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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
commit | 26a029d407be480d791972afb5975cf62c9360a6 (patch) | |
tree | f435a8308119effd964b339f76abb83a57c29483 /security/nss/lib/freebl/ecl/ec_naf.c | |
parent | Initial commit. (diff) | |
download | firefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz firefox-26a029d407be480d791972afb5975cf62c9360a6.zip |
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'security/nss/lib/freebl/ecl/ec_naf.c')
-rw-r--r-- | security/nss/lib/freebl/ecl/ec_naf.c | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/security/nss/lib/freebl/ecl/ec_naf.c b/security/nss/lib/freebl/ecl/ec_naf.c new file mode 100644 index 0000000000..cad08cb278 --- /dev/null +++ b/security/nss/lib/freebl/ecl/ec_naf.c @@ -0,0 +1,68 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#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_CHECKOK(mp_sub_d(&k, out[i], &k)); + } else { + MP_CHECKOK(mp_add_d(&k, -(out[i]), &k)); + } + } else { + out[i] = 0; + } + MP_CHECKOK(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; +} |