On: TPM Sniffing

[brokenmachine]

This is complete speculation, but it could be like TLS.

That would make it much harder as you'd have to MITM the communication, not just sniff it. Maybe impossible to decrypt if both the TPM and the chip it's communicating with use keys signed by the manufacturer.

[cryptonector → brokenmachine]

I might ask "why speculate when you can go find out?", but in this case finding out is non-trivial. See above for an explanation though.

[brokenmachine → cryptonector]

Your comment wasn't there when I speculated.

Sounds pretty similar to TLS to me, in my non-expert opinion.

[tinus_hn → brokenmachine]

I think the difference with TLS is that, in the attacks the TPM should protect you from, the attacker controls the client and the network.

I don’t really see how it is possible to defend against that. But I don’t quite understand how the TPM checks what the CPU is doing either.

[brokenmachine → tinus_hn]

Disclaimer: I'm not an expert. At all.

I don't think it checks what the CPU is doing at all. It just makes software able to check if the platform is signed by the manufacturer.

The way I understand it is that the keys are burned into the TPM at time of manufacture, and there is no way to extract those keys, software can only ask the TPM to encrypt/decrypt/sign/verify certain data using the keys.

The TPM can then be used to verify certain operations, eg to retrieve the key for an encrypted hard drive.

But it's all a trojan horse because the manufacturer is the one who controls the keys, not the user.

It's "trusted" in the sense that the platform is "trusted" by the manufacturer, not the user.