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<task id="GUID-372B7A9F-261E-5F3F-B114-4BE2FE2EF7C7" xml:lang="en"><title>Creating
a SRTP Stream</title><abstract><p>SRTP library generates SRTP packets from the RTP or RTCP stream
and forwards the packets to the receiver. SRTP transforms incoming SRTP packets
to RTP/RTCP packets and passes them up the stack.  </p><p> The cryptographic
state information associated with each SRTP stream is termed the cryptographic
context. The state information is maintained by both the sender and receiver
of SRTP streams. If multiple SRTP streams exist within a given RTP session,
then separate cryptographic contexts must be maintained for each stream. Each
stream is identified by a Synchronisation Source (SSRC). The stream can be
a incoming or outgoing.  </p></abstract><prolog><metadata><keywords/></metadata></prolog><taskbody>
<prereq><p>Prior to stream creation: </p> <ul>
<li id="GUID-A5BAEFAD-4D7E-55E8-8C7E-6D0050E4EA51"><p>A SRTP session must
be created and initialised. </p> </li>
<li id="GUID-D39A619E-3302-555C-BA48-437438E87A90"><p>Values to populate the
cryptographic context for the stream shall be available. </p> <p>The callback
object (for MSRTPReKeyingObserver) shall be implemented . </p> </li>
</ul> </prereq>
<steps id="GUID-CABD5696-FCB4-57FD-953D-2DCB97FF7021">
<step id="GUID-D9014EE0-7D97-5C29-B37E-E09E1A421705"><cmd>Create a SRTP stream
(incoming) by invoking the <xref href="GUID-86044C21-B6E7-3A38-AEA1-DC1DF372DAAE.dita"><apiname>NewL()</apiname></xref> of
the class <xref href="GUID-86044C21-B6E7-3A38-AEA1-DC1DF372DAAE.dita"><apiname>CSRTPStreamIn</apiname></xref>. </cmd>

<info>The functions <xref href="GUID-86044C21-B6E7-3A38-AEA1-DC1DF372DAAE.dita"><apiname>NewL()</apiname></xref> has six
variants. Each of the variants are explained below. </info>
<substeps id="GUID-F852D7E8-4434-53DF-92F5-DEE5EEB5A009">
<substep id="GUID-CF0C39A0-E813-5FEA-91FE-8548F74559B8"><cmd/>
<stepxmp><codeblock id="GUID-5E7C4FF4-FBBB-5B31-AC1E-F1CDE07152E8" xml:space="preserve">
                     IMPORT_C static CSRTPStreamIn* NewL( CSRTPSession&amp; aSession,
                                      TUint aSSRC);</codeblock> </stepxmp>

<info>This API is appropriate when the stream uses the cryptographic context
of the session. </info>
<stepxmp>aSession is the input parameter that contains the session. The stream
will use the cryptographic context of the session. </stepxmp>
<stepxmp>aSSRC is the input parameter that contains the synchronization source
ID of the SRTP stream. </stepxmp>
<stepresult>The API leaves with KErrNone if successfully executed, else returns
a valid system-wide error code. </stepresult>
</substep>
<substep id="GUID-685A0114-7E49-5F44-BA72-D012D9F949D7"><cmd/>
<stepxmp><codeblock id="GUID-AD168026-EC51-5685-8C8E-A8C3968DB47B" xml:space="preserve">
                     IMPORT_C static CSRTPStreamIn* NewL( CSRTPSession&amp; aSession,
                                      TUint aSSRC,
                                      CSRTPCryptoContext* aCon,
                                      MSRTPReKeyingObserver&amp; aObs );</codeblock> </stepxmp>

<info>This API is appropriate when the stream will have a cryptographic context
of its own. </info>
<stepxmp>aSession is the input parameter that contains the session. </stepxmp>
<stepxmp>aSSRC is the input parameter that contains the synchronization source
ID of the SRTP stream. </stepxmp>
<stepxmp>aCon is the input parameter that contains cryptographic context of
the SRTP stream. </stepxmp>
<stepxmp>aObs is the callback object. </stepxmp>
<stepresult>The API leaves with KErrNone if successfully executed, else returns
a valid system-wide error code. </stepresult>
</substep>
<substep id="GUID-160B8669-5CC2-5B80-9639-8FC80493A4C6"><cmd/>
<stepxmp><codeblock id="GUID-91CB350B-6572-5250-A08C-A1150CB59468" xml:space="preserve">
                     IMPORT_C static CSRTPStreamIn* NewL( CSRTPSession&amp; aSession);</codeblock> </stepxmp>

<info>This API is appropriate when the stream will use the cryptographic context
of the session. No synchronisation source id is provided at the time of stream
creation. The stream uses late binding. </info>
<stepxmp>aSession is the input parameter that contains the session. </stepxmp>
<stepresult>The API leaves with KErrNone if successfully executed, else returns
a valid system-wide error code. </stepresult>
</substep>
<substep id="GUID-25FD7761-7ED8-5435-B772-2C61E2CD36CC"><cmd/>
<stepxmp><codeblock id="GUID-E126672C-D116-5567-9884-8F4D0D7B35E6" xml:space="preserve">
                     IMPORT_C static CSRTPStreamIn* NewL( CSRTPSession&amp; aSession,
                                      CSRTPCryptoContext* aCon,
                                      MSRTPReKeyingObserver&amp; aObs );</codeblock> </stepxmp>

<info>This API is appropriate when the stream will have a cryptographic context
of its own. No synchronisation source id is provided at the time of stream
creation. The stream uses late binding. </info>
<stepxmp>aSession is the input parameter that contains the session. </stepxmp>
<stepxmp>aCon is the input parameter that contains cryptographic context of
the SRTP stream. </stepxmp>
<stepxmp>aObs is the callback object. </stepxmp>
<stepresult>The API leaves with KErrNone if successfully executed, else returns
a valid system-wide error code. </stepresult>
</substep>
<substep id="GUID-A0CF7B65-9696-5D19-A58F-A9CA9B6C81E3"><cmd/>
<stepxmp><codeblock id="GUID-2120336E-C154-5C64-9D89-E60A486BB062" xml:space="preserve">
                    IMPORT_C static CSRTPStreamIn* NewL( CSRTPSession&amp; aSession,
                                      TUint aSSRC,
                                      MSRTPReKeyingObserver&amp; aObs );</codeblock> </stepxmp>

<info>This API is appropriate when the stream will have a cryptographic context
of its own. The cryptographic context is set later using <xref href="GUID-86044C21-B6E7-3A38-AEA1-DC1DF372DAAE.dita"><apiname>SetCryptoInL().</apiname></xref>  </info>
<stepxmp>aSession is the input parameter that contains the session. </stepxmp>
<stepxmp>aSSRC is the input parameter that contains the synchronization source
ID of the SRTP stream. </stepxmp>
<stepxmp>aObs is the callback object. </stepxmp>
<stepresult>The API leaves with KErrNone if successfully executed, else returns
a valid system-wide error code. </stepresult>
</substep>
<substep id="GUID-DD5D97B1-9170-5BD9-A484-EF3BD94DD7D3"><cmd/>
<stepxmp><codeblock id="GUID-B99F6769-1B3B-5D5E-B592-231D42960FF3" xml:space="preserve">
                     IMPORT_C static CSRTPStreamIn* NewL( CSRTPSession&amp; aSession,
                                      MSRTPReKeyingObserver&amp; aObs ); </codeblock> </stepxmp>

<info>This API is appropriate when the stream will have a cryptographic context
of its own. The cryptographic context is set later using <xref href="GUID-86044C21-B6E7-3A38-AEA1-DC1DF372DAAE.dita"><apiname>SetCryptoInL().</apiname></xref> No
synchronisation source id is provided at the time of stream creation .The
stream uses late binding. </info>
<stepxmp>aSession is the input parameter that contains the session. </stepxmp>
<stepxmp>aObs is the callback object. </stepxmp>
<stepresult>The API leaves with KErrNone if successfully executed, else returns
a valid system-wide error code. </stepresult>
</substep>
</substeps>
</step>
<step id="GUID-2305B32B-0C0A-561A-8EAC-501DBB246632"><cmd>Create a SRTP stream
(outgoing) by invoking the <xref href="GUID-86044C21-B6E7-3A38-AEA1-DC1DF372DAAE.dita"><apiname>NewL()</apiname></xref> of
the class <xref href="GUID-86044C21-B6E7-3A38-AEA1-DC1DF372DAAE.dita"><apiname>CSRTPStreamOut</apiname></xref>. </cmd>

<info>The functions <xref href="GUID-86044C21-B6E7-3A38-AEA1-DC1DF372DAAE.dita"><apiname>NewL()</apiname></xref> has three
variants. Each of the variants are explained below. </info>
<substeps id="GUID-70902482-3118-5F45-85D1-4D35D82831BD">
<substep id="GUID-5A084F2A-85B7-59F9-8801-831A1B10057E"><cmd/>
<stepxmp><codeblock id="GUID-5BA8A9E3-7BAE-5409-854E-B6840D32C80E" xml:space="preserve">
                     IMPORT_C static CSRTPStreamOut* NewL( CSRTPSession&amp; aSession, TUint aSSRC );</codeblock> </stepxmp>

<info>This API is appropriate when the stream uses the cryptographic context
of the session. </info>
<stepxmp>aSession is the input parameter that contains the session. The stream
will use the cryptographic context of the session. </stepxmp>
<stepxmp>aSSRC is the input parameter that contains the synchronization source
ID of the SRTP stream. </stepxmp>
<stepresult>The API leaves with KErrNone if successfully executed, else returns
a valid system-wide error code. </stepresult>
</substep>
<substep id="GUID-86DC7C26-24BF-5973-8F46-90A716024F27"><cmd/>
<stepxmp><codeblock id="GUID-7E9DCEB2-6A34-5C3E-B944-9C558CCDA2F2" xml:space="preserve">
                     IMPORT_C static CSRTPStreamOut* NewL( CSRTPSession&amp; aSession,
                                       TUint aSSRC,
                                       CSRTPCryptoContext* aCon,
                                       MSRTPReKeyingObserver&amp; aObs );
        </codeblock> </stepxmp>

<info>This API is appropriate when the stream will have a cryptographic context
of its own. </info>
<stepxmp>aSession is the input parameter that contains the session. </stepxmp>
<stepxmp>aSSRC is the input parameter that contains the synchronization source
ID of the SRTP stream. </stepxmp>
<stepxmp>aCon is the input parameter that contains cryptographic context of
the SRTP stream. </stepxmp>
<stepxmp>aObs is the callback object. </stepxmp>
<stepresult>The API leaves with KErrNone if successfully executed, else returns
a valid system-wide error code. </stepresult>
</substep>
<substep id="GUID-08AEA9DC-88BC-56B5-8E6C-51C312875B19"><cmd/>
<stepxmp><codeblock id="GUID-ADDC31FE-6D66-5860-9B1B-ACFF9E9CCCBC" xml:space="preserve">
                    IMPORT_C static CSRTPStreamOut* NewL( CSRTPSession&amp; aSession,
                                       TUint aSSRC,
                                       MSRTPReKeyingObserver&amp; aObs ); </codeblock> </stepxmp>

<info>This API is appropriate when the stream will have a cryptographic context
of its own. The cryptographic context is set later using <xref href="GUID-86044C21-B6E7-3A38-AEA1-DC1DF372DAAE.dita"><apiname>SetCryptoOutL().</apiname></xref>  </info>
<stepxmp>aSession is the input parameter that contains the session. </stepxmp>
<stepxmp>aSSRC is the input parameter that contains the synchronization source
ID of the SRTP stream. </stepxmp>
<stepxmp>aObs is the callback object. </stepxmp>
<stepresult>The API leaves with KErrNone if successfully executed, else returns
a valid system-wide error code. </stepresult>
</substep>
</substeps>
</step>
</steps>
<result><p>On successful execution of the API, a SRTP stream is created and
initialized. </p> </result>
<postreq><p>The cryptographic context of the stream can be deleted and the
stream can be re-initialised using <xref href="GUID-86044C21-B6E7-3A38-AEA1-DC1DF372DAAE.dita"><apiname>UpdateCryptoAndStatesL() </apiname></xref>. </p> </postreq>
</taskbody><related-links>
<link href="GUID-06370120-7738-5694-9A8C-3B5B1E3A4352.dita"><linktext>Creating
an SRTP                 Session</linktext></link>
<link href="GUID-425A208C-5D2D-55FD-8623-9E00006E2781.dita"><linktext>Creating
a                 Cryptographic Context</linktext></link>
<link href="GUID-79846EA2-33CD-5D01-8E96-6092C15BD839.dita"><linktext>Encrypting
                RTCP Packet Data</linktext></link>
<link href="GUID-922F292E-9420-593B-B226-2764C5F29DF9.dita"><linktext>Encrypting
RTP                 Packet Data</linktext></link>
<link href="GUID-6E1AC4C9-7CA3-503A-AFC0-BAF29CCA8290.dita"><linktext>Decrypting
RTP                 Packet Data</linktext></link>
<link href="GUID-F9A24A47-7A0B-5F6E-8B0A-B7A7BCC4EAFC.dita"><linktext>Decrypting
                RTCP Packet Data</linktext></link>
<link href="GUID-B9BD2E0A-F214-5344-91A6-E4E99F0D74C8.dita"><linktext>Updating
Master                 Key</linktext></link>
<link href="GUID-F9A24A47-7A0B-5F6E-8B0A-B7A7BCC4EAFC.dita"><linktext>Managing
                Master Key</linktext></link>
</related-links></task>