Update libsrtp to version 2.0

srtp/include/srtp.h

Index: srtp/include/srtp.h
diff --git a/srtp/include/srtp.h b/srtp/include/srtp.h
deleted file mode 100644
index 89834b12011ab9f2a426a73ccff4bbc95068a95b..0000000000000000000000000000000000000000
--- a/srtp/include/srtp.h
+++ /dev/null
@@ -1,1283 +0,0 @@
-/*
- * srtp.h
- *
- * interface to libsrtp
- *
- * 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.
- *
- */
-
-
-#ifndef SRTP_H
-#define SRTP_H
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#include <stdint.h>
-#include "crypto.h" 
-#include "crypto_types.h"
-#include "err.h"
-
-/*
- * Compatibility shim for v1->v2 transition.
- */
-
-#define srtp_crypto_policy_set_aes_cm_128_hmac_sha1_32 \
-    crypto_policy_set_aes_cm_128_hmac_sha1_32
-#define srtp_crypto_policy_set_aes_cm_128_hmac_sha1_80 \
-    crypto_policy_set_aes_cm_128_hmac_sha1_80
-#define srtp_crypto_policy_set_aes_gcm_128_16_auth \
-    crypto_policy_set_aes_gcm_128_16_auth
-#define srtp_crypto_policy_set_aes_gcm_256_16_auth \
-    crypto_policy_set_aes_gcm_256_16_auth
-
-#define srtp_ssrc_type_t ssrc_type_t
-
-/**
- * @defgroup SRTP Secure RTP
- *
- * @brief libSRTP provides functions for protecting RTP and RTCP.  See
- * Section @ref Overview for an introduction to the use of the library.
- *
- * @{
- */
-
-/*
- * SRTP_MASTER_KEY_LEN is the nominal master key length supported by libSRTP
- */
-
-#define SRTP_MASTER_KEY_LEN 30
-
-/*
- * SRTP_MAX_KEY_LEN is the maximum key length supported by libSRTP
- */
-#define SRTP_MAX_KEY_LEN      64
-
-/*
- * SRTP_MAX_TAG_LEN is the maximum tag length supported by libSRTP
- */
-
-#define SRTP_MAX_TAG_LEN 16 
-
-/**
- * SRTP_MAX_TRAILER_LEN is the maximum length of the SRTP trailer
- * (authentication tag and MKI) supported by libSRTP.  This value is
- * the maximum number of octets that will be added to an RTP packet by
- * srtp_protect().
- *
- * @brief the maximum number of octets added by srtp_protect().
- */
-#define SRTP_MAX_TRAILER_LEN SRTP_MAX_TAG_LEN 
-
-/*
- * SRTP_AEAD_SALT_LEN is the length of the SALT values used with 
- * GCM mode.  GCM mode requires an IV.  The SALT value is used
- * as part of the IV formation logic applied to each RTP packet.
- */
-#define SRTP_AEAD_SALT_LEN	12
-#define AES_128_GCM_KEYSIZE_WSALT   SRTP_AEAD_SALT_LEN + 16
-#define AES_192_GCM_KEYSIZE_WSALT   SRTP_AEAD_SALT_LEN + 24
-#define AES_256_GCM_KEYSIZE_WSALT   SRTP_AEAD_SALT_LEN + 32
-
-
-
-/* 
- * nota bene: since libSRTP doesn't support the use of the MKI, the
- * SRTP_MAX_TRAILER_LEN value is just the maximum tag length
- */
-
-/**
- * @brief sec_serv_t describes a set of security services. 
- *
- * A sec_serv_t enumeration is used to describe the particular
- * security services that will be applied by a particular crypto
- * policy (or other mechanism).  
- */
-
-typedef enum {
-  sec_serv_none          = 0, /**< no services                        */
-  sec_serv_conf          = 1, /**< confidentiality                    */
-  sec_serv_auth          = 2, /**< authentication                     */
-  sec_serv_conf_and_auth = 3  /**< confidentiality and authentication */
-} sec_serv_t;
-
-/** 
- * @brief crypto_policy_t describes a particular crypto policy that
- * can be applied to an SRTP stream.
- *
- * A crypto_policy_t describes a particular cryptographic policy that
- * can be applied to an SRTP or SRTCP stream.  An SRTP session policy
- * consists of a list of these policies, one for each SRTP stream 
- * in the session.
- */
-
-typedef struct crypto_policy_t {
-  cipher_type_id_t cipher_type;    /**< An integer representing
-				    *   the type of cipher.  */
-  int              cipher_key_len; /**< The length of the cipher key
-				    *   in octets.                       */
-  auth_type_id_t   auth_type;      /**< An integer representing the
-				    *   authentication function.         */
-  int              auth_key_len;   /**< The length of the authentication 
-				    *   function key in octets.          */
-  int              auth_tag_len;   /**< The length of the authentication 
-				    *   tag in octets.                   */
-  sec_serv_t       sec_serv;       /**< The flag indicating the security
-				    *   services to be applied.          */
-} crypto_policy_t;
-
-
-/** 
- * @brief ssrc_type_t describes the type of an SSRC.
- * 
- * An ssrc_type_t enumeration is used to indicate a type of SSRC.  See
- * @ref srtp_policy_t for more informataion.
- */
-
-typedef enum { 
-  ssrc_undefined    = 0,  /**< Indicates an undefined SSRC type. */
-  ssrc_specific     = 1,  /**< Indicates a specific SSRC value   */
-  ssrc_any_inbound  = 2, /**< Indicates any inbound SSRC value 
-			    (i.e. a value that is used in the
-			    function srtp_unprotect())              */
-  ssrc_any_outbound = 3  /**< Indicates any outbound SSRC value 
-			    (i.e. a value that is used in the 
-			    function srtp_protect())		  */
-} ssrc_type_t;
-
-/**
- * @brief An ssrc_t represents a particular SSRC value, or a `wildcard' SSRC.
- * 
- * An ssrc_t represents a particular SSRC value (if its type is
- * ssrc_specific), or a wildcard SSRC value that will match all
- * outbound SSRCs (if its type is ssrc_any_outbound) or all inbound
- * SSRCs (if its type is ssrc_any_inbound).  
- *
- */
-
-typedef struct { 
-  ssrc_type_t type;   /**< The type of this particular SSRC */
-  unsigned int value; /**< The value of this SSRC, if it is not a wildcard */
-} ssrc_t;
-
-
-/**
- * @brief points to an EKT policy
- */
-typedef struct ekt_policy_ctx_t *ekt_policy_t;
-
-
-/**
- * @brief points to EKT stream data
- */
-typedef struct ekt_stream_ctx_t *ekt_stream_t;
-
-
-/** 
- * @brief represents the policy for an SRTP session.  
- *
- * A single srtp_policy_t struct represents the policy for a single
- * SRTP stream, and a linked list of these elements represents the
- * policy for an entire SRTP session.  Each element contains the SRTP
- * and SRTCP crypto policies for that stream, a pointer to the SRTP
- * master key for that stream, the SSRC describing that stream, or a
- * flag indicating a `wildcard' SSRC value, and a `next' field that
- * holds a pointer to the next element in the list of policy elements,
- * or NULL if it is the last element. 
- *
- * The wildcard value SSRC_ANY_INBOUND matches any SSRC from an
- * inbound stream that for which there is no explicit SSRC entry in
- * another policy element.  Similarly, the value SSRC_ANY_OUTBOUND
- * will matches any SSRC from an outbound stream that does not appear
- * in another policy element.  Note that wildcard SSRCs &b cannot be
- * used to match both inbound and outbound traffic.  This restriction
- * is intentional, and it allows libSRTP to ensure that no security
- * lapses result from accidental re-use of SSRC values during key
- * sharing.
- * 
- * 
- * @warning The final element of the list @b must have its `next' pointer
- *          set to NULL.
- */
-
-typedef struct srtp_policy_t {
-  ssrc_t        ssrc;        /**< The SSRC value of stream, or the 
-			      *   flags SSRC_ANY_INBOUND or 
-			      *   SSRC_ANY_OUTBOUND if key sharing
-			      *   is used for this policy element.
-			      */
-  crypto_policy_t rtp;         /**< SRTP crypto policy.                  */
-  crypto_policy_t rtcp;        /**< SRTCP crypto policy.                 */
-  unsigned char *key;          /**< Pointer to the SRTP master key for
-				*    this stream.                        */
-  ekt_policy_t ekt;            /**< Pointer to the EKT policy structure
-                                *   for this stream (if any)             */ 
-  unsigned long window_size;   /**< The window size to use for replay
-				*   protection. */
-  int        allow_repeat_tx;  /**< Whether retransmissions of
-				*   packets with the same sequence number
-				*   are allowed.  (Note that such repeated
-				*   transmissions must have the same RTP
-				*   payload, or a severe security weakness
-				*   is introduced!)                      */
-  int *enc_xtn_hdr;            /**< List of header ids to encrypt.       */
-  int enc_xtn_hdr_count;       /**< Number of entries in list of header ids. */
-  struct srtp_policy_t *next;  /**< Pointer to next stream policy.       */
-} srtp_policy_t;
-
-
-
-
-/**
- * @brief An srtp_t points to an SRTP session structure.
- *
- * The typedef srtp_t is a pointer to a structure that represents
- * an SRTP session.  This datatype is intentially opaque in 
- * order to separate the interface from the implementation.
- *
- * An SRTP session consists of all of the traffic sent to the RTP and
- * RTCP destination transport addresses, using the RTP/SAVP (Secure
- * Audio/Video Profile).  A session can be viewed as a set of SRTP
- * streams, each of which originates with a different participant.
- */
-
-typedef struct srtp_ctx_t *srtp_t;
-
-
-/**
- * @brief An srtp_stream_t points to an SRTP stream structure.
- *
- * The typedef srtp_stream_t is a pointer to a structure that
- * represents an SRTP stream.  This datatype is intentionally
- * opaque in order to separate the interface from the implementation. 
- * 
- * An SRTP stream consists of all of the traffic sent to an SRTP
- * session by a single participant.  A session can be viewed as
- * a set of streams.  
- *
- */
-typedef struct srtp_stream_ctx_t *srtp_stream_t;
-
-
-
-/**
- * @brief srtp_init() initializes the srtp library.  
- *
- * @warning This function @b must be called before any other srtp
- * functions.
- */
-
-err_status_t
-srtp_init(void);
-
-/**
- * @brief srtp_shutdown() de-initializes the srtp library.
- *
- * @warning No srtp functions may be called after calling this function.
- */
-
-err_status_t
-srtp_shutdown(void);
-
-/**
- * @brief srtp_protect() is the Secure RTP sender-side packet processing
- * function.
- * 
- * The function call srtp_protect(ctx, rtp_hdr, len_ptr) applies SRTP
- * protection to the RTP packet rtp_hdr (which has length *len_ptr) using
- * the SRTP context ctx.  If err_status_ok is returned, then rtp_hdr
- * points to the resulting SRTP packet and *len_ptr is the number of
- * octets in that packet; otherwise, no assumptions should be made
- * about the value of either data elements.
- * 
- * The sequence numbers of the RTP packets presented to this function
- * need not be consecutive, but they @b must be out of order by less
- * than 2^15 = 32,768 packets.
- *
- * @warning This function assumes that it can write the authentication
- * tag into the location in memory immediately following the RTP
- * packet, and assumes that the RTP packet is aligned on a 32-bit
- * boundary.
- *
- * @warning This function assumes that it can write SRTP_MAX_TRAILER_LEN 
- * into the location in memory immediately following the RTP packet.   
- * Callers MUST ensure that this much writable memory is available in 
- * the buffer that holds the RTP packet.
- * 
- * @param ctx is the SRTP context to use in processing the packet.
- *
- * @param rtp_hdr is a pointer to the RTP packet (before the call); after
- * the function returns, it points to the srtp packet.
- *
- * @param len_ptr is a pointer to the length in octets of the complete
- * RTP packet (header and body) before the function call, and of the
- * complete SRTP packet after the call, if err_status_ok was returned.
- * Otherwise, the value of the data to which it points is undefined.
- *
- * @return 
- *    - err_status_ok            no problems
- *    - err_status_replay_fail   rtp sequence number was non-increasing
- *    - @e other                 failure in cryptographic mechanisms
- */
-
-err_status_t
-srtp_protect(srtp_t ctx, void *rtp_hdr, int *len_ptr);
-	     
-/**
- * @brief srtp_unprotect() is the Secure RTP receiver-side packet
- * processing function.
- *
- * The function call srtp_unprotect(ctx, srtp_hdr, len_ptr) verifies
- * the Secure RTP protection of the SRTP packet pointed to by srtp_hdr
- * (which has length *len_ptr), using the SRTP context ctx.  If
- * err_status_ok is returned, then srtp_hdr points to the resulting
- * RTP packet and *len_ptr is the number of octets in that packet;
- * otherwise, no assumptions should be made about the value of either
- * data elements.  
- * 
- * The sequence numbers of the RTP packets presented to this function
- * need not be consecutive, but they @b must be out of order by less
- * than 2^15 = 32,768 packets.
- * 
- * @warning This function assumes that the SRTP packet is aligned on a
- * 32-bit boundary.
- *
- * @param ctx is the SRTP session which applies to the particular packet.
- *
- * @param srtp_hdr is a pointer to the header of the SRTP packet
- * (before the call).  after the function returns, it points to the
- * rtp packet if err_status_ok was returned; otherwise, the value of
- * the data to which it points is undefined.
- *
- * @param len_ptr is a pointer to the length in octets of the complete
- * srtp packet (header and body) before the function call, and of the
- * complete rtp packet after the call, if err_status_ok was returned.
- * Otherwise, the value of the data to which it points is undefined.
- *
- * @return 
- *    - err_status_ok          if the RTP packet is valid.
- *    - err_status_auth_fail   if the SRTP packet failed the message 
- *                             authentication check.
- *    - err_status_replay_fail if the SRTP packet is a replay (e.g. packet has
- *                             already been processed and accepted).
- *    - [other]  if there has been an error in the cryptographic mechanisms.
- *
- */
-
-err_status_t
-srtp_unprotect(srtp_t ctx, void *srtp_hdr, int *len_ptr);
-
-
-/**
- * @brief srtp_create() allocates and initializes an SRTP session.
-
- * The function call srtp_create(session, policy, key) allocates and
- * initializes an SRTP session context, applying the given policy and
- * key.
- *
- * @param session is a pointer to the SRTP session to which the policy is
- * to be added.
- * 
- * @param policy is the srtp_policy_t struct that describes the policy
- * for the session.  The struct may be a single element, or it may be
- * the head of a list, in which case each element of the list is
- * processed.  It may also be NULL, in which case streams should be added
- * later using srtp_add_stream().  The final element of the list @b must
- * have its `next' field set to NULL.
- * 
- * @return
- *    - err_status_ok           if creation succeded.
- *    - err_status_alloc_fail   if allocation failed.
- *    - err_status_init_fail    if initialization failed.
- */
-
-err_status_t
-srtp_create(srtp_t *session, const srtp_policy_t *policy);
-
-
-/**
- * @brief srtp_add_stream() allocates and initializes an SRTP stream
- * within a given SRTP session.
- * 
- * The function call srtp_add_stream(session, policy) allocates and
- * initializes a new SRTP stream within a given, previously created
- * session, applying the policy given as the other argument to that
- * stream.
- *
- * @return values:
- *    - err_status_ok           if stream creation succeded.
- *    - err_status_alloc_fail   if stream allocation failed
- *    - err_status_init_fail    if stream initialization failed.
- */
-
-err_status_t
-srtp_add_stream(srtp_t session, 
-		const srtp_policy_t *policy);
-
-
-/**
- * @brief srtp_remove_stream() deallocates an SRTP stream.
- * 
- * The function call srtp_remove_stream(session, ssrc) removes
- * the SRTP stream with the SSRC value ssrc from the SRTP session
- * context given by the argument session.
- *
- * @param session is the SRTP session from which the stream
- *        will be removed.
- *
- * @param ssrc is the SSRC value of the stream to be removed.
- *
- * @warning Wildcard SSRC values cannot be removed from a
- *          session.
- * 
- * @return
- *    - err_status_ok     if the stream deallocation succeded.
- *    - [other]           otherwise.
- *
- */
-
-err_status_t
-srtp_remove_stream(srtp_t session, unsigned int ssrc);
-
-/**
- * @brief crypto_policy_set_rtp_default() sets a crypto policy
- * structure to the SRTP default policy for RTP protection.
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_rtp_default(&p) sets the
- * crypto_policy_t at location p to the SRTP default policy for RTP
- * protection, as defined in the specification.  This function is a
- * convenience that helps to avoid dealing directly with the policy
- * data structure.  You are encouraged to initialize policy elements
- * with this function call.  Doing so may allow your code to be
- * forward compatible with later versions of libSRTP that include more
- * elements in the crypto_policy_t datatype.
- * 
- * @return void.
- * 
- */
-
-void
-crypto_policy_set_rtp_default(crypto_policy_t *p);
-
-/**
- * @brief crypto_policy_set_rtcp_default() sets a crypto policy
- * structure to the SRTP default policy for RTCP protection.
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_rtcp_default(&p) sets the
- * crypto_policy_t at location p to the SRTP default policy for RTCP
- * protection, as defined in the specification.  This function is a
- * convenience that helps to avoid dealing directly with the policy
- * data structure.  You are encouraged to initialize policy elements
- * with this function call.  Doing so may allow your code to be
- * forward compatible with later versions of libSRTP that include more
- * elements in the crypto_policy_t datatype.
- * 
- * @return void.
- * 
- */
-
-void
-crypto_policy_set_rtcp_default(crypto_policy_t *p);
-
-/**
- * @brief crypto_policy_set_aes_cm_128_hmac_sha1_80() sets a crypto
- * policy structure to the SRTP default policy for RTP protection.
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function crypto_policy_set_aes_cm_128_hmac_sha1_80() is a
- * synonym for crypto_policy_set_rtp_default().  It conforms to the
- * naming convention used in RFC 4568 (SDP Security Descriptions for
- * Media Streams).
- * 
- * @return void.
- * 
- */
-
-#define crypto_policy_set_aes_cm_128_hmac_sha1_80(p) crypto_policy_set_rtp_default(p)
-
-
-/**
- * @brief crypto_policy_set_aes_cm_128_hmac_sha1_32() sets a crypto
- * policy structure to a short-authentication tag policy
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_aes_cm_128_hmac_sha1_32(&p)
- * sets the crypto_policy_t at location p to use policy
- * AES_CM_128_HMAC_SHA1_32 as defined in RFC 4568.
- * This policy uses AES-128
- * Counter Mode encryption and HMAC-SHA1 authentication, with an
- * authentication tag that is only 32 bits long.  This length is
- * considered adequate only for protecting audio and video media that
- * use a stateless playback function.  See Section 7.5 of RFC 3711
- * (http://www.ietf.org/rfc/rfc3711.txt).
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @warning This crypto policy is intended for use in SRTP, but not in
- * SRTCP.  It is recommended that a policy that uses longer
- * authentication tags be used for SRTCP.  See Section 7.5 of RFC 3711
- * (http://www.ietf.org/rfc/rfc3711.txt).
- *
- * @return void.
- * 
- */
-
-void
-crypto_policy_set_aes_cm_128_hmac_sha1_32(crypto_policy_t *p);
-
-
-
-/**
- * @brief crypto_policy_set_aes_cm_128_null_auth() sets a crypto
- * policy structure to an encryption-only policy
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_aes_cm_128_null_auth(&p) sets
- * the crypto_policy_t at location p to use the SRTP default cipher
- * (AES-128 Counter Mode), but to use no authentication method.  This
- * policy is NOT RECOMMENDED unless it is unavoidable; see Section 7.5
- * of RFC 3711 (http://www.ietf.org/rfc/rfc3711.txt).
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @warning This policy is NOT RECOMMENDED for SRTP unless it is
- * unavoidable, and it is NOT RECOMMENDED at all for SRTCP; see
- * Section 7.5 of RFC 3711 (http://www.ietf.org/rfc/rfc3711.txt).
- *
- * @return void.
- * 
- */
-
-void
-crypto_policy_set_aes_cm_128_null_auth(crypto_policy_t *p);
-
-
-/**
- * @brief crypto_policy_set_null_cipher_hmac_sha1_80() sets a crypto
- * policy structure to an authentication-only policy
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_null_cipher_hmac_sha1_80(&p)
- * sets the crypto_policy_t at location p to use HMAC-SHA1 with an 80
- * bit authentication tag to provide message authentication, but to
- * use no encryption.  This policy is NOT RECOMMENDED for SRTP unless
- * there is a requirement to forego encryption.  
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @warning This policy is NOT RECOMMENDED for SRTP unless there is a
- * requirement to forego encryption.  
- *
- * @return void.
- * 
- */
-
-void
-crypto_policy_set_null_cipher_hmac_sha1_80(crypto_policy_t *p);
-
-
-/**
- * @brief crypto_policy_set_aes_cm_256_hmac_sha1_80() sets a crypto
- * policy structure to a encryption and authentication policy using AES-256 
- * for RTP protection.
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_aes_cm_256_hmac_sha1_80(&p)
- * sets the crypto_policy_t at location p to use policy
- * AES_CM_256_HMAC_SHA1_80 as defined in
- * draft-ietf-avt-srtp-big-aes-03.txt.  This policy uses AES-256
- * Counter Mode encryption and HMAC-SHA1 authentication, with an 80 bit
- * authentication tag.
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @return void.
- * 
- */
-
-void crypto_policy_set_aes_cm_256_hmac_sha1_80(crypto_policy_t *p);
-
-
-/**
- * @brief crypto_policy_set_aes_cm_256_hmac_sha1_32() sets a crypto
- * policy structure to a short-authentication tag policy using AES-256
- * encryption.
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_aes_cm_256_hmac_sha1_32(&p)
- * sets the crypto_policy_t at location p to use policy
- * AES_CM_256_HMAC_SHA1_32 as defined in
- * draft-ietf-avt-srtp-big-aes-03.txt.  This policy uses AES-256
- * Counter Mode encryption and HMAC-SHA1 authentication, with an
- * authentication tag that is only 32 bits long.  This length is
- * considered adequate only for protecting audio and video media that
- * use a stateless playback function.  See Section 7.5 of RFC 3711
- * (http://www.ietf.org/rfc/rfc3711.txt).
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @warning This crypto policy is intended for use in SRTP, but not in
- * SRTCP.  It is recommended that a policy that uses longer
- * authentication tags be used for SRTCP.  See Section 7.5 of RFC 3711
- * (http://www.ietf.org/rfc/rfc3711.txt).
- *
- * @return void.
- * 
- */
-
-void
-crypto_policy_set_aes_cm_256_hmac_sha1_32(crypto_policy_t *p);
-
-/**
- * @brief crypto_policy_set_aes_cm_256_null_auth() sets a crypto
- * policy structure to an encryption-only policy
- *
- * @param p is a pointer to the policy structure to be set
- *
- * The function call crypto_policy_set_aes_cm_256_null_auth(&p) sets
- * the crypto_policy_t at location p to use the SRTP default cipher
- * (AES-256 Counter Mode), but to use no authentication method.  This
- * policy is NOT RECOMMENDED unless it is unavoidable; see Section 7.5
- * of RFC 3711 (http://www.ietf.org/rfc/rfc3711.txt).
- *
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @warning This policy is NOT RECOMMENDED for SRTP unless it is
- * unavoidable, and it is NOT RECOMMENDED at all for SRTCP; see
- * Section 7.5 of RFC 3711 (http://www.ietf.org/rfc/rfc3711.txt).
- *
- * @return void.
- *
- */
-void
-crypto_policy_set_aes_cm_256_null_auth(crypto_policy_t *p);
-
-/**
- * @brief crypto_policy_set_aes_gcm_128_8_auth() sets a crypto
- * policy structure to an AEAD encryption policy.
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_aes_gcm_128_8_auth(&p) sets
- * the crypto_policy_t at location p to use the SRTP default cipher
- * (AES-128 Galois Counter Mode) with 8 octet auth tag.  This
- * policy applies confidentiality and authentication to both the
- * RTP and RTCP packets.
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @return void.
- * 
- */
-void
-crypto_policy_set_aes_gcm_128_8_auth(crypto_policy_t *p);
-
-/**
- * @brief crypto_policy_set_aes_gcm_256_8_auth() sets a crypto
- * policy structure to an AEAD encryption policy
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_aes_gcm_256_8_auth(&p) sets
- * the crypto_policy_t at location p to use the SRTP default cipher
- * (AES-256 Galois Counter Mode) with 8 octet auth tag.  This 
- * policy applies confidentiality and authentication to both the
- * RTP and RTCP packets.
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @return void.
- * 
- */
-void
-crypto_policy_set_aes_gcm_256_8_auth(crypto_policy_t *p);
-
-/**
- * @brief crypto_policy_set_aes_gcm_128_8_only_auth() sets a crypto
- * policy structure to an AEAD authentication-only policy
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_aes_gcm_128_8_only_auth(&p) sets
- * the crypto_policy_t at location p to use the SRTP default cipher
- * (AES-128 Galois Counter Mode) with 8 octet auth tag.  This policy 
- * applies confidentiality and authentication to the RTP packets, 
- * but only authentication to the RTCP packets.
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @return void.
- * 
- */
-void
-crypto_policy_set_aes_gcm_128_8_only_auth(crypto_policy_t *p);
-
-/**
- * @brief crypto_policy_set_aes_gcm_256_8_only_auth() sets a crypto
- * policy structure to an AEAD authentication-only policy
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_aes_gcm_256_8_only_auth(&p) sets
- * the crypto_policy_t at location p to use the SRTP default cipher
- * (AES-256 Galois Counter Mode) with 8 octet auth tag.  This policy 
- * applies confidentiality and authentication to the RTP packets, 
- * but only authentication to the RTCP packets.
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @return void.
- * 
- */
-void
-crypto_policy_set_aes_gcm_256_8_only_auth(crypto_policy_t *p);
-
-/**
- * @brief crypto_policy_set_aes_gcm_128_16_auth() sets a crypto
- * policy structure to an AEAD encryption policy.
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_aes_gcm_128_16_auth(&p) sets
- * the crypto_policy_t at location p to use the SRTP default cipher
- * (AES-128 Galois Counter Mode) with 16 octet auth tag.  This
- * policy applies confidentiality and authentication to both the
- * RTP and RTCP packets.
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @return void.
- * 
- */
-void
-crypto_policy_set_aes_gcm_128_16_auth(crypto_policy_t *p);
-
-/**
- * @brief crypto_policy_set_aes_gcm_256_16_auth() sets a crypto
- * policy structure to an AEAD encryption policy
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_aes_gcm_256_16_auth(&p) sets
- * the crypto_policy_t at location p to use the SRTP default cipher
- * (AES-256 Galois Counter Mode) with 16 octet auth tag.  This 
- * policy applies confidentiality and authentication to both the
- * RTP and RTCP packets.
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- *
- * @return void.
- * 
- */
-void
-crypto_policy_set_aes_gcm_256_16_auth(crypto_policy_t *p);
-
-
-/**
- * @brief srtp_dealloc() deallocates storage for an SRTP session
- * context.
- * 
- * The function call srtp_dealloc(s) deallocates storage for the
- * SRTP session context s.  This function should be called no more
- * than one time for each of the contexts allocated by the function
- * srtp_create().
- *
- * @param s is the srtp_t for the session to be deallocated.
- *
- * @return
- *    - err_status_ok             if there no problems.
- *    - err_status_dealloc_fail   a memory deallocation failure occured.
- */
-
-err_status_t
-srtp_dealloc(srtp_t s);
-
-
-/*
- * @brief identifies a particular SRTP profile 
- *
- * An srtp_profile_t enumeration is used to identify a particular SRTP
- * profile (that is, a set of algorithms and parameters).  These
- * profiles are defined in the DTLS-SRTP draft.
- */
-
-typedef enum {
-  srtp_profile_reserved           = 0,
-  srtp_profile_aes128_cm_sha1_80  = 1,
-  srtp_profile_aes128_cm_sha1_32  = 2,
-  srtp_profile_aes256_cm_sha1_80  = 3,
-  srtp_profile_aes256_cm_sha1_32  = 4,
-  srtp_profile_null_sha1_80       = 5,
-  srtp_profile_null_sha1_32       = 6,
-} srtp_profile_t;
-
-
-/**
- * @brief crypto_policy_set_from_profile_for_rtp() sets a crypto policy
- * structure to the appropriate value for RTP based on an srtp_profile_t
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_rtp_default(&policy, profile)
- * sets the crypto_policy_t at location policy to the policy for RTP
- * protection, as defined by the srtp_profile_t profile.
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- * 
- * @return values
- *     - err_status_ok         no problems were encountered
- *     - err_status_bad_param  the profile is not supported 
- * 
- */
-err_status_t
-crypto_policy_set_from_profile_for_rtp(crypto_policy_t *policy, 
-				       srtp_profile_t profile);
-
-
-
-
-/**
- * @brief crypto_policy_set_from_profile_for_rtcp() sets a crypto policy
- * structure to the appropriate value for RTCP based on an srtp_profile_t
- *
- * @param p is a pointer to the policy structure to be set 
- * 
- * The function call crypto_policy_set_rtcp_default(&policy, profile)
- * sets the crypto_policy_t at location policy to the policy for RTCP
- * protection, as defined by the srtp_profile_t profile.
- * 
- * This function is a convenience that helps to avoid dealing directly
- * with the policy data structure.  You are encouraged to initialize
- * policy elements with this function call.  Doing so may allow your
- * code to be forward compatible with later versions of libSRTP that
- * include more elements in the crypto_policy_t datatype.
- * 
- * @return values
- *     - err_status_ok         no problems were encountered
- *     - err_status_bad_param  the profile is not supported 
- * 
- */
-err_status_t
-crypto_policy_set_from_profile_for_rtcp(crypto_policy_t *policy, 
-				       srtp_profile_t profile);
-
-/**
- * @brief returns the master key length for a given SRTP profile
- */
-unsigned int
-srtp_profile_get_master_key_length(srtp_profile_t profile);
-
-
-/**
- * @brief returns the master salt length for a given SRTP profile
- */
-unsigned int
-srtp_profile_get_master_salt_length(srtp_profile_t profile);
-
-/**
- * @brief appends the salt to the key
- *
- * The function call append_salt_to_key(k, klen, s, slen) 
- * copies the string s to the location at klen bytes following
- * the location k.  
- *
- * @warning There must be at least bytes_in_salt + bytes_in_key bytes
- *          available at the location pointed to by key.
- * 
- */
-
-void
-append_salt_to_key(unsigned char *key, unsigned int bytes_in_key,
-		   unsigned char *salt, unsigned int bytes_in_salt);
-
-
-
-/**
- * @}
- */
-
-
-
-/**
- * @defgroup SRTCP Secure RTCP
- * @ingroup  SRTP 
- *
- * @brief Secure RTCP functions are used to protect RTCP traffic.
- *
- * RTCP is the control protocol for RTP.  libSRTP protects RTCP
- * traffic in much the same way as it does RTP traffic.  The function
- * srtp_protect_rtcp() applies cryptographic protections to outbound
- * RTCP packets, and srtp_unprotect_rtcp() verifies the protections on
- * inbound RTCP packets.  
- *
- * A note on the naming convention: srtp_protect_rtcp() has an srtp_t
- * as its first argument, and thus has `srtp_' as its prefix.  The
- * trailing `_rtcp' indicates the protocol on which it acts.  
- * 
- * @{
- */
-
-/**
- * @brief srtp_protect_rtcp() is the Secure RTCP sender-side packet
- * processing function.
- * 
- * The function call srtp_protect_rtcp(ctx, rtp_hdr, len_ptr) applies
- * SRTCP protection to the RTCP packet rtcp_hdr (which has length
- * *len_ptr) using the SRTP session context ctx.  If err_status_ok is
- * returned, then rtp_hdr points to the resulting SRTCP packet and
- * *len_ptr is the number of octets in that packet; otherwise, no
- * assumptions should be made about the value of either data elements.
- * 
- * @warning This function assumes that it can write the authentication
- * tag into the location in memory immediately following the RTCP
- * packet, and assumes that the RTCP packet is aligned on a 32-bit
- * boundary.
- *
- * @warning This function assumes that it can write SRTP_MAX_TRAILER_LEN+4 
- * into the location in memory immediately following the RTCP packet.   
- * Callers MUST ensure that this much writable memory is available in 
- * the buffer that holds the RTCP packet.
- * 
- * @param ctx is the SRTP context to use in processing the packet.
- *
- * @param rtcp_hdr is a pointer to the RTCP packet (before the call); after
- * the function returns, it points to the srtp packet.
- *
- * @param pkt_octet_len is a pointer to the length in octets of the
- * complete RTCP packet (header and body) before the function call,
- * and of the complete SRTCP packet after the call, if err_status_ok
- * was returned.  Otherwise, the value of the data to which it points
- * is undefined.
- *
- * @return 
- *    - err_status_ok            if there were no problems.
- *    - [other]                  if there was a failure in 
- *                               the cryptographic mechanisms.
- */
-	     
-
-err_status_t 
-srtp_protect_rtcp(srtp_t ctx, void *rtcp_hdr, int *pkt_octet_len);
-
-/**
- * @brief srtp_unprotect_rtcp() is the Secure RTCP receiver-side packet
- * processing function.
- *
- * The function call srtp_unprotect_rtcp(ctx, srtp_hdr, len_ptr)
- * verifies the Secure RTCP protection of the SRTCP packet pointed to
- * by srtcp_hdr (which has length *len_ptr), using the SRTP session
- * context ctx.  If err_status_ok is returned, then srtcp_hdr points
- * to the resulting RTCP packet and *len_ptr is the number of octets
- * in that packet; otherwise, no assumptions should be made about the
- * value of either data elements.
- * 
- * @warning This function assumes that the SRTCP packet is aligned on a
- * 32-bit boundary.
- *
- * @param ctx is a pointer to the srtp_t which applies to the
- * particular packet.
- *
- * @param srtcp_hdr is a pointer to the header of the SRTCP packet
- * (before the call).  After the function returns, it points to the
- * rtp packet if err_status_ok was returned; otherwise, the value of
- * the data to which it points is undefined.
- *
- * @param pkt_octet_len is a pointer to the length in octets of the
- * complete SRTCP packet (header and body) before the function call,
- * and of the complete rtp packet after the call, if err_status_ok was
- * returned.  Otherwise, the value of the data to which it points is
- * undefined.
- *
- * @return 
- *    - err_status_ok          if the RTCP packet is valid.
- *    - err_status_auth_fail   if the SRTCP packet failed the message 
- *                             authentication check.
- *    - err_status_replay_fail if the SRTCP packet is a replay (e.g. has
- *                             already been processed and accepted).
- *    - [other]  if there has been an error in the cryptographic mechanisms.
- *
- */
-
-err_status_t 
-srtp_unprotect_rtcp(srtp_t ctx, void *srtcp_hdr, int *pkt_octet_len);
-
-/**
- * @}
- */
-
-
-/**
- * @defgroup User data associated to a SRTP session.
- * @ingroup  SRTP
- *
- * @brief Store custom user data within a SRTP session.
- *
- * @{
- */
-
-/**
- * @brief srtp_set_user_data() stores the given pointer into the SRTP
- * session for later retrieval.
- *
- * @param ctx is the srtp_t context in which the given data pointer is
- * stored.
- *
- * @param data is a pointer to the custom information (struct, function,
- * etc) associated with the SRTP session.
- *
- * @return void.
- *
- */
-
-void
-srtp_set_user_data(srtp_t ctx, void *data);
-
-/**
- * @brief srtp_get_user_data() retrieves the pointer to the custom data
- * previously stored with srtp_set_user_data().
- *
- * This function is mostly useful for retrieving data associated to a
- * SRTP session when an event fires. The user can then get such a custom
- * data by calling this function with the session field of the
- * srtp_event_data_t struct as argument.
- *
- * @param ctx is the srtp_t context in which the given data pointer was
- * stored.
- *
- * @return void* pointer to the user data.
- *
- */
-
-void*
-srtp_get_user_data(srtp_t ctx);
-
-/**
- * @}
- */
-
-
-/**
- * @defgroup SRTPevents SRTP events and callbacks
- * @ingroup  SRTP
- *
- * @brief libSRTP can use a user-provided callback function to 
- * handle events.
- *
- * 
- * libSRTP allows a user to provide a callback function to handle
- * events that need to be dealt with outside of the data plane (see
- * the enum srtp_event_t for a description of these events).  Dealing
- * with these events is not a strict necessity; they are not
- * security-critical, but the application may suffer if they are not
- * handled.  The function srtp_set_event_handler() is used to provide
- * the callback function.
- *
- * A default event handler that merely reports on the events as they
- * happen is included.  It is also possible to set the event handler
- * function to NULL, in which case all events will just be silently
- * ignored.
- *
- * @{
- */
-
-/**
- * @brief srtp_event_t defines events that need to be handled
- *
- * The enum srtp_event_t defines events that need to be handled
- * outside the `data plane', such as SSRC collisions and 
- * key expirations.  
- *
- * When a key expires or the maximum number of packets has been
- * reached, an SRTP stream will enter an `expired' state in which no
- * more packets can be protected or unprotected.  When this happens,
- * it is likely that you will want to either deallocate the stream
- * (using srtp_stream_dealloc()), and possibly allocate a new one.
- *
- * When an SRTP stream expires, the other streams in the same session
- * are unaffected, unless key sharing is used by that stream.  In the
- * latter case, all of the streams in the session will expire.
- */
-
-typedef enum { 
-  event_ssrc_collision,    /**<
-			    * An SSRC collision occured.             
-			    */
-  event_key_soft_limit,    /**< An SRTP stream reached the soft key
-			    *   usage limit and will expire soon.	   
-			    */
-  event_key_hard_limit,    /**< An SRTP stream reached the hard 
-			    *   key usage limit and has expired.
-			    */
-  event_packet_index_limit /**< An SRTP stream reached the hard 
-			    * packet limit (2^48 packets).             
-			    */
-} srtp_event_t;
-
-/**
- * @brief srtp_event_data_t is the structure passed as a callback to 
- * the event handler function
- *
- * The struct srtp_event_data_t holds the data passed to the event
- * handler function.  
- */
-
-typedef struct srtp_event_data_t {
-  srtp_t        session;  /**< The session in which the event happend. */
-  srtp_stream_t stream;   /**< The stream in which the event happend.  */
-  srtp_event_t  event;    /**< An enum indicating the type of event.   */
-} srtp_event_data_t;
-
-/**
- * @brief srtp_event_handler_func_t is the function prototype for
- * the event handler.
- *
- * The typedef srtp_event_handler_func_t is the prototype for the
- * event handler function.  It has as its only argument an
- * srtp_event_data_t which describes the event that needs to be handled.
- * There can only be a single, global handler for all events in
- * libSRTP.
- */
-
-typedef void (srtp_event_handler_func_t)(srtp_event_data_t *data);
-
-/**
- * @brief sets the event handler to the function supplied by the caller.
- * 
- * The function call srtp_install_event_handler(func) sets the event
- * handler function to the value func.  The value NULL is acceptable
- * as an argument; in this case, events will be ignored rather than
- * handled.
- *
- * @param func is a pointer to a fuction that takes an srtp_event_data_t
- *             pointer as an argument and returns void.  This function
- *             will be used by libSRTP to handle events.
- */
-
-err_status_t
-srtp_install_event_handler(srtp_event_handler_func_t func);
-
-/**
- * @brief Returns the version string of the library. 
- * 
- */
-const char *srtp_get_version_string(void);
-
-/**
- * @brief Returns the numeric representation of the library version. 
- * 
- */
-unsigned int srtp_get_version(void);
-
-/**
- * @}
- */
-/* in host order, so outside the #if */
-#define SRTCP_E_BIT      0x80000000
-/* for byte-access */
-#define SRTCP_E_BYTE_BIT 0x80
-#define SRTCP_INDEX_MASK 0x7fffffff
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* SRTP_H */