4 ms·
Don't all TPUs use the same protocol? In any case, a basic sigrok-supported logic analyzer is only another $10.
by puzzlingcaptcha 3y ago
Don't all TPUs use the same protocol? In any case, a basic sigrok-supported logic analyzer is only another $10.
- g_p 3y agoYes, and yes - the LPC bus is standardized, and TPMs need to use the same protocol to enable them to be modules on the motherboard. And yes, it's only $10 or thereabouts for a logic analyzer that can decode LPC bus communications. 2019 ref - https://pulsesecurity.co.nz/articles/TPM-sniffing https://pulsesecurity.co.nz/articles/TPM-sniffing
- michaelt 3y agoSome processors have a 'Firmware TPM' or 'Platform Trust Technology' where the TPM is integrated into the CPU itself, meaning no wires to probe/interpose. RAM, PCIe and USB remain unencrypted though so you can just interpose one of those if you're performing an evil maid attack.
- dist-epoch 3y agoRecent Intel/AMD CPUs feature transparent full memory encryption. Recent AMDs have another feature called SecureBio(metrics) which directly connect one USB socket to the CPU in such a way interception is not possible, which allows one to design a secure USB device (fingerprint reader, webcam for now) which can't be intercepted at the bus level. PCIe is still vulnerable, but I bet it won't be long before transparent encryption comes to it.
- jeroenhd 3y agoMany of them use LPC, but LPC isn't the only protocol used, as I found out in my attempts to find a TPM for my desktop.