chromium/third_party/libsrtp/srtp/ekt.c

/*
 * ekt.c
 *
 * Encrypted Key Transport for SRTP
 *
 * David McGrew
 * Cisco Systems, Inc.
 */
/*
 *
 * Copyright (c) 2001-2017 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 "srtp_priv.h"
#include "err.h"
#include "ekt.h"

extern srtp_debug_module_t mod_srtp;

/*
 *  The EKT Authentication Tag format.
 *
 *    0                   1                   2                   3
 *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   :                   Base Authentication Tag                     :
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   :                     Encrypted Master Key                      :
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                       Rollover Counter                        |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |    Initial Sequence Number    |   Security Parameter Index    |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 */

#define EKT_OCTETS_AFTER_BASE_TAG …
#define EKT_OCTETS_AFTER_EMK …
#define EKT_OCTETS_AFTER_ROC …
#define EKT_SPI_LEN …

unsigned srtp_ekt_octets_after_base_tag(srtp_ekt_stream_t ekt)
{ … }

static inline srtp_ekt_spi_t srtcp_packet_get_ekt_spi(
    const uint8_t *packet_start,
    unsigned pkt_octet_len)
{ … }

static inline uint32_t srtcp_packet_get_ekt_roc(const uint8_t *packet_start,
                                                unsigned pkt_octet_len)
{ … }

static inline const uint8_t *srtcp_packet_get_emk_location(
    const uint8_t *packet_start,
    unsigned pkt_octet_len)
{ … }

srtp_err_status_t srtp_ekt_alloc(srtp_ekt_stream_t *stream_data,
                                 srtp_ekt_policy_t policy)
{ … }

srtp_err_status_t srtp_ekt_stream_init_from_policy(
    srtp_ekt_stream_t stream_data,
    srtp_ekt_policy_t policy)
{ … }

void aes_decrypt_with_raw_key(void *ciphertext, const void *key, int key_len)
{ … }

/*
 * The function srtp_stream_init_from_ekt() initializes a stream using
 * the EKT data from an SRTCP trailer.
 */

srtp_err_status_t srtp_stream_init_from_ekt(srtp_stream_t stream,
                                            const void *srtcp_hdr,
                                            unsigned pkt_octet_len)
{ … }

void srtp_ekt_write_data(srtp_ekt_stream_t ekt,
                         uint8_t *base_tag,
                         unsigned base_tag_len,
                         int *packet_len,
                         srtp_xtd_seq_num_t pkt_index)
{ … }

/*
 * The function call srtcp_ekt_trailer(ekt, auth_len, auth_tag   )
 *
 * If the pointer ekt is NULL, then the other inputs are unaffected.
 *
 * auth_tag is a pointer to the pointer to the location of the
 * authentication tag in the packet.  If EKT is in effect, then the
 * auth_tag pointer is set to the location
 */

void srtcp_ekt_trailer(srtp_ekt_stream_t ekt,
                       unsigned *auth_len,
                       void **auth_tag,
                       void *tag_copy)
{ … }