/*
 * Copyright (c) 1997-2007  The Stanford SRP Authentication Project
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
 *
 * IN NO EVENT SHALL STANFORD BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
 * INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER
 * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER OR NOT ADVISED OF
 * THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF LIABILITY, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Redistributions in source or binary form must retain an intact copy
 * of this copyright notice.
 */

#ifndef T_SERVER_H
#define T_SERVER_H

#include "t_sha.h"
#include "cstr.h"

#define BLEN 32

struct t_server {
  struct t_num n;
  struct t_num g;
  struct t_num v;
  struct t_num s;

  struct t_num b;
  struct t_num B;

  cstr * ex_data;

  SHA1_CTX oldhash, hash, oldckhash, ckhash;

  unsigned char session_key[SESSION_KEY_LEN];
  unsigned char session_response[RESPONSE_LEN];

  unsigned char nbuf[MAXPARAMLEN], gbuf[MAXPARAMLEN], vbuf[MAXPARAMLEN];
  unsigned char saltbuf[MAXSALTLEN], bbuf[BLEN], Bbuf[MAXPARAMLEN];
};

/*
 * SRP server-side negotiation
 *
 * This code negotiates the server side of an SRP exchange.
 * "t_serveropen" accepts a username (sent by the client), a pointer
 *   to an open password file, and a pointer to an open configuration
 *   file.  The server should then call...
 * "t_servergenexp" will generate a random 256-bit exponent and
 *   raise g (from the configuration file) to that power, returning
 *   the result.  This result should be sent to the client as y(p).
 * "t_serveraddexdata" adds data to be authenticated along with
 *   the rest of the session parameters.  This data is included in
 *   the response hash after the session key.
 * "t_servergetkey" accepts the exponential w(p), which should be
 *   sent by the client, and computes the 256-bit session key.
 *   This data should be saved before the session is closed.
 * "t_serverresponse" computes the session key proof as SHA(w(p), K).
 * "t_serverclose" closes the session and frees its memory.
 *
 * Note that authentication is not performed per se; it is up
 * to either/both sides of the protocol to now verify securely
 * that their session keys agree in order to establish authenticity.
 * One possible way is through "oracle hashing"; one side sends
 * r, the other replies with H(r,K), where H() is a hash function.
 *
 * t_serverresponse and t_serververify now implement a version of
 * the session-key verification described above.
 */
_TYPE( struct t_server * )
  t_serveropen P((const char *));
_TYPE( struct t_server * )
  t_serveropenfromfiles P((const char *, struct t_pw *, struct t_conf *));
_TYPE( struct t_server * )
  t_serveropenraw P((struct t_pwent *, struct t_confent *));
_TYPE( struct t_num * ) t_servergenexp P((struct t_server *));
_TYPE( void ) t_serveraddexdata P((struct t_server *, unsigned char *, int));
_TYPE( unsigned char * ) t_servergetkey P((struct t_server *, struct t_num *));
_TYPE( int ) t_serververify P((struct t_server *, unsigned char *));
_TYPE( unsigned char * ) t_serverresponse P((struct t_server *));
_TYPE( void ) t_serverclose P((struct t_server *));

#endif