Mercurial > trustbridge > nss-cmake-static

annotate nss/lib/freebl/ecl/ec_naf.c @ 4:b513267f632f tip

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Build DBM module
author Andre Heinecke <andre.heinecke@intevation.de>
date Tue, 05 Aug 2014 18:58:03 +0200
parents 1e5118fa0cb1
children
rev   line source
0
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
1 /* This Source Code Form is subject to the terms of the Mozilla Public
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
4
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
5 #include "ecl-priv.h"
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
6
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
7 /* Returns 2^e as an integer. This is meant to be used for small powers of
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
8 * two. */
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
9 int
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
10 ec_twoTo(int e)
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
11 {
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
12 int a = 1;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
13 int i;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
14
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
15 for (i = 0; i < e; i++) {
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
16 a *= 2;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
17 }
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
18 return a;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
19 }
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
20
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
21 /* Computes the windowed non-adjacent-form (NAF) of a scalar. Out should
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
22 * be an array of signed char's to output to, bitsize should be the number
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
23 * of bits of out, in is the original scalar, and w is the window size.
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
24 * NAF is discussed in the paper: D. Hankerson, J. Hernandez and A.
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
25 * Menezes, "Software implementation of elliptic curve cryptography over
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
26 * binary fields", Proc. CHES 2000. */
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
27 mp_err
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
28 ec_compute_wNAF(signed char *out, int bitsize, const mp_int *in, int w)
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
29 {
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
30 mp_int k;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
31 mp_err res = MP_OKAY;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
32 int i, twowm1, mask;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
33
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
34 twowm1 = ec_twoTo(w - 1);
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
35 mask = 2 * twowm1 - 1;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
36
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
37 MP_DIGITS(&k) = 0;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
38 MP_CHECKOK(mp_init_copy(&k, in));
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
39
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
40 i = 0;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
41 /* Compute wNAF form */
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
42 while (mp_cmp_z(&k) > 0) {
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
43 if (mp_isodd(&k)) {
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
44 out[i] = MP_DIGIT(&k, 0) & mask;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
45 if (out[i] >= twowm1)
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
46 out[i] -= 2 * twowm1;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
47
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
48 /* Subtract off out[i]. Note mp_sub_d only works with
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
49 * unsigned digits */
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
50 if (out[i] >= 0) {
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
51 mp_sub_d(&k, out[i], &k);
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
52 } else {
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
53 mp_add_d(&k, -(out[i]), &k);
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
54 }
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
55 } else {
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
56 out[i] = 0;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
57 }
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
58 mp_div_2(&k, &k);
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
59 i++;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
60 }
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
61 /* Zero out the remaining elements of the out array. */
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
62 for (; i < bitsize + 1; i++) {
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
63 out[i] = 0;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
64 }
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
65 CLEANUP:
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
66 mp_clear(&k);
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
67 return res;
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
68
1e5118fa0cb1 This is NSS with a Cmake Buildsyste
Andre Heinecke <andre.heinecke@intevation.de>
parents:
diff changeset
69 }
This site is hosted by Intevation GmbH (Datenschutzerklärung und Impressum | Privacy Policy and Imprint)