auth.c

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/*
 * auth.c
 *
 * some bookkeeping functions for authentication functions
 *
 * David A. McGrew
 * Cisco Systems, Inc.
 */

/*
 *	
 * Copyright (c) 2001-2005, Cisco Systems, Inc.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted 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 the Cisco Systems, Inc. nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 * 
 * 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 HOLDERS 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.
 *
 */

#include "auth.h"

/* the debug module for authentiation */

debug_module_t mod_auth = {
  0,                  /* debugging is off by default */
  "auth func"         /* printable name for module   */
};


int
auth_get_key_length(const auth_t *a) {
  return a->key_len;
}

int
auth_get_tag_length(const auth_t *a) {
  return a->out_len;
}

int
auth_get_prefix_length(const auth_t *a) {
  return a->prefix_len;
}

int
auth_type_get_ref_count(const auth_type_t *at) {
  return at->ref_count;
}

/*
 * auth_type_self_test() tests an auth function of type ct against
 * test cases provided in an array of values of key, data, and tag
 * that is known to be good
 */

/* should be big enough for most occasions */
#define SELF_TEST_TAG_BUF_OCTETS 32

err_status_t
auth_type_self_test(const auth_type_t *at) {
  auth_test_case_t *test_case = at->test_data;
  auth_t *a;
  err_status_t status;
  uint8_t tag[SELF_TEST_TAG_BUF_OCTETS];
  int i, case_num = 0;

  debug_print(mod_auth, "running self-test for auth function %s", 
	      at->description);
  
  /*
   * check to make sure that we have at least one test case, and
   * return an error if we don't - we need to be paranoid here
   */
  if (test_case == NULL)
    return err_status_cant_check;

  /* loop over all test cases */  
  while (test_case != NULL) {

    /* check test case parameters */
    if (test_case->tag_length_octets > SELF_TEST_TAG_BUF_OCTETS)
      return err_status_bad_param;
    
    /* allocate auth */
    status = auth_type_alloc(at, &a, test_case->key_length_octets,
			     test_case->tag_length_octets);
    if (status)
      return status;
    
    /* initialize auth */
    status = auth_init(a, test_case->key);
    if (status) {
      auth_dealloc(a);
      return status;
    }

    /* zeroize tag then compute */
    octet_string_set_to_zero(tag, test_case->tag_length_octets);
    status = auth_compute(a, test_case->data,
			  test_case->data_length_octets, tag);
    if (status) {
      auth_dealloc(a);
      return status;
    }
    
    debug_print(mod_auth, "key: %s",
		octet_string_hex_string(test_case->key,
					test_case->key_length_octets));
    debug_print(mod_auth, "data: %s",
		octet_string_hex_string(test_case->data,
				   test_case->data_length_octets));
    debug_print(mod_auth, "tag computed: %s",
	   octet_string_hex_string(tag, test_case->tag_length_octets));
    debug_print(mod_auth, "tag expected: %s",
	   octet_string_hex_string(test_case->tag,
				   test_case->tag_length_octets));

    /* check the result */
    status = err_status_ok;
    for (i=0; i < test_case->tag_length_octets; i++)
      if (tag[i] != test_case->tag[i]) {
	status = err_status_algo_fail;
	debug_print(mod_auth, "test case %d failed", case_num);
	debug_print(mod_auth, "  (mismatch at octet %d)", i);
      }
    if (status) {
      auth_dealloc(a);
      return err_status_algo_fail;
    }
    
    /* deallocate the auth function */
    status = auth_dealloc(a);
    if (status)
      return status;
    
    /* 
     * the auth function passed the test case, so move on to the next test
     * case in the list; if NULL, we'll quit and return an OK
     */   
    test_case = test_case->next_test_case;
    ++case_num;
  }
  
  return err_status_ok;
}