Add current version of libSRTP from CVS.

libsrtp/include/ekt.h

+/*
+ * 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 */