Krishna,

It is true that there is a way to decrypt SSL/TLS in wireshark, and to 
write a dissector that can handle a protocol that's tunneled through 
SSL/TLS. If you're writing a dissector that will look at the voip 
traffic, here's generally what you'd do:

* One of the two connections in the SSL tunnel needs to be using a 
static key, and you need a copy of this key.
* In wireshark, click Edit -> Preferences -> Protocols -> SSL
* A field on this screen (name escapes me) takes a parameter formatted 
like this:
<ip>,<port>,<protocol>,<path>
... where <ip> and <port> are the ip of the server whose private keyfile 
you have, <port> is the port you want to dissect on, <protocol> is the 
protocol you expect to get out of the SSL/TLS traffic (for example, if 
the traffic you're wanting to examine rides on top of http, you'd want 
to put the string http in place of <protocol>, then have your dissector 
look at http traffic to determine whether your dissector can handle it. 
Alternatively, you'd put the protocol name of your dissector if you want 
to directly handle the unencrypted payload). Finally, <path> is the path 
to your keyfile. In *nix, I believe the field seperator is ; instead of ,
* Once you have it working, you'd then need a dissector to handle the 
traffic you want to examine. This is where your own coding skills come 
into play. There may be a voip dissector already, but I don't have the 
latest wireshark build on this computer to check.

-Brian

[EMAIL PROTECTED] wrote:
>
> Hi,
>
> I’m doing a study project on Voip security using TLS. We can send 
> H.323 messages in an encrypted TLS tunnel. To debug these messages we 
> need a plug-in in Wireshark which actually decrypts the TLS and the 
> tunneled messages. However, I guess it is not so easy to decrypt the 
> data sent in the TLS tunnel.
>
> I heard that there is Lawful Interception services with which can 
> get/trace the keys exchanged during TLS handshake and use the keys for 
> further decryption of data may be by feeding the key to TLS plug-in or 
> so.
>
> Does Wireshark have support for this kind of functionality?
>
> Can any one help me in giving more details and information in this area?
>
> Regards,
>
> Krishna .
>
>
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