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Diffstat (limited to 'netwerk/srtp/src/include/ekt.h')
| -rw-r--r-- | netwerk/srtp/src/include/ekt.h | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/netwerk/srtp/src/include/ekt.h b/netwerk/srtp/src/include/ekt.h new file mode 100644 index 000000000..b0d888bac --- /dev/null +++ b/netwerk/srtp/src/include/ekt.h @@ -0,0 +1,201 @@ +/* + * ekt.h + * + * interface to Encrypted Key Transport for SRTP + * + * David McGrew + * Cisco Systems, Inc. + */ +/* + * + * Copyright (c) 2001-2005 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. + * + */ + + + +/* + * EKT implementation strategy + * + * use stream_template approach + * + * in srtp_unprotect, when a new stream appears, check if template has + * EKT defined, and if it does, then apply EKT processing + * + * question: will we want to allow key-sharing templates in addition + * to EKT templates? could define a new ssrc_type_t that's associated + * with an EKT, e.g. ssrc_any_ekt. + * + * + */ + +#ifndef EKT_H +#define EKT_H + +#ifdef __cplusplus +extern "C" { +#endif + +#include "srtp_priv.h" + +#define EKT_CIPHER_DEFAULT 1 +#define EKT_CIPHER_AES_128_ECB 1 +#define EKT_CIPHER_AES_192_KEY_WRAP 2 +#define EKT_CIPHER_AES_256_KEY_WRAP 3 + +typedef uint16_t ekt_spi_t; + + +unsigned +ekt_octets_after_base_tag(ekt_stream_t ekt); + +/* + * an srtp_policy_t structure can contain a pointer to an + * ekt_policy_t structure + * + * this structure holds all of the high level EKT information, and it + * is passed into libsrtp to indicate what policy should be in effect + */ + +typedef struct ekt_policy_ctx_t { + ekt_spi_t spi; /* security parameter index */ + uint8_t ekt_cipher_type; + uint8_t *ekt_key; + struct ekt_policy_ctx_t *next_ekt_policy; +} ekt_policy_ctx_t; + + +/* + * an ekt_data_t structure holds the data corresponding to an ekt key, + * spi, and so on + */ + +typedef struct ekt_data_t { + ekt_spi_t spi; + uint8_t ekt_cipher_type; + aes_expanded_key_t ekt_enc_key; + aes_expanded_key_t ekt_dec_key; + struct ekt_data_t *next_ekt_data; +} ekt_data_t; + +/* + * an srtp_stream_ctx_t can contain an ekt_stream_ctx_t + * + * an ekt_stream_ctx_t structure holds all of the EKT information for + * a specific SRTP stream + */ + +typedef struct ekt_stream_ctx_t { + ekt_data_t *data; + uint16_t isn; /* initial sequence number */ + uint8_t encrypted_master_key[SRTP_MAX_KEY_LEN]; +} ekt_stream_ctx_t; + + + +err_status_t +ekt_alloc(ekt_stream_t *stream_data, ekt_policy_t policy); + +err_status_t +ekt_stream_init(ekt_stream_t e, + ekt_spi_t spi, + void *ekt_key, + unsigned ekt_cipher_type); + +err_status_t +ekt_stream_init_from_policy(ekt_stream_t e, ekt_policy_t p); + + + +err_status_t +srtp_stream_init_from_ekt(srtp_stream_t stream, + const void *srtcp_hdr, + unsigned pkt_octet_len); + + +void +ekt_write_data(ekt_stream_t ekt, + uint8_t *base_tag, + unsigned base_tag_len, + int *packet_len, + xtd_seq_num_t pkt_index); + +/* + * We handle EKT by performing some additional steps before + * authentication (copying the auth tag into a temporary location, + * zeroizing the "base tag" field in the packet) + * + * With EKT, the tag_len parameter is actually the base tag + * length + */ + +err_status_t +ekt_tag_verification_preproces(uint8_t *pkt_tag, + uint8_t *pkt_tag_copy, + unsigned tag_len); + +err_status_t +ekt_tag_verification_postproces(uint8_t *pkt_tag, + uint8_t *pkt_tag_copy, + unsigned tag_len); + + +/* + * @brief EKT pre-processing for srtcp tag generation + * + * This function does the pre-processing of the SRTCP authentication + * tag format. When EKT is used, it consists of writing the Encrypted + * Master Key, the SRTP ROC, the Initial Sequence Number, and SPI + * fields. The Base Authentication Tag field is set to the all-zero + * value + * + * When EKT is not used, this function is a no-op. + * + */ + +err_status_t +srtp_stream_srtcp_auth_tag_generation_preprocess(const srtp_stream_t *s, + uint8_t *pkt_tag, + unsigned pkt_octet_len); + +/* it's not clear that a tag_generation_postprocess function is needed */ + +err_status_t +srtcp_auth_tag_generation_postprocess(void); + + +#ifdef __cplusplus +} +#endif + +#endif /* EKT_H */ |