H.235 Control Channel

Euchner Martin Martin.Euchner at MCHP.SIEMENS.DE
Fri Sep 17 10:21:35 EDT 1999


Anseem,

the secure logical channel does not have its own data type. It is merely an abstract notion telling that the OLC operates in a certain mode. It is flagged by KeyProtectionMethod.secureChannel.

The security logical channel is a separate security connection parallel to the unprotected OLC; e.g., TLS, SSL,... The security logical channel is used to establish authentication and exchange key material. This key material is used by the master then as a key encryption key for secure transmission of the media key (within the OLC).

I'm currently preparing an updated version of H.235v2, that will be presented at the upcoming Rapporteurs meeting in October.

Regards,

Martin.

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        -----Original Message-----
        From:   Aseem Agarwal [SMTP:aseem at TRILLIUM.COM]
        Sent:   Friday, September 17, 1999 2:54 AM
        To:     ITU-SG16 at mailbag.cps.intel.com
        Subject:        H.235 Control Channel

        Hi All
          H.235 specifies opening up a secure logical channel. In this mode of
          operation the regular H.245 control channel may operate in unsecured
          mode. I have the following doubts about this procedure:

          1. What is the "DataType" value used in the OpenLogicalChannel message
          exchanged for the secure channel ?

          Section 8.2 specifies that "encryptionData" may be used, but elsewhere
          in the document the channel is referred with the value "h235Control"
          which is yet another value for dataType.

          2. How does the exchange of encryption related information happen on
          the secure logical channel ? Does this happen in the data plane ?
          OR this new logical channel serves as a new control channel and the
          key exchange happens using EncryptionUpdate messages ?

          H.235 does not clearly specify the sematics/functionality of this
          logical channel. IMHO, many loose ends have been left behind which
          may result in different implementations.

          Comments/feedback welcome. Also, please let me know when we can expect
          the updated/next version of H.235 document.

        Regards,
        aseem at trillium.com



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