57 lines
1.7 KiB
C
57 lines
1.7 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 "decrypt.h"
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#include <fmpz_poly.h>
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#include <fmpz.h>
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/**
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* Decryption of the given Polynom with the private key, its inverse
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* and the fitting ntru_context
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*
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* @param encr_msg encrypted polynom with maximum length of N from
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* the given context
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* @param priv_key the polynom containing the private key to decrypt
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* the message
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* @param priv_key_inv the inverse polynome to the private key
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* @param context the ntru_context
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* @param out the result polynom is written in here [out]
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*
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*/
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void ntru_decrypt_poly(
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fmpz_poly_t encr_msg,
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fmpz_poly_t priv_key,
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fmpz_poly_t priv_key_inv,
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fmpz_poly_t out,
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ntru_context *ctx)
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{
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fmpz_poly_t a;
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fmpz_poly_init(a);
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fmpz_poly_zero(a);
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poly_starmultiply(priv_key, encr_msg, a, ctx, ctx->q);
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fmpz_poly_mod(a, ctx->q);
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poly_starmultiply(a, priv_key_inv, out, ctx, ctx->p);
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}
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