4 ms·

> the owner of the PC does not retain absolute control over this device. This is a bit FUD-y. TPMs are key stores, the same as what Apple calls a "secure encla

> the owner of the PC does not retain absolute control over this device. This is a bit FUD-y. TPMs are key stores, the same as what Apple calls a "secure enclave." When you activate a device with a service like Netflix or a software like Windows, they stick their key in the TPM. As a user you can clear of disconnect the TPM any time you like - you're in control of your device. What you're not in control of is Netflix and Windows - Netflix and Windows are only going to authorize 5 TPMs. If you reset your TPM, you're going to need to re-enter your license information.

josephcsible 5y ago
The fact that, by design, you (the owner) can't make the TPM give you all of its secret keys, means that you don't have control over your device.
- will4274 5y ago
  Does it? I can't make my microwave work with the door open either. The whole "point" of a TPM is that the user can create, use, and delete keys inside of it, with the promise that the keys won't come out. TPMs are just smart cards. Would you say that you don't have control over a smart card because you can't get the keys out of it? I'd say I DO have control over the smartcard, because I authorize and de-authorize the keys held within, and the whole point of a smartcard is to permit authorization of a physical entity, which requires the physical entity to resist leaking its keys. To me, operating with a well designed model, when and if I choose, with the ability for me to shut it down at any time - that's control.
  - josephcsible 5y ago
    In an ideal world, all smart cards/TPMs/HSMs would have these two properties: 1. Under no circumstances would they ever be sold with any private keys already on them 2. There would be no way to prove or determine after the fact whether a given key was generated internally or imported from an external source If those two things were true, then you'd still be able to get 100% of the legitimate security benefit of them, but they'd be completely unusable for DRM and other evil things.

josephcsible 5y ago

The fact that, by design, you (the owner) can't make the TPM give you all of its secret keys, means that you don't have control over your device.

will4274 5y ago
Does it? I can't make my microwave work with the door open either. The whole "point" of a TPM is that the user can create, use, and delete keys inside of it, with the promise that the keys won't come out. TPMs are just smart cards. Would you say that you don't have control over a smart card because you can't get the keys out of it? I'd say I DO have control over the smartcard, because I authorize and de-authorize the keys held within, and the whole point of a smartcard is to permit authorization of a physical entity, which requires the physical entity to resist leaking its keys. To me, operating with a well designed model, when and if I choose, with the ability for me to shut it down at any time - that's control.
- josephcsible 5y ago
  In an ideal world, all smart cards/TPMs/HSMs would have these two properties: 1. Under no circumstances would they ever be sold with any private keys already on them 2. There would be no way to prove or determine after the fact whether a given key was generated internally or imported from an external source If those two things were true, then you'd still be able to get 100% of the legitimate security benefit of them, but they'd be completely unusable for DRM and other evil things.