69 lines
1.9 KiB
C
69 lines
1.9 KiB
C
/*
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* Copyright (C) 2014 FH Bielefeld
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*
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* This file is part of a FH Bielefeld project.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301 USA
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*/
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#include "encrypt.h"
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#include <fmpz_poly.h>
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#include <fmpz.h>
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/**
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* encrypt the msg, using the math:
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* e = (h ∗ r) + m (mod q)
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*
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* e = the encrypted poly
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* h = the public key
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* r = the random poly
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* m = the message poly
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* q = large mod
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*
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* @param ctx ntru_context* the ntru context
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* @param rnd pb_poly* the random poly
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* @param msg pb_poly* the message to encrypt
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* @param pubKey pb_poly* the public key
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* @param out pb_poly* the output poly [out]
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*/
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void ntru_encrypt_poly(fmpz_poly_t rnd,
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fmpz_poly_t msg,
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fmpz_poly_t pub_key,
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fmpz_poly_t out,
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ntru_context *ctx)
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{
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poly_starmultiply(pub_key, rnd, out, ctx, ctx->q);
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fmpz_poly_zero(out);
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for(unsigned int i = 0; i <= ctx->N - 1; i++) {
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fmpz_poly_t tmp_poly;
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fmpz_t tmp_coeff;
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fmpz *e_coeff_i = fmpz_poly_get_coeff_ptr(out, i),
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*m_coeff_i = fmpz_poly_get_coeff_ptr(msg, i);
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fmpz_poly_init(tmp_poly);
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fmpz_init(tmp_coeff);
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fmpz_add_n(tmp_coeff, e_coeff_i, m_coeff_i);
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fmpz_mod_ui(tmp_coeff, tmp_coeff, ctx->q);
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fmpz_poly_set_coeff_fmpz(out, i, tmp_coeff);
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}
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}
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