2014-05-08 10:50:30 +00:00
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/*
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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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2014-05-19 20:26:10 +00:00
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#include "pqc_encrypt.h"
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2014-05-08 10:50:30 +00:00
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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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2014-05-19 20:26:10 +00:00
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*
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2014-05-08 10:50:30 +00:00
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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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2014-05-19 20:26:10 +00:00
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*
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2014-05-08 10:50:30 +00:00
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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
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*/
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2014-05-19 20:26:10 +00:00
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void pb_encrypt(ntru_context *ctx,
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2014-05-08 10:50:30 +00:00
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pb_poly *rnd,
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pb_poly *msg,
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pb_poly *pubKey,
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2014-05-19 20:26:10 +00:00
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pb_poly *out)
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2014-05-12 08:33:04 +00:00
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{
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2014-05-08 10:50:30 +00:00
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mp_int *tmpOut;
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mp_int *tmpMsg;
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2014-05-19 20:26:10 +00:00
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mp_int mp_int_mod;
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init_integer(&mp_int_mod);
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MP_SET_INT(&mp_int_mod,(unsigned long)ctx->q);
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2014-05-08 10:50:30 +00:00
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pb_starmultiply(pubKey, rnd, out, ctx, ctx->q);
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2014-05-19 20:26:10 +00:00
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2014-05-08 10:50:30 +00:00
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tmpOut = out->terms;
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tmpMsg = msg->terms;
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2014-05-19 20:26:10 +00:00
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2014-05-08 10:50:30 +00:00
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for(unsigned int i = 0; i <= ctx->N-1; i++) {
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mp_add(tmpOut,tmpMsg,tmpOut);
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2014-05-19 20:26:10 +00:00
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mp_mod(tmpOut,&mp_int_mod,tmpOut);
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2014-05-08 10:50:30 +00:00
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tmpOut++;
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tmpMsg++;
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}
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}
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