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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-7D1E2DBD-004B-5047-BDA5-21CD55D0A95C" xml:lang="en"><title>Securing

    13 RTP with SRTP</title><shortdesc>This topic explains how to use callbacks to secure RTP communications. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <p>If you have registered preprocessing and postprocessing callbacks, the

    15 RTP stack calls them when sending or receiving RTP data. Therefore, your application

    16 can implement Secure RTP by adding encryption and authentication steps after

    17 reception and before sending. </p>

    18 <p>Your callback class must derive from MPrePostProcessingCallback and implement

    19 its four methods. Call the <xref href="GUID-97FC8566-E4AD-3881-8669-134798A88779.dita"><apiname>SetPrePostProcessingRegisterCallback(</apiname></xref> method

    20 to register your callbacks. After registration, the callback behaviour is

    21 as follows: </p>

    22 <ul>

    23 <li id="GUID-EC65A889-9113-5095-9E15-42C91E76327B"><p>The RTP stack calls

    24 the appropriate preprocessing callback, <xref href="GUID-97FC8566-E4AD-3881-8669-134798A88779.dita"><apiname>PreRtpProcessing()</apiname></xref> or <xref href="GUID-97FC8566-E4AD-3881-8669-134798A88779.dita"><apiname>PreRtcpProcessing()</apiname></xref>, after data is received

    25 from the socket and before processing RTP headers. </p> </li>

    26 <li id="GUID-B78CDB23-D742-5B70-9F61-0712873EE3B3"><p>The RTP stack calls

    27 the appropriate postprocessing callback, <xref href="GUID-97FC8566-E4AD-3881-8669-134798A88779.dita"><apiname>PostRtpProcessing()</apiname></xref> or <xref href="GUID-97FC8566-E4AD-3881-8669-134798A88779.dita"><apiname>PostRtcpProcessing()</apiname></xref> , after completing an

    28 RTP or RTCP packet and before sending it to the socket. </p> </li>

    29 </ul>

    30 </conbody><related-links>

    31 <link href="GUID-993629CB-17B4-5E87-8DE1-06A4AC473FDD.dita"><linktext>RTP Overview</linktext>

    32 </link>

    33 </related-links></concept>