src/libstrongswan/plugins/ntru/ntru_public_key.c

   1 /*
   2  * Copyright (C) 2014 Andreas Steffen
   3  * HSR Hochschule fuer Technik Rapperswil
   4  *
   5  * Copyright (C) 2009-2013  Security Innovation
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the
   9  * Free Software Foundation; either version 2 of the License, or (at your
  10  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15  * for more details.
  16  */
  17
  18 #include "ntru_public_key.h"
  19
  20 #include "ntru_crypto/ntru_crypto_ntru_convert.h"
  21
  22 #include <utils/debug.h>
  23
  24 typedef struct private_ntru_public_key_t private_ntru_public_key_t;
  25
  26 /**
  27  * Private data of an ntru_public_key_t object.
  28  */
  29 struct private_ntru_public_key_t {
  30         /**
  31          * Public ntru_public_key_t interface.
  32          */
  33         ntru_public_key_t public;
  34
  35         /**
  36          * NTRU Parameter Set
  37          */
  38         ntru_param_set_t *params;
  39
  40         /**
  41          * Polynomial h which is the public key
  42          */
  43         uint16_t *pubkey;
  44
  45         /**
  46          * Encoding of the public key
  47          */
  48         chunk_t encoding;
  49
  50 };
  51
  52 METHOD(ntru_public_key_t, get_encoding, chunk_t,
  53         private_ntru_public_key_t *this)
  54 {
  55         if (!this->encoding.len)
  56         {
  57                 size_t pubkey_len;
  58                 u_char *enc;
  59
  60                 /* compute public key length encoded as packed coefficients */
  61                 pubkey_len =  (this->params->N * this->params->q_bits + 7) / 8;
  62
  63                 /* allocate memory for public key encoding */
  64                 this->encoding = chunk_alloc(2 + NTRU_OID_LEN + pubkey_len);
  65                 enc = this->encoding.ptr;
  66
  67                 /* format header and packed public key */
  68                 *enc++ = NTRU_PUBKEY_TAG;
  69                 *enc++ = NTRU_OID_LEN;
  70                 memcpy(enc, this->params->oid, NTRU_OID_LEN);
  71                 enc += NTRU_OID_LEN;
  72                 ntru_elements_2_octets(this->params->N, this->pubkey,
  73                                                            this->params->q_bits, enc);
  74         }
  75         return this->encoding;
  76 }
  77
  78 METHOD(ntru_public_key_t, destroy, void,
  79         private_ntru_public_key_t *this)
  80 {
  81         chunk_clear(&this->encoding);
  82         free(this->pubkey);
  83         free(this);
  84 }
  85
  86 /*
  87  * Described in header.
  88  */
  89 ntru_public_key_t *ntru_public_key_create(ntru_param_set_t *params,
  90                                                                                   uint16_t *pubkey)
  91 {
  92         private_ntru_public_key_t *this;
  93         int i;
  94
  95         INIT(this,
  96                 .public = {
  97                         .get_encoding = _get_encoding,
  98                         .destroy = _destroy,
  99                 },
 100                 .params = params,
 101                 .pubkey = malloc(params->N * sizeof(uint16_t)),
 102         );
 103
 104         for (i = 0; i < params->N; i++)
 105         {
 106                 this->pubkey[i] = pubkey[i];
 107         }
 108
 109         return &this->public;
 110 }