The Tor Browser / file revision

 /*

  * hmac.c

  *

  * implementation of hmac auth_type_t

  *

  * David A. McGrew

  * Cisco Systems, Inc.

  */

 /*

  *	

  * Copyright(c) 2001-2006 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 "hmac.h" 

 #include "alloc.h"

 /* the debug module for authentiation */

 debug_module_t mod_hmac = {

   0,                  /* debugging is off by default */

   "hmac sha-1"        /* printable name for module   */

 };

 err_status_t

 hmac_alloc(auth_t **a, int key_len, int out_len) {

   extern auth_type_t hmac;

   uint8_t *pointer;

   debug_print(mod_hmac, "allocating auth func with key length %d", key_len);

   debug_print(mod_hmac, "                          tag length %d", out_len);

   /*

    * check key length - note that we don't support keys larger

    * than 20 bytes yet

    */

   if (key_len > 20)

     return err_status_bad_param;

   /* check output length - should be less than 20 bytes */

   if (out_len > 20)

     return err_status_bad_param;

   /* allocate memory for auth and hmac_ctx_t structures */

   pointer = (uint8_t*)crypto_alloc(sizeof(hmac_ctx_t) + sizeof(auth_t));

   if (pointer == NULL)

     return err_status_alloc_fail;

   /* set pointers */

   *a = (auth_t *)pointer;

   (*a)->type = &hmac;

   (*a)->state = pointer + sizeof(auth_t);  

   (*a)->out_len = out_len;

   (*a)->key_len = key_len;

   (*a)->prefix_len = 0;

   /* increment global count of all hmac uses */

   hmac.ref_count++;

   return err_status_ok;

 }

 err_status_t

 hmac_dealloc(auth_t *a) {

   extern auth_type_t hmac;

   /* zeroize entire state*/

   octet_string_set_to_zero((uint8_t *)a, 

 			   sizeof(hmac_ctx_t) + sizeof(auth_t));

   /* free memory */

   crypto_free(a);

   /* decrement global count of all hmac uses */

   hmac.ref_count--;

   return err_status_ok;

 }

 err_status_t

 hmac_init(hmac_ctx_t *state, const uint8_t *key, int key_len) {

   int i;

   uint8_t ipad[64]; 

     /*

    * check key length - note that we don't support keys larger

    * than 20 bytes yet

    */

   if (key_len > 20)              

     return err_status_bad_param;

   /*

    * set values of ipad and opad by exoring the key into the

    * appropriate constant values

    */

   for (i=0; i < key_len; i++) {    

     ipad[i] = key[i] ^ 0x36;

     state->opad[i] = key[i] ^ 0x5c;

   }  

   /* set the rest of ipad, opad to constant values */

   for (   ; i < 64; i++) {    

     ipad[i] = 0x36;

     ((uint8_t *)state->opad)[i] = 0x5c;

   }  

   debug_print(mod_hmac, "ipad: %s", octet_string_hex_string(ipad, 64));

   /* initialize sha1 context */

   sha1_init(&state->init_ctx);

   /* hash ipad ^ key */

   sha1_update(&state->init_ctx, ipad, 64);

   memcpy(&state->ctx, &state->init_ctx, sizeof(sha1_ctx_t)); 

   return err_status_ok;

 }

 err_status_t

 hmac_start(hmac_ctx_t *state) {

   memcpy(&state->ctx, &state->init_ctx, sizeof(sha1_ctx_t));

   return err_status_ok;

 }

 err_status_t

 hmac_update(hmac_ctx_t *state, const uint8_t *message, int msg_octets) {

   debug_print(mod_hmac, "input: %s", 

 	      octet_string_hex_string(message, msg_octets));

   /* hash message into sha1 context */

   sha1_update(&state->ctx, message, msg_octets);

   return err_status_ok;

 }

 err_status_t

 hmac_compute(hmac_ctx_t *state, const void *message,

 	     int msg_octets, int tag_len, uint8_t *result) {

   uint32_t hash_value[5];

   uint32_t H[5];

   int i;

   /* check tag length, return error if we can't provide the value expected */

   if (tag_len > 20)

     return err_status_bad_param;

   /* hash message, copy output into H */

   hmac_update(state, (const uint8_t*)message, msg_octets);

   sha1_final(&state->ctx, H);

   /*

    * note that we don't need to debug_print() the input, since the

    * function hmac_update() already did that for us

    */

   debug_print(mod_hmac, "intermediate state: %s", 

 	      octet_string_hex_string((uint8_t *)H, 20));

   /* re-initialize hash context */

   sha1_init(&state->ctx);

   /* hash opad ^ key  */

   sha1_update(&state->ctx, (uint8_t *)state->opad, 64);

   /* hash the result of the inner hash */

   sha1_update(&state->ctx, (uint8_t *)H, 20);

   /* the result is returned in the array hash_value[] */

   sha1_final(&state->ctx, hash_value);

   /* copy hash_value to *result */

   for (i=0; i < tag_len; i++)    

     result[i] = ((uint8_t *)hash_value)[i];

   debug_print(mod_hmac, "output: %s", 

 	      octet_string_hex_string((uint8_t *)hash_value, tag_len));

   return err_status_ok;

 }

 /* begin test case 0 */

 uint8_t

 hmac_test_case_0_key[20] = {

   0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 

   0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 

   0x0b, 0x0b, 0x0b, 0x0b

 };

 uint8_t 

 hmac_test_case_0_data[8] = {

   0x48, 0x69, 0x20, 0x54, 0x68, 0x65, 0x72, 0x65   /* "Hi There" */

 };

 uint8_t

 hmac_test_case_0_tag[20] = {

   0xb6, 0x17, 0x31, 0x86, 0x55, 0x05, 0x72, 0x64, 

   0xe2, 0x8b, 0xc0, 0xb6, 0xfb, 0x37, 0x8c, 0x8e, 

   0xf1, 0x46, 0xbe, 0x00

 };

 auth_test_case_t

 hmac_test_case_0 = {

   20,                        /* octets in key            */

   hmac_test_case_0_key,      /* key                      */

   8,                         /* octets in data           */ 

   hmac_test_case_0_data,     /* data                     */

   20,                        /* octets in tag            */

   hmac_test_case_0_tag,      /* tag                      */

   NULL                       /* pointer to next testcase */

 };

 /* end test case 0 */

 char hmac_description[] = "hmac sha-1 authentication function";

 /*

  * auth_type_t hmac is the hmac metaobject

  */

 auth_type_t

 hmac  = {

   (auth_alloc_func)      hmac_alloc,

   (auth_dealloc_func)    hmac_dealloc,

   (auth_init_func)       hmac_init,

   (auth_compute_func)    hmac_compute,

   (auth_update_func)     hmac_update,

   (auth_start_func)      hmac_start,

   (char *)               hmac_description,

   (int)                  0,  /* instance count */

   (auth_test_case_t *)  &hmac_test_case_0,

   (debug_module_t *)    &mod_hmac,

   (auth_type_id_t)       HMAC_SHA1

 };