The Tor Browser: netwerk/srtp/src/crypto/cipher/aes

netwerk/srtp/src/crypto/cipher/aes_icm.c@6474c204b198 (annotated)

netwerk/srtp/src/crypto/cipher/aes_icm.c

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /*
  * aes_icm.c
  *
  * AES Integer Counter Mode
  *
  * 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.
  *
  */
 #define ALIGN_32 0
 #include "aes_icm.h"
 #include "alloc.h"
 debug_module_t mod_aes_icm = {
 ,                 /* debugging is off by default */
   "aes icm"          /* printable module name       */
 };
 /*
  * integer counter mode works as follows:
  *
  * 16 bits
  * <----->
  * +------+------+------+------+------+------+------+------+
  * |           nonce           |    pakcet index    |  ctr |---+
  * +------+------+------+------+------+------+------+------+   |
  *                                                             |
  * +------+------+------+------+------+------+------+------+   v
  * |                      salt                      |000000|->(+)
  * +------+------+------+------+------+------+------+------+   |
  *                                                             |
  *                                                        +---------+
  *							  | encrypt |
  *							  +---------+
  *							       |
  * +------+------+------+------+------+------+------+------+   |
  * |                    keystream block                    |<--+
  * +------+------+------+------+------+------+------+------+
  *
  * All fields are big-endian
  *
  * ctr is the block counter, which increments from zero for
  * each packet (16 bits wide)
  *
  * packet index is distinct for each packet (48 bits wide)
  *
  * nonce can be distinct across many uses of the same key, or
  * can be a fixed value per key, or can be per-packet randomness
  * (64 bits)
  *
  */
 err_status_t
 aes_icm_alloc_ismacryp(cipher_t **c, int key_len, int forIsmacryp) {
   extern cipher_type_t aes_icm;
   uint8_t *pointer;
   int tmp;
   debug_print(mod_aes_icm,
             "allocating cipher with key length %d", key_len);
   /*
    * Ismacryp, for example, uses 16 byte key + 8 byte
    * salt  so this function is called with key_len = 24.
    * The check for key_len = 30/38/46 does not apply. Our usage
    * of aes functions with key_len = values other than 30
    * has not broken anything. Don't know what would be the
    * effect of skipping this check for srtp in general.
    */
   if (!(forIsmacryp && key_len > 16 && key_len < 30) &&
       key_len != 30 && key_len != 38 && key_len != 46)
     return err_status_bad_param;
   /* allocate memory a cipher of type aes_icm */
   tmp = (sizeof(aes_icm_ctx_t) + sizeof(cipher_t));
   pointer = (uint8_t*)crypto_alloc(tmp);
   if (pointer == NULL)
     return err_status_alloc_fail;
   /* set pointers */
   *c = (cipher_t *)pointer;
   (*c)->type = &aes_icm;
   (*c)->state = pointer + sizeof(cipher_t);
   /* increment ref_count */
   aes_icm.ref_count++;
   /* set key size        */
   (*c)->key_len = key_len;
   return err_status_ok;
 }
 err_status_t aes_icm_alloc(cipher_t **c, int key_len, int forIsmacryp) {
   return aes_icm_alloc_ismacryp(c, key_len, 0);
 }
 err_status_t
 aes_icm_dealloc(cipher_t *c) {
   extern cipher_type_t aes_icm;
   /* zeroize entire state*/
   octet_string_set_to_zero((uint8_t *)c,
 			   sizeof(aes_icm_ctx_t) + sizeof(cipher_t));
   /* free memory */
   crypto_free(c);
   /* decrement ref_count */
   aes_icm.ref_count--;
   return err_status_ok;
 }
 /*
  * aes_icm_context_init(...) initializes the aes_icm_context
  * using the value in key[].
  *
  * the key is the secret key
  *
  * the salt is unpredictable (but not necessarily secret) data which
  * randomizes the starting point in the keystream
  */
 err_status_t
 aes_icm_context_init(aes_icm_ctx_t *c, const uint8_t *key, int key_len) {
   err_status_t status;
   int base_key_len, copy_len;
   if (key_len > 16 && key_len < 30) /* Ismacryp */
     base_key_len = 16;
   else if (key_len == 30 || key_len == 38 || key_len == 46)
     base_key_len = key_len - 14;
   else
     return err_status_bad_param;
   /*
    * set counter and initial values to 'offset' value, being careful not to
    * go past the end of the key buffer
    */
   v128_set_to_zero(&c->counter);
   v128_set_to_zero(&c->offset);
   copy_len = key_len - base_key_len;
   /* force last two octets of the offset to be left zero (for srtp compatibility) */
   if (copy_len > 14)
     copy_len = 14;
   memcpy(&c->counter, key + base_key_len, copy_len);
   memcpy(&c->offset, key + base_key_len, copy_len);
   debug_print(mod_aes_icm,
 	      "key:  %s", octet_string_hex_string(key, base_key_len));
   debug_print(mod_aes_icm,
 	      "offset: %s", v128_hex_string(&c->offset));
   /* expand key */
   status = aes_expand_encryption_key(key, base_key_len, &c->expanded_key);
   if (status) {
     v128_set_to_zero(&c->counter);
     v128_set_to_zero(&c->offset);
     return status;
   }
   /* indicate that the keystream_buffer is empty */
   c->bytes_in_buffer = 0;
   return err_status_ok;
 }
 /*
  * aes_icm_set_octet(c, i) sets the counter of the context which it is
  * passed so that the next octet of keystream that will be generated
  * is the ith octet
  */
 err_status_t
 aes_icm_set_octet(aes_icm_ctx_t *c,
 		  uint64_t octet_num) {
 #ifdef NO_64BIT_MATH
   int tail_num       = low32(octet_num) & 0x0f;
   /* 64-bit right-shift 4 */
   uint64_t block_num = make64(high32(octet_num) >> 4,
 							  ((high32(octet_num) & 0x0f)<<(32-4)) |
 							   (low32(octet_num) >> 4));
 #else
   int tail_num       = (int)(octet_num % 16);
   uint64_t block_num = octet_num / 16;
 #endif
   /* set counter value */
   /* FIX - There's no way this is correct */
   c->counter.v64[0] = c->offset.v64[0];
 #ifdef NO_64BIT_MATH
   c->counter.v64[0] = make64(high32(c->offset.v64[0]) ^ high32(block_num),
 							 low32(c->offset.v64[0])  ^ low32(block_num));
 #else
   c->counter.v64[0] = c->offset.v64[0] ^ block_num;
 #endif
   debug_print(mod_aes_icm,
 	      "set_octet: %s", v128_hex_string(&c->counter));
   /* fill keystream buffer, if needed */
   if (tail_num) {
     v128_copy(&c->keystream_buffer, &c->counter);
     aes_encrypt(&c->keystream_buffer, &c->expanded_key);
     c->bytes_in_buffer = sizeof(v128_t);
     debug_print(mod_aes_icm, "counter:    %s",
 	      v128_hex_string(&c->counter));
     debug_print(mod_aes_icm, "ciphertext: %s",
 	      v128_hex_string(&c->keystream_buffer));
     /*  indicate number of bytes in keystream_buffer  */
     c->bytes_in_buffer = sizeof(v128_t) - tail_num;
   } else {
     /* indicate that keystream_buffer is empty */
     c->bytes_in_buffer = 0;
   }
   return err_status_ok;
 }
 /*
  * aes_icm_set_iv(c, iv) sets the counter value to the exor of iv with
  * the offset
  */
 err_status_t
 aes_icm_set_iv(aes_icm_ctx_t *c, void *iv) {
   v128_t *nonce = (v128_t *) iv;
   debug_print(mod_aes_icm,
 	      "setting iv: %s", v128_hex_string(nonce));
   v128_xor(&c->counter, &c->offset, nonce);
   debug_print(mod_aes_icm,
 	      "set_counter: %s", v128_hex_string(&c->counter));
   /* indicate that the keystream_buffer is empty */
   c->bytes_in_buffer = 0;
   return err_status_ok;
 }
 /*
  * aes_icm_advance(...) refills the keystream_buffer and
  * advances the block index of the sicm_context forward by one
  *
  * this is an internal, hopefully inlined function
  */
 static inline void
 aes_icm_advance_ismacryp(aes_icm_ctx_t *c, uint8_t forIsmacryp) {
   /* fill buffer with new keystream */
   v128_copy(&c->keystream_buffer, &c->counter);
   aes_encrypt(&c->keystream_buffer, &c->expanded_key);
   c->bytes_in_buffer = sizeof(v128_t);
   debug_print(mod_aes_icm, "counter:    %s",
 	      v128_hex_string(&c->counter));
   debug_print(mod_aes_icm, "ciphertext: %s",
 	      v128_hex_string(&c->keystream_buffer));
   /* clock counter forward */
   if (forIsmacryp) {
     uint32_t temp;
     //alex's clock counter forward
     temp = ntohl(c->counter.v32[3]);
     c->counter.v32[3] = htonl(++temp);
   } else {
     if (!++(c->counter.v8[15]))
       ++(c->counter.v8[14]);
   }
 }
 static inline void aes_icm_advance(aes_icm_ctx_t *c) {
   aes_icm_advance_ismacryp(c, 0);
 }
 /*e
  * icm_encrypt deals with the following cases:
  *
  * bytes_to_encr < bytes_in_buffer
  *  - add keystream into data
  *
  * bytes_to_encr > bytes_in_buffer
  *  - add keystream into data until keystream_buffer is depleted
  *  - loop over blocks, filling keystream_buffer and then
  *    adding keystream into data
  *  - fill buffer then add in remaining (< 16) bytes of keystream
  */
 err_status_t
 aes_icm_encrypt_ismacryp(aes_icm_ctx_t *c,
               unsigned char *buf, unsigned int *enc_len,
               int forIsmacryp) {
   unsigned int bytes_to_encr = *enc_len;
   unsigned int i;
   uint32_t *b;
   /* check that there's enough segment left but not for ismacryp*/
   if (!forIsmacryp && (bytes_to_encr + htons(c->counter.v16[7])) > 0xffff)
     return err_status_terminus;
  debug_print(mod_aes_icm, "block index: %d",
            htons(c->counter.v16[7]));
   if (bytes_to_encr <= (unsigned int)c->bytes_in_buffer) {
     /* deal with odd case of small bytes_to_encr */
     for (i = (sizeof(v128_t) - c->bytes_in_buffer);
 		 i < (sizeof(v128_t) - c->bytes_in_buffer + bytes_to_encr); i++)
 	{
       *buf++ ^= c->keystream_buffer.v8[i];
 	}
     c->bytes_in_buffer -= bytes_to_encr;
     /* return now to avoid the main loop */
     return err_status_ok;
   } else {
     /* encrypt bytes until the remaining data is 16-byte aligned */
     for (i=(sizeof(v128_t) - c->bytes_in_buffer); i < sizeof(v128_t); i++)
       *buf++ ^= c->keystream_buffer.v8[i];
     bytes_to_encr -= c->bytes_in_buffer;
     c->bytes_in_buffer = 0;
   }
   /* now loop over entire 16-byte blocks of keystream */
   for (i=0; i < (bytes_to_encr/sizeof(v128_t)); i++) {
     /* fill buffer with new keystream */
     aes_icm_advance_ismacryp(c, forIsmacryp);
     /*
      * add keystream into the data buffer (this would be a lot faster
      * if we could assume 32-bit alignment!)
      */
 #if ALIGN_32
     b = (uint32_t *)buf;
     *b++ ^= c->keystream_buffer.v32[0];
     *b++ ^= c->keystream_buffer.v32[1];
     *b++ ^= c->keystream_buffer.v32[2];
     *b++ ^= c->keystream_buffer.v32[3];
     buf = (uint8_t *)b;
 #else
     if ((((unsigned long) buf) & 0x03) != 0) {
       *buf++ ^= c->keystream_buffer.v8[0];
       *buf++ ^= c->keystream_buffer.v8[1];
       *buf++ ^= c->keystream_buffer.v8[2];
       *buf++ ^= c->keystream_buffer.v8[3];
       *buf++ ^= c->keystream_buffer.v8[4];
       *buf++ ^= c->keystream_buffer.v8[5];
       *buf++ ^= c->keystream_buffer.v8[6];
       *buf++ ^= c->keystream_buffer.v8[7];
       *buf++ ^= c->keystream_buffer.v8[8];
       *buf++ ^= c->keystream_buffer.v8[9];
       *buf++ ^= c->keystream_buffer.v8[10];
       *buf++ ^= c->keystream_buffer.v8[11];
       *buf++ ^= c->keystream_buffer.v8[12];
       *buf++ ^= c->keystream_buffer.v8[13];
       *buf++ ^= c->keystream_buffer.v8[14];
       *buf++ ^= c->keystream_buffer.v8[15];
     } else {
       b = (uint32_t *)buf;
       *b++ ^= c->keystream_buffer.v32[0];
       *b++ ^= c->keystream_buffer.v32[1];
       *b++ ^= c->keystream_buffer.v32[2];
       *b++ ^= c->keystream_buffer.v32[3];
       buf = (uint8_t *)b;
     }
 #endif /* #if ALIGN_32 */
   }
   /* if there is a tail end of the data, process it */
   if ((bytes_to_encr & 0xf) != 0) {
     /* fill buffer with new keystream */
     aes_icm_advance_ismacryp(c, forIsmacryp);
     for (i=0; i < (bytes_to_encr & 0xf); i++)
       *buf++ ^= c->keystream_buffer.v8[i];
     /* reset the keystream buffer size to right value */
     c->bytes_in_buffer = sizeof(v128_t) - i;
   } else {
     /* no tail, so just reset the keystream buffer size to zero */
     c->bytes_in_buffer = 0;
   }
   return err_status_ok;
 }
 err_status_t
 aes_icm_encrypt(aes_icm_ctx_t *c, unsigned char *buf, unsigned int *enc_len) {
   return aes_icm_encrypt_ismacryp(c, buf, enc_len, 0);
 }
 err_status_t
 aes_icm_output(aes_icm_ctx_t *c, uint8_t *buffer, int num_octets_to_output) {
   unsigned int len = num_octets_to_output;
   /* zeroize the buffer */
   octet_string_set_to_zero(buffer, num_octets_to_output);
   /* exor keystream into buffer */
   return aes_icm_encrypt(c, buffer, &len);
 }
 char
 aes_icm_description[] = "aes integer counter mode";
 uint8_t aes_icm_test_case_0_key[30] = {
 x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,
 xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c,
 xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
 xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd
 };
 uint8_t aes_icm_test_case_0_nonce[16] = {
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 };
 uint8_t aes_icm_test_case_0_plaintext[32] =  {
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 };
 uint8_t aes_icm_test_case_0_ciphertext[32] = {
 xe0, 0x3e, 0xad, 0x09, 0x35, 0xc9, 0x5e, 0x80,
 xe1, 0x66, 0xb1, 0x6d, 0xd9, 0x2b, 0x4e, 0xb4,
 xd2, 0x35, 0x13, 0x16, 0x2b, 0x02, 0xd0, 0xf7,
 x2a, 0x43, 0xa2, 0xfe, 0x4a, 0x5f, 0x97, 0xab
 };
 cipher_test_case_t aes_icm_test_case_0 = {
 ,                                    /* octets in key            */
   aes_icm_test_case_0_key,               /* key                      */
   aes_icm_test_case_0_nonce,             /* packet index             */
 ,                                    /* octets in plaintext      */
   aes_icm_test_case_0_plaintext,         /* plaintext                */
 ,                                    /* octets in ciphertext     */
   aes_icm_test_case_0_ciphertext,        /* ciphertext               */
   NULL                                   /* pointer to next testcase */
 };
 uint8_t aes_icm_test_case_1_key[46] = {
 x57, 0xf8, 0x2f, 0xe3, 0x61, 0x3f, 0xd1, 0x70,
 xa8, 0x5e, 0xc9, 0x3c, 0x40, 0xb1, 0xf0, 0x92,
 x2e, 0xc4, 0xcb, 0x0d, 0xc0, 0x25, 0xb5, 0x82,
 x72, 0x14, 0x7c, 0xc4, 0x38, 0x94, 0x4a, 0x98,
 xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
 xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd
 };
 uint8_t aes_icm_test_case_1_nonce[16] = {
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 };
 uint8_t aes_icm_test_case_1_plaintext[32] =  {
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 };
 uint8_t aes_icm_test_case_1_ciphertext[32] = {
 x92, 0xbd, 0xd2, 0x8a, 0x93, 0xc3, 0xf5, 0x25,
 x11, 0xc6, 0x77, 0xd0, 0x8b, 0x55, 0x15, 0xa4,
 x9d, 0xa7, 0x1b, 0x23, 0x78, 0xa8, 0x54, 0xf6,
 x70, 0x50, 0x75, 0x6d, 0xed, 0x16, 0x5b, 0xac
 };
 cipher_test_case_t aes_icm_test_case_1 = {
 ,                                    /* octets in key            */
   aes_icm_test_case_1_key,               /* key                      */
   aes_icm_test_case_1_nonce,             /* packet index             */
 ,                                    /* octets in plaintext      */
   aes_icm_test_case_1_plaintext,         /* plaintext                */
 ,                                    /* octets in ciphertext     */
   aes_icm_test_case_1_ciphertext,        /* ciphertext               */
   &aes_icm_test_case_0                   /* pointer to next testcase */
 };
 /*
  * note: the encrypt function is identical to the decrypt function
  */
 cipher_type_t aes_icm = {
   (cipher_alloc_func_t)          aes_icm_alloc,
   (cipher_dealloc_func_t)        aes_icm_dealloc,
   (cipher_init_func_t)           aes_icm_context_init,
   (cipher_encrypt_func_t)        aes_icm_encrypt,
   (cipher_decrypt_func_t)        aes_icm_encrypt,
   (cipher_set_iv_func_t)         aes_icm_set_iv,
   (char *)                       aes_icm_description,
   (int)                          0,   /* instance count */
   (cipher_test_case_t *)        &aes_icm_test_case_1,
   (debug_module_t *)            &mod_aes_icm,
   (cipher_type_id_t)             AES_ICM
 };

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netwerk/srtp/src/crypto/cipher/aes_icm.c@6474c204b198 (annotated)

netwerk/srtp/src/crypto/cipher/aes_icm.c