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> The flip side is the assumption that nobody in their right mind would pay for a chip that could be fully wiped and/or updated by end users. Eh, TPMs are full
by cryptonector 4y ago
> The flip side is the assumption that nobody in their right mind would pay for a chip that could be fully wiped and/or updated by end users.
Eh, TPMs are fully erasable -- well, the seeds that matter anyways, but not the public keys that sign firmware updates. There's a big difference between "fully wiped" in the TPM sense and "updated by end users" if the latter means "with their own code", but the latter is still OK if in the process all key material is lost that could be used to impersonate the original device.
I.e., an SE that users can flash with their own software should be OK provided that there is no way to impersonate the original SE after doing so. I've no idea if that can be the case for SEs, but it definitely could be for TPM-like devices.
- ignaloidas 4y agoFWIW it's a bit of a different game with TPMs than with secure elements in general - imagine how much would it cost a bank in credit card replacement costs if the firmware on them could be erased by anyone, making the card useless. That's not something that should be wipeable.
- cryptonector 4y agoSure, because the bank probably doesn't charge customers for the cost of the replacement card, so customers could get a free smartcard for other purposes. What do these cost nowadays?