text: /*====================================================================*
   *
   *   Copyright (c) 2013 Qualcomm Atheros, Inc.
   *
   *   All rights reserved.
   *
   *   Redistribution and use in source and binary forms, with or 
   *   without modification, are permitted (subject to the limitations 
   *   in the disclaimer below) provided that the following conditions 
   *   are met:
   *
   *   * Redistributions of source code must retain the above copyright 
   *     notice, this list of conditions and the following disclaimer.
   *
   *   * Redistributions in binary form must reproduce the above 
   *     copyright notice, this list of conditions and the following 
   *     disclaimer in the documentation and/or other materials 
   *     provided with the distribution.
   *
   *   * Neither the name of Qualcomm Atheros nor the names of 
   *     its contributors may be used to endorse or promote products 
   *     derived from this software without specific prior written 
   *     permission.
   *
   *   NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE 
   *   GRANTED BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE 
   *   COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR 
   *   IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
   *   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 
   *   PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER 
   *   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
   *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
   *   NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
   *   LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
   *   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
   *   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 
   *   OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 
   *   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.  
   *
   *--------------------------------------------------------------------*/
  
  /*====================================================================*
   *
   *   void HPAVKeyDAK (uint8_t DAK [], const char * string);
   *
   *   HPAVKey.h
   *
   *   compute the HomePlugAV compliant Device Access Key (DAK) for a
   *   NUL terminated string; return the key in buffer DAK[]; the key
   *   will be HPAVKEY_DAK_LEN bytes as defined in HPAVKey.h;
   *
   *   seed the digest then salt the digest then rehash the digest 999
   *   times per HomePlug AV Specification;
   *
   *
   *   Contributor(s);
   *	Charles Maier <cmaier@qca.qualcomm.com>
   *
   *--------------------------------------------------------------------*/
  
  #ifndef HPAVKEYDAK_SOURCE
  #define HPAVKEYDAK_SOURCE
  
  #include <memory.h>
  
  #include "../key/HPAVKey.h"
  #include "../key/SHA256.h"
  
  void HPAVKeyDAK (uint8_t DAK [], const char * string)
  
  {
  	struct sha256 sha256;
  	uint8_t digest [SHA256_DIGEST_LENGTH];
  	const uint8_t secret [] =
  	{
  		0x08,
  		0x85,
  		0x6D,
  		0xAF,
  		0x7C,
  		0xF5,
  		0x81,
  		0x85
  	};
  	unsigned rehash = 999;
  	SHA256Reset (&sha256);
  	SHA256Write (&sha256, string, strlen (string));
  	SHA256Write (&sha256, secret, sizeof (secret));
  	SHA256Fetch (&sha256, digest);
  	while (rehash--)
  	{
  		SHA256Reset (&sha256);
  		SHA256Write (&sha256, digest, sizeof (digest));
  		SHA256Fetch (&sha256, digest);
  	}
  	memcpy (DAK, digest, HPAVKEY_DAK_LEN);
  	return;
  }
  
  
  #endif
  
  