Wireshark-dev: Re: [Wireshark-dev] Plugin for Lawful Interception of SSL/TLS messages ...
From: Brian Vandenberg <[email protected]>
Date: Fri, 03 Nov 2006 10:08:46 -0700

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:
... 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.

[email protected] wrote:

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 
Does Wireshark have support for this kind of functionality?

Can any one help me in giving more details and information in this area?


Krishna .

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