10 ms·

Will we still own our data?

by rw 18y ago

ramchip 18y ago
I was kind of worried when I saw "Trusted Computing", but having read the article I don't think there's any DRM-related use for it. It's really just HD encryption.
- tptacek 18y ago
  "Trusted Computing" is a bit of a bugbear; the technology behind it is totally inevitable and fundamentally innocuous. All it's saying is, the OS should be able to extract the promise of a secure channel to the chipset and the hardware. Without that promise, you lose your machine just once to a piece of malware and you can never trust it again.
  - Herring 18y ago
    Only a fool would give up control over his computer because he's afraid of wiping it. You can bet your last dollar that promise will be enforced against you as well.
    - tptacek 18y ago
      Who said anything about "giving up control over your computer"? Do you actually know anything about Trusted Computing, or this just propaganda? The TPM specs are public, the programming interface is public, and if you don't like how your software uses it, write different TPM software. Your problem is with Microsoft, not with hardware security. If you don't like Microsoft, don't run Windows.
  - mindslight 18y ago
    I wouldn't call the idea of physical access not being the highest level (to hardware state) particularly innocuous. From the article - "You can't even sell it [a stolen drive] on eBay". Theft deterrence is nice, but the piles of bricked drives left over from xbox upgrades are disgusting. The same eviction of malware can be achieved through a documented hardware interface to the lowest levels of microcode (say, JTAG). The current problem is not due to openness, but closed CPU microcode.
    - eru 18y ago
      > The same eviction of malware can be achieved through a documented hardware interface to the lowest levels of microcode (say, JTAG). The current problem is not due to openness, but closed CPU microcode. Would you please elaborate?
      - mindslight 18y ago
        kragen's comment hits the nail right on the head. Any software update system suffers from the ability to install a "rootkit" that can emulate the update mechanism itself to ensure its own survival. I was mistaken in thinking that CPU microcode was stored in non-volatile memory on the CPU itself, but the same idea goes for any area in which such rootkits can be installed. The simple solution is to allow easy updating of that base firmware through a dedicated hardware interface. A socketed DIP isn't hip anymore (eww through-hole), but a USB device header on the motherboard would certainly work. I'd feel better about trusted computing technology if one of their design goals wasn't preventing physical "tampering" but instead they provided unfettered access through a debug port. However, it seems like they're aiming for the exact opposite in order to facilitate naive software, theft deterrence, and business model preservation.
        tptacek 18y ago
        Can you explain more about how the TPM facilitates naive software and business model preservation? That's not my experience with it, but maybe you've had a different experience.
        mindslight 18y ago
        Certain restrictions are impossible to encode in protocols where one's computer acts as their agent. For example, it's impossible to restrict the duplication or longevity of a document. Remote attestation restricts what code can be used to run a protocol, and thus enables implementation of such naive rules. I don't currently use remote attestation for anything, but it's a matter of time until some bozo decides that remote attestation is the way to solve online banking security ("if only we could be sure they weren't running malware!"), and brings the technology stack mainstream. When that happens, the non-techies (seeing no distinction) will enforce their business rules on end user's computers (they occasionally try to do this now, but run up against reality). Client-side-only verification of form fields may be laughable now, but won't be so funny with no incentive to fix it because common people cannot exploit it.
  - kragen 18y ago
    Maybe it would be better if the machine's owner could extract that secure channel, rather than the OS. For example, if you could reflash the BIOS with a JTAG header on the motherboard, then you could be sure that no compromised BIOS code survived (unless your JTAG programmer was broken). Or you could have a boot monitor in non-Flash ROM that could checksum the Flash BIOS, and then you could compare the checksum to the version before the malware ran, and pop the Flash chip out of its socket to replace it if necessary. Does that answer the threat model you're thinking of? A lot of the stuff under the "Trusted Computing" rubric goes a lot further than what you're describing. Some of it is designed to allow third parties (other than the OS and the machine's owner) to establish a secure channel to the chipset and the hardware over the network. That is almost certainly a bad idea.
    - tptacek 18y ago
      The "secure channel to the chipset over the network" is just a public key pair in a chip. You can use it however you want, or not use it at all. There's no system built in to the TPM that allows your chipset to go talk to Microsoft without your permission. Obviously, if you give Microsoft permission to own your machine, it can go talk to Microsoft.com anytime it wants. But it already could without the TPM.
      - kragen 18y ago
        A public-key pair in a chip is way overkill for the threat model I was talking about. Is it the same threat model you were talking about? You didn't answer that question. And while it's perhaps necessary and desirable that our machines contain tamper-resistant chips with public-key pairs in them, it's neither necessary nor desirable that the private key be secret from the machine's legitimate owner, which is part of the TCG scheme.
        tptacek 18y ago
        The key isn't kept secret from the machine's legitimate owner, Kragen. For instance, TPM keys need to be migratable. Do you spend a lot of time working with TPM/TCG technology? I don't want to sound patronizing; maybe it's me that's missing something.

Will we still own our data?

by rw 18y ago

Will we still own our data?

I was kind of worried when I saw "Trusted Computing", but having read the article I don't think there's any DRM-related use for it. It's really just HD encryption.

tptacek 18y ago
"Trusted Computing" is a bit of a bugbear; the technology behind it is totally inevitable and fundamentally innocuous. All it's saying is, the OS should be able to extract the promise of a secure channel to the chipset and the hardware. Without that promise, you lose your machine just once to a piece of malware and you can never trust it again.
- Herring 18y ago
  Only a fool would give up control over his computer because he's afraid of wiping it. You can bet your last dollar that promise will be enforced against you as well.
  - tptacek 18y ago
    Who said anything about "giving up control over your computer"? Do you actually know anything about Trusted Computing, or this just propaganda? The TPM specs are public, the programming interface is public, and if you don't like how your software uses it, write different TPM software. Your problem is with Microsoft, not with hardware security. If you don't like Microsoft, don't run Windows.
- mindslight 18y ago
  I wouldn't call the idea of physical access not being the highest level (to hardware state) particularly innocuous. From the article - "You can't even sell it [a stolen drive] on eBay". Theft deterrence is nice, but the piles of bricked drives left over from xbox upgrades are disgusting. The same eviction of malware can be achieved through a documented hardware interface to the lowest levels of microcode (say, JTAG). The current problem is not due to openness, but closed CPU microcode.
  - eru 18y ago
    > The same eviction of malware can be achieved through a documented hardware interface to the lowest levels of microcode (say, JTAG). The current problem is not due to openness, but closed CPU microcode. Would you please elaborate?
    - mindslight 18y ago
      kragen's comment hits the nail right on the head. Any software update system suffers from the ability to install a "rootkit" that can emulate the update mechanism itself to ensure its own survival. I was mistaken in thinking that CPU microcode was stored in non-volatile memory on the CPU itself, but the same idea goes for any area in which such rootkits can be installed. The simple solution is to allow easy updating of that base firmware through a dedicated hardware interface. A socketed DIP isn't hip anymore (eww through-hole), but a USB device header on the motherboard would certainly work. I'd feel better about trusted computing technology if one of their design goals wasn't preventing physical "tampering" but instead they provided unfettered access through a debug port. However, it seems like they're aiming for the exact opposite in order to facilitate naive software, theft deterrence, and business model preservation.
      - tptacek 18y ago
        Can you explain more about how the TPM facilitates naive software and business model preservation? That's not my experience with it, but maybe you've had a different experience.
        mindslight 18y ago
        Certain restrictions are impossible to encode in protocols where one's computer acts as their agent. For example, it's impossible to restrict the duplication or longevity of a document. Remote attestation restricts what code can be used to run a protocol, and thus enables implementation of such naive rules. I don't currently use remote attestation for anything, but it's a matter of time until some bozo decides that remote attestation is the way to solve online banking security ("if only we could be sure they weren't running malware!"), and brings the technology stack mainstream. When that happens, the non-techies (seeing no distinction) will enforce their business rules on end user's computers (they occasionally try to do this now, but run up against reality). Client-side-only verification of form fields may be laughable now, but won't be so funny with no incentive to fix it because common people cannot exploit it.
- kragen 18y ago
  Maybe it would be better if the machine's owner could extract that secure channel, rather than the OS. For example, if you could reflash the BIOS with a JTAG header on the motherboard, then you could be sure that no compromised BIOS code survived (unless your JTAG programmer was broken). Or you could have a boot monitor in non-Flash ROM that could checksum the Flash BIOS, and then you could compare the checksum to the version before the malware ran, and pop the Flash chip out of its socket to replace it if necessary. Does that answer the threat model you're thinking of? A lot of the stuff under the "Trusted Computing" rubric goes a lot further than what you're describing. Some of it is designed to allow third parties (other than the OS and the machine's owner) to establish a secure channel to the chipset and the hardware over the network. That is almost certainly a bad idea.
  - tptacek 18y ago
    The "secure channel to the chipset over the network" is just a public key pair in a chip. You can use it however you want, or not use it at all. There's no system built in to the TPM that allows your chipset to go talk to Microsoft without your permission. Obviously, if you give Microsoft permission to own your machine, it can go talk to Microsoft.com anytime it wants. But it already could without the TPM.
    - kragen 18y ago
      A public-key pair in a chip is way overkill for the threat model I was talking about. Is it the same threat model you were talking about? You didn't answer that question. And while it's perhaps necessary and desirable that our machines contain tamper-resistant chips with public-key pairs in them, it's neither necessary nor desirable that the private key be secret from the machine's legitimate owner, which is part of the TCG scheme.
      - tptacek 18y ago
        The key isn't kept secret from the machine's legitimate owner, Kragen. For instance, TPM keys need to be migratable. Do you spend a lot of time working with TPM/TCG technology? I don't want to sound patronizing; maybe it's me that's missing something.