jrtplib编译库minGW32+qt

<a name="introduction-to-libsrtp"></a> # Introduction to libSRTP This package provides an implementation of the Secure Real-time Transport Protocol (SRTP), the Universal Security Transform (UST), and a supporting cryptographic kernel. The SRTP API is documented in include/srtp.h, and the library is in libsrtp2.a (after compilation). This document describes libSRTP, the Open Source Secure RTP library from Cisco Systems, Inc. RTP is the Real-time Transport Protocol, an IETF standard for the transport of real-time data such as telephony, audio, and video, defined by [RFC 3550](https://www.ietf.org/rfc/rfc3550.txt). Secure RTP (SRTP) is an RTP profile for providing confidentiality to RTP data and authentication to the RTP header and payload. SRTP is an IETF Standard, defined in [RFC 3711](https://www.ietf.org/rfc/rfc3711.txt), and was developed in the IETF Audio/Video Transport (AVT) Working Group. This library supports all of the mandatory features of SRTP, but not all of the optional features. See the [Supported Features](#supported-features) section for more detailed information. This document is also used to generate the documentation files in the /doc/ folder where a more detailed reference to the libSRTP API and related functions can be created (requires installing doxygen.). The reference material is created automatically from comments embedded in some of the C header files. The documentation is organized into modules in order to improve its clarity. These modules do not directly correspond to files. An underlying cryptographic kernel provides much of the basic functionality of libSRTP but is mostly undocumented because it does its work behind the scenes. -------------------------------------------------------------------------------- <a name="contact"></a> # Contact Us - [libsrtp@lists.packetizer.com](mailto:libsrtp@lists.packetizer.com) general mailing list for news / announcements / discussions. This is an open list, see [https://lists.packetizer.com/mailman/listinfo/libsrtp](https://lists.packetizer.com/mailman/listinfo/libsrtp) for singing up. - [libsrtp-security@lists.packetizer.com](mailto:libsrtp-security@lists.packetizer.com) for disclosing security issues to the libsrtp maintenance team. This is a closed list but anyone can send to it. -------------------------------------------------------------------------------- <a name="contents"></a> ## Contents - [Introduction to libSRTP](#introduction-to-libsrtp) - [Contact Us](#contact) - [Contents](#contents) - [License and Disclaimer](#license-and-disclaimer) - [libSRTP Overview](#libsrtp-overview) - [Secure RTP Background](#secure-rtp-background) - [Supported Features](#supported-features) - [Implementation Notes](#implementation-notes) - [Installing and Building libSRTP](#installing-and-building-libsrtp) - [Applications](#applications) - [Example Code](#example-code) - [Credits](#credits) - [References](#references) -------------------------------------------------------------------------------- <a name="license-and-disclaimer"></a> # License and Disclaimer libSRTP is distributed under the following license, which is included in the source code distribution. It is reproduced in the manual in case you got the library from another source. > 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. -------------------------------------------------------------------------------- <a name="libsrtp-overview"></a> # libSRTP Overview libSRTP provides functions for protecting RTP and RTCP. RTP packets can be encrypted and authenticated (using the `srtp_protect()` function), turning them into SRTP packets. Similarly, SRTP packets can be decrypted and have their authentication verified (using the `srtp_unprotect()` function), turning them into RTP packets. Similar functions apply security to RTCP packets. The typedef `srtp_stream_t` points to a structure holding all of the state associated with an SRTP stream, including the keys and parameters for cipher and message authentication functions and the anti-replay data. A particular `srtp_stream_t` holds the information needed to protect a particular RTP and RTCP stream. This datatype is intentionally opaque in order to better seperate the libSRTP API from its implementation. Within an SRTP session, there can be multiple streams, each originating from a particular sender. Each source uses a distinct stream context to protect the RTP and RTCP stream that it is originating. The typedef `srtp_t` points to a structure holding all of the state associated with an SRTP session. There can be multiple stream contexts associated with a single `srtp_t`. A stream context cannot exist indepent from an `srtp_t`, though of course an `srtp_t` can be created that contains only a single stream context. A device participating in an SRTP session must have a stream context for each source in that session, so that it can process the data that it receives from each sender. In libSRTP, a session is created using the function `srtp_create()`. The policy to be implemented in the session is passed into this function as an `srtp_policy_t` structure. A single one of these structures describes the policy of a single stream. These structures can also be linked together to form an entire session policy. A linked list of `srtp_policy_t` structures is equivalent to a session policy. In such a policy, we refer to a single `srtp_policy_t` as an *element*. An `srtp_policy_t` strucutre contains two `crypto_policy_t` structures that describe the cryptograhic policies for RTP and RTCP, as well as the SRTP master key and the SSRC value. The SSRC describes what to protect (e.g. which stream), and the `crypto_policy_t` structures describe how to protect it. The key is contained in a policy element because it simplifies the interface to the library. In many cases, it is desirable to use the same cryptographic policies across all of the streams in a session, but to use a distinct key for each stream. A `crypto_policy_t` structure can be initialized by using either the `crypto_policy_set_rtp_default()` or `crypto_policy_set_rtcp_default()` functions, which set a crypto policy structure to the default policies for RTP and RTCP protection, respectively. -------------------------------------------------------------------------------- <a name="secure-rtp-background"></a> ## Secure RTP Background In this section we review SRTP and introduce some terms that are used in libSRTP. An RTP session is defined b