~ubuntu-branches/ubuntu/vivid/sflphone/vivid

/*

 * 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 = {

  0,                 /* 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 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 != 30)

    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) {

  v128_t tmp_key;

  /* set counter and initial values to 'offset' value */

  /* FIX!!! this assumes the salt is at key + 16, and thus that the */

  /* FIX!!! cipher key length is 16!  Also note this copies past the

            end of the 'key' array by 2 bytes! */

  v128_copy_octet_string(&c->counter, key + 16);

  v128_copy_octet_string(&c->offset, key + 16);

  /* force last two octets of the offset to zero (for srtp compatibility) */

  c->offset.v8[14] = c->offset.v8[15] = 0;

  c->counter.v8[14] = c->counter.v8[15] = 0;

  /* set tmp_key (for alignment) */

  v128_copy_octet_string(&tmp_key, key);

  debug_print(mod_aes_icm,

	      "key:  %s", v128_hex_string(&tmp_key));

  debug_print(mod_aes_icm,

	      "offset: %s", v128_hex_string(&c->offset));

  /* expand key */

  aes_expand_encryption_key(&tmp_key, c->expanded_key);

  /* 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       = 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

 */

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]);

  }

}

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] = {

  0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,

  0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c,

  0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,

  0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd

};

uint8_t aes_icm_test_case_0_nonce[16] = {

  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00

};

uint8_t aes_icm_test_case_0_plaintext[32] =  {

  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

};

uint8_t aes_icm_test_case_0_ciphertext[32] = {

  0xe0, 0x3e, 0xad, 0x09, 0x35, 0xc9, 0x5e, 0x80,

  0xe1, 0x66, 0xb1, 0x6d, 0xd9, 0x2b, 0x4e, 0xb4,

  0xd2, 0x35, 0x13, 0x16, 0x2b, 0x02, 0xd0, 0xf7,

  0x2a, 0x43, 0xa2, 0xfe, 0x4a, 0x5f, 0x97, 0xab

};

cipher_test_case_t aes_icm_test_case_0 = {

  30,                                    /* octets in key            */

  aes_icm_test_case_0_key,               /* key                      */

  aes_icm_test_case_0_nonce,             /* packet index             */

  32,                                    /* octets in plaintext      */

  aes_icm_test_case_0_plaintext,         /* plaintext                */

  32,                                    /* octets in ciphertext     */

  aes_icm_test_case_0_ciphertext,        /* ciphertext               */

  NULL                                   /* 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_0,

  (debug_module_t *)            &mod_aes_icm

};