: D. Hankerson, J. Hernandez and A.
+ * Menezes, "Software implementation of elliptic curve cryptography over
+ * binary fields", Proc. CHES 2000. */
+mp_err
+ec_compute_wNAF(signed char *out, int bitsize, const mp_int *in, int w)
+{
+        mp_int k;
+        mp_err res = MP_OKAY;
+        int i, twowm1, mask;
+
+        twowm1 = ec_twoTo(w - 1);
+        mask = 2 * twowm1 - 1;
+
+        MP_DIGITS(&k) = 0;
+        MP_CHECKOK(mp_init_copy(&k, in));
+
+        i = 0;
+        /* Compute wNAF form */
+        while (mp_cmp_z(&k) > 0) {
+                if (mp_isodd(&k)) {
+                        out[i] = MP_DIGIT(&k, 0) & mask;
+                        if (out[i] >= twowm1)
+                                out[i] -= 2 * twowm1;
+
+                        /* Subtract off out[i].  Note mp_sub_d only works with
+                         * unsigned digits */
+                        if (out[i] >= 0) {
+                                mp_sub_d(&k, out[i], &k);
+                        } else {
+                                mp_add_d(&k, -(out[i]), &k);
+                        }
+                } else {
+                        out[i] = 0;
+                }
+                mp_div_2(&k, &k);
+                i++;
+        }
+        /* Zero out the remaining elements of the out array. */
+        for (; i < bitsize + 1; i++) {
+                out[i] = 0;
+        }
+  CLEANUP:
+        mp_clear(&k);
+        return res;
+
+}