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106 lines
4.2 KiB
106 lines
4.2 KiB
SEMS
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* [1]Main Page
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* [2]Related Pages
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* [3]Namespaces
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* [4]Data Structures
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* [5]Files
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* [6]Directories
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* [7]Examples
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ZRTP encryption
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Introduction
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ZRTP is a key agreement protocol to negotiate the keys for encryption
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of RTP in phone calls. It is an [8]informational RFC - RFC6189 ZRTP:
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Media Path Key Agreement for Unicast Secure RTP.
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Even though it uses public key encryption, a PKI is not needed. Since
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the keys are negotiated in the media path, support for it in signaling
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is not necessary. ZRTP also offers opportunistic encryption, which
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means that calls between UAs that support it are encrypted, but calls
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to UAs not supporting it are still possible, but unencrypted. The
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actual RTP encryption is done with [9]SRTP.
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ZRTP is one of the widest (if not the widest) supported end-to-end
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encryption methods for VoIP. Popular SIP clients that support ZRTP are
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[10]Jitsi, CSipSimple, Twinkle, Linphone.
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For more information about ZRTP, see the [11]Zfone project, the [12]RFC
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and the [13]wikipedia article.
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ZRTP in SEMS
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Since the version 1.0 SEMS supports ZRTP with the use of the [14]Zfone
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SDK.
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Currrently, the newest version of the ZRTP SDK, and the one that works
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with SEMS, is available at [15]https://github.com/traviscross/libzrtp.
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To build SEMS with ZRTP support, install the SDK and set WITH_ZRTP=yes
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in Makefile.defs, or build with
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$ make WITH_ZRTP=yes
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The conference application is enabled to tell the caller the SAS phrase
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if it is compiled with WITH_SAS_TTS option, set in
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apps/conference/Makefile. For this to work, the [16]flite
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text-to-speech synthesizer version 1.2 or 1.3 is needed.
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How to use ZRTP in your application
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Have a look at the conference application on how to add ZRTP support in
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your application. There is a void AmSession::onZRTPEvent(zrtp_event_t
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event, zrtp_stream_ctx_t *stream_ctx) event that is called with the
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appropriate ZRTP event type and the zrtp stream context, if the state
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of the ZRTP encryption changes. The zrtp_event are defined in the Zfone
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SDK, e.g. ZRTP_EVENT_IS_SECURE.
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Licensing
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The Zfone SDK is licensed under the Affero GPL v3. As SEMS is licensed
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under GPL 2+, you may use SEMS under GPLv3 and link with libZRTP under
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Affero GPL v3. You may use the resulting program under the restrictions
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of both GPLv3 and AGPLv3.
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Note that due to the nature of the GPL, without written consent of the
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authors of SEMS as with any other non-free library, it is not possible
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to distribute SEMS linked to specially licensed commercial version of
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the libZRTP SDK, nor the AGPL version. If in doubt, talk to your
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lawyer.
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Phones with ZRTP
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* [17]Zfone turns every softphone into a secure phone by tapping into
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the RTP sent and received
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* [18]Jitsi
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* [19]Twinkle is a very good free softphone for Linux. It can speak
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ZRTP with the use of GNU [20]libzrtpcpp.
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__________________________________________________________________
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Generated by [21] doxygen 1.7.6.1
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References
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1. file://localhost/home/stefan_plain/devel/sems/zrtp/sems/doc/doxygen_doc/html/index.html
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2. file://localhost/home/stefan_plain/devel/sems/zrtp/sems/doc/doxygen_doc/html/pages.html
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3. file://localhost/home/stefan_plain/devel/sems/zrtp/sems/doc/doxygen_doc/html/namespaces.html
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4. file://localhost/home/stefan_plain/devel/sems/zrtp/sems/doc/doxygen_doc/html/annotated.html
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5. file://localhost/home/stefan_plain/devel/sems/zrtp/sems/doc/doxygen_doc/html/files.html
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6. file://localhost/home/stefan_plain/devel/sems/zrtp/sems/doc/doxygen_doc/html/dirs.html
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7. file://localhost/home/stefan_plain/devel/sems/zrtp/sems/doc/doxygen_doc/html/examples.html
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8. http://tools.ietf.org/html/rfc6189
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9. http://www.ietf.org/rfc/rfc3711.txt
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10. http://www.jitsi.org/
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11. http://zfoneproject.com/
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12. http://tools.ietf.org/html/rfc6189
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13. http://en.wikipedia.org/wiki/ZRTP
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14. http://zfoneproject.com/prod_sdk.html
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15. https://github.com/traviscross/libzrtp
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16. http://cmuflite.org/
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17. http://zfoneproject.com/
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18. http://www.jitsi.org/
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19. http://twinklephone.com/
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20. http://www.gnutelephony.org/index.php/GNU_ZRTP
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21. http://www.doxygen.org/index.html
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