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/* nettle, low-level cryptographics library
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* Copyright (C) 2013 Niels Möller
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* The nettle library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2.1 of the License, or (at your
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* option) any later version.
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* The nettle library is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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* License for more details.
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* You should have received a copy of the GNU Lesser General Public License
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* along with the nettle library; see the file COPYING.LIB. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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/* Development of Nettle's ECC support was funded by the .SE Internet Fund. */
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#include "ecc-internal.h"
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#include "nettle-internal.h"
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zero_p (const struct ecc_curve *ecc,
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for (i = t = 0; i < ecc->size; i++)
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ecdsa_in_range (const struct ecc_curve *ecc,
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const mp_limb_t *xp, mp_limb_t *scratch)
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/* Check if 0 < x < q, with data independent timing. */
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return !zero_p (ecc, xp)
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& (mpn_sub_n (scratch, xp, ecc->q, ecc->size) != 0);
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ecc_modq_random (const struct ecc_curve *ecc, mp_limb_t *xp,
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void *ctx, nettle_random_func *random, mp_limb_t *scratch)
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uint8_t *buf = (uint8_t *) scratch;
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unsigned nbytes = (ecc->bit_size + 7)/8;
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/* The bytes ought to fit in the scratch area, unless we have very
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unusual limb and byte sizes. */
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assert (nbytes <= ecc->size * sizeof (mp_limb_t));
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/* q and p are of the same bitsize. */
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random (ctx, nbytes, buf);
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buf[0] &= 0xff >> (nbytes * 8 - ecc->bit_size);
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mpn_set_base256 (xp, ecc->size, buf, nbytes);
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while (!ecdsa_in_range (ecc, xp, scratch));
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ecc_scalar_random (struct ecc_scalar *x,
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void *random_ctx, nettle_random_func *random)
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TMP_DECL (scratch, mp_limb_t, ECC_MODQ_RANDOM_ITCH (ECC_MAX_SIZE));
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TMP_ALLOC (scratch, ECC_MODQ_RANDOM_ITCH (x->ecc->size));
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ecc_modq_random (x->ecc, x->p, random_ctx, random, scratch);