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> In the years since CALEA was passed it has been greatly expanded to include all VoIP and broadband Internet traffic. the article makes it sound like LE is fr
by colinsane 3y ago
> In the years since CALEA was passed it has been greatly expanded to include all VoIP and broadband Internet traffic.
the article makes it sound like LE is freely able to tap any VoIP call. how would that work?
i thought the usual setup for a VoIP call is SIP to ring the other party (which is partially secured), followed by ICE/STUN/TURN for the parties to find the most direct route between them, followed by the actual audio stream. do clients just not encrypt the audio stream? do carriers MITM everything downstream of that first SIP hop? (that would be inconsistent with the read-only probing suggested: “hardware taps or switch/router mirror-ports are employed to deliver copies of all of a network's data to dedicated IP probes.”).
- Nextgrid 3y ago> ICE/STUN/TURN for the parties to find the most direct route between them From my experience, using SIP to interact with the PSTN usually means your first point of entry into the PSTN also proxies the media. > do clients just not encrypt the audio stream? SIP encryption is very uncommon, and unless you use ZRTP (which is end-to-end), I believe any SIP server within the path mediates the key exchange and can thus capture the key or downgrade/disable the encryption. Given the above points, a packet capture on a switch port would give you both signalling and media traffic and is most likely how SIP lawful intercept is implemented.