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       1                 :             : /*
       2                 :             :    Copyright (c) 2021 Fraunhofer AISEC. See the COPYRIGHT
       3                 :             :    file at the top-level directory of this distribution.
       4                 :             : 
       5                 :             :    Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
       6                 :             :    http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
       7                 :             :    <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
       8                 :             :    option. This file may not be copied, modified, or distributed
       9                 :             :    except according to those terms.
      10                 :             : */
      11                 :             : 
      12                 :             : #include <stdio.h>
      13                 :             : #include <string.h>
      14                 :             : 
      15                 :             : #include "oscore/nonce.h"
      16                 :             : #include "oscore/security_context.h"
      17                 :             : 
      18                 :             : #include "common/print_util.h"
      19                 :             : #include "common/memcpy_s.h"
      20                 :             : 
      21                 :          24 : enum err create_nonce(struct byte_array *id_piv, struct byte_array *piv,
      22                 :             :                       struct byte_array *common_iv, struct byte_array *nonce)
      23                 :             : {
      24                 :             :         /* "1. left-padding the PIV in network byte order with zeroes to exactly 5 bytes"*/
      25                 :          24 :         uint8_t padded_piv[MAX_PIV_LEN] = { 0 };
      26         [ -  + ]:          24 :         TRY(_memcpy_s(&padded_piv[sizeof(padded_piv) - piv->len], piv->len,
      27                 :             :                       piv->ptr, piv->len));
      28                 :             : 
      29                 :             :         /* "2. left-padding the ID_PIV in network byte order with zeroes to exactly nonce length minus 6 bytes," */
      30                 :             : 
      31                 :          24 :         uint8_t padded_id_piv[NONCE_LEN - MAX_PIV_LEN - 1] = { 0 };
      32                 :          24 :         const uint8_t padded_id_piv_len = sizeof(padded_id_piv);
      33         [ -  + ]:          24 :         TRY(_memcpy_s(&padded_id_piv[sizeof(padded_id_piv) - id_piv->len],
      34                 :             :                       id_piv->len, id_piv->ptr, id_piv->len));
      35                 :             : 
      36                 :             :         /* "3. concatenating the size of the ID_PIV (a single byte S) with the padded ID_PIV and the padded PIV,"*/
      37                 :          24 :         nonce->ptr[0] = (uint8_t)id_piv->len;
      38         [ -  + ]:          24 :         TRY(_memcpy_s(&nonce->ptr[1], padded_id_piv_len, padded_id_piv,
      39                 :             :                       padded_id_piv_len));
      40                 :             : 
      41         [ -  + ]:          24 :         TRY(_memcpy_s(&nonce->ptr[1 + sizeof(padded_id_piv)],
      42                 :             :                       sizeof(padded_piv), padded_piv, sizeof(padded_piv)));
      43                 :             : 
      44                 :          24 :         PRINT_ARRAY("nonce input A", nonce->ptr, nonce->len);
      45                 :          24 :         PRINT_ARRAY("nonce input B", common_iv->ptr, common_iv->len);
      46                 :             :         /* "4. and then XORing with the Common IV."*/
      47         [ +  + ]:         336 :         for (uint32_t i = 0; i < common_iv->len; i++) {
      48                 :         312 :                 nonce->ptr[i] ^= common_iv->ptr[i];
      49                 :             :         }
      50                 :             : 
      51                 :          24 :         PRINT_ARRAY("nonce", nonce->ptr, nonce->len);
      52                 :          24 :         return ok;
      53                 :             : }