On Mon, 25 Jun 2007, Hal Finney wrote: > The idea of putting a TPM on a smart card or other removable device is > even more questionable from this perspective. A TPM which communicates > via an easily accessible and tamperable bus is almost useless for the > security concepts behind the Trusted Computing Group architecture.
Even if a TPM is soldered to the motherboard it does not mean that unsoldering is an esoteric art. There is a difference between what media hypes about TPM and what TCG technical documents say [1]: It is not expected that a TPM will be able to defeat sophisticated physical attacks. > The exception might be if there were additional hardware to encrypt > the bus, but that is not part of the standard spec. Encrypted bus requires encryption cores on both ends and key distribution resistant to MitM attacks. I suspect that if you system already has so many crypto blocks in it, it would be cheaper to implement TPM inside. > So this would allow a removable TPM but it has to be "logically" bound > to the motherboard via cryptography, presumably something like an > encrypted bus. To logically bound TPM to the motherboard it is enough for BIOS `loader' that hashes the rest of the BIOS, to include unique ID of the motherboard into the hash. [1] <https://www.trustedcomputinggroup.org/groups/tpm/TPM_1_2_Changes_final.pdf> -- Regards, ASK --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]