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-rw-r--r--srtp/ekt.c275
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diff --git a/srtp/ekt.c b/srtp/ekt.c
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--- a/srtp/ekt.c
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-/*
- * ekt.c
- *
- * Encrypted Key Transport for SRTP
- *
- * David 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 "err.h"
-#include "srtp_priv.h"
-#include "ekt.h"
-
-extern 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 24
-#define EKT_OCTETS_AFTER_EMK 8
-#define EKT_OCTETS_AFTER_ROC 4
-#define EKT_SPI_LEN 2
-
-unsigned
-ekt_octets_after_base_tag(ekt_stream_t ekt) {
- /*
- * if the pointer ekt is NULL, then EKT is not in effect, so we
- * indicate this by returning zero
- */
- if (!ekt)
- return 0;
-
- switch(ekt->data->ekt_cipher_type) {
- case EKT_CIPHER_AES_128_ECB:
- return 16 + EKT_OCTETS_AFTER_EMK;
- break;
- default:
- break;
- }
- return 0;
-}
-
-static inline ekt_spi_t
-srtcp_packet_get_ekt_spi(const uint8_t *packet_start, unsigned pkt_octet_len) {
- const uint8_t *spi_location;
-
- spi_location = packet_start + (pkt_octet_len - EKT_SPI_LEN);
-
- return *((const ekt_spi_t *)spi_location);
-}
-
-static inline uint32_t
-srtcp_packet_get_ekt_roc(const uint8_t *packet_start, unsigned pkt_octet_len) {
- const uint8_t *roc_location;
-
- roc_location = packet_start + (pkt_octet_len - EKT_OCTETS_AFTER_ROC);
-
- return *((const uint32_t *)roc_location);
-}
-
-static inline const uint8_t *
-srtcp_packet_get_emk_location(const uint8_t *packet_start,
- unsigned pkt_octet_len) {
- const uint8_t *location;
-
- location = packet_start + (pkt_octet_len - EKT_OCTETS_AFTER_BASE_TAG);
-
- return location;
-}
-
-
-err_status_t
-ekt_alloc(ekt_stream_t *stream_data, ekt_policy_t policy) {
-
- /*
- * if the policy pointer is NULL, then EKT is not in use
- * so we just set the EKT stream data pointer to NULL
- */
- if (!policy) {
- *stream_data = NULL;
- return err_status_ok;
- }
-
- /* TODO */
- *stream_data = NULL;
-
- return err_status_ok;
-}
-
-err_status_t
-ekt_stream_init_from_policy(ekt_stream_t stream_data, ekt_policy_t policy) {
- if (!stream_data)
- return err_status_ok;
-
- return err_status_ok;
-}
-
-
-void
-aes_decrypt_with_raw_key(void *ciphertext, const void *key) {
- aes_expanded_key_t expanded_key;
-
- aes_expand_decryption_key(key, expanded_key);
- aes_decrypt(ciphertext, expanded_key);
-}
-
-/*
- * The function srtp_stream_init_from_ekt() initializes a stream using
- * the EKT data from an SRTCP trailer.
- */
-
-err_status_t
-srtp_stream_init_from_ekt(srtp_stream_t stream,
- const void *srtcp_hdr,
- unsigned pkt_octet_len) {
- err_status_t err;
- const uint8_t *master_key;
- srtp_policy_t srtp_policy;
- unsigned master_key_len;
- uint32_t roc;
-
- /*
- * NOTE: at present, we only support a single ekt_policy at a time.
- */
- if (stream->ekt->data->spi !=
- srtcp_packet_get_ekt_spi(srtcp_hdr, pkt_octet_len))
- return err_status_no_ctx;
-
- if (stream->ekt->data->ekt_cipher_type != EKT_CIPHER_AES_128_ECB)
- return err_status_bad_param;
- master_key_len = 16;
-
- /* decrypt the Encrypted Master Key field */
- master_key = srtcp_packet_get_emk_location(srtcp_hdr, pkt_octet_len);
- aes_decrypt_with_raw_key((void*)master_key, stream->ekt->data->ekt_dec_key);
-
- /* set the SRTP ROC */
- roc = srtcp_packet_get_ekt_roc(srtcp_hdr, pkt_octet_len);
- err = rdbx_set_roc(&stream->rtp_rdbx, roc);
- if (err) return err;
-
- err = srtp_stream_init(stream, &srtp_policy);
- if (err) return err;
-
- return err_status_ok;
-}
-
-void
-ekt_write_data(ekt_stream_t ekt,
- void *base_tag,
- unsigned base_tag_len,
- int *packet_len,
- xtd_seq_num_t pkt_index) {
- uint32_t roc;
- uint16_t isn;
- unsigned emk_len;
- uint8_t *packet;
-
- /* if the pointer ekt is NULL, then EKT is not in effect */
- if (!ekt) {
- debug_print(mod_srtp, "EKT not in use", NULL);
- return;
- }
-
- /* write zeros into the location of the base tag */
- octet_string_set_to_zero(base_tag, base_tag_len);
- packet = (uint8_t*)base_tag + base_tag_len;
-
- /* copy encrypted master key into packet */
- emk_len = ekt_octets_after_base_tag(ekt);
- memcpy(packet, ekt->encrypted_master_key, emk_len);
- debug_print(mod_srtp, "writing EKT EMK: %s,",
- octet_string_hex_string(packet, emk_len));
- packet += emk_len;
-
- /* copy ROC into packet */
- roc = (uint32_t)(pkt_index >> 16);
- *((uint32_t *)packet) = be32_to_cpu(roc);
- debug_print(mod_srtp, "writing EKT ROC: %s,",
- octet_string_hex_string(packet, sizeof(roc)));
- packet += sizeof(roc);
-
- /* copy ISN into packet */
- isn = (uint16_t)pkt_index;
- *((uint16_t *)packet) = htons(isn);
- debug_print(mod_srtp, "writing EKT ISN: %s,",
- octet_string_hex_string(packet, sizeof(isn)));
- packet += sizeof(isn);
-
- /* copy SPI into packet */
- *((uint16_t *)packet) = htons(ekt->data->spi);
- debug_print(mod_srtp, "writing EKT SPI: %s,",
- octet_string_hex_string(packet, sizeof(ekt->data->spi)));
-
- /* increase packet length appropriately */
- *packet_len += EKT_OCTETS_AFTER_EMK + emk_len;
-}
-
-
-/*
- * 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(ekt_stream_t ekt,
- unsigned *auth_len,
- void **auth_tag,
- void *tag_copy) {
-
- /*
- * if there is no EKT policy, then the other inputs are unaffected
- */
- if (!ekt)
- return;
-
- /* copy auth_tag into temporary location */
-
-}
-
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-28 20:46:26 +0000