5 ms·

So you're going with some open source ARM design then? Because Intel's ME/AMT sure as hell isn't any better.

cyphar 9y ago
ARM has TrustZone. OpenPOWER or RISC-V are the only real options at the moment, and both of them are prohibitively expensive to get hardware for and basically require using a softcore in an FPGA.
- simias 9y ago
  And event then you have to trust the closed source synthesis tools on top of the FPGA itself... Of course it would be harder to backdoor but it's probably doable, especially if it targets those particular designs specifically. There's simply no way to get a completely trusted computer stack nowadays, short of assembling it by hand using discrete electronics. It won't run very fast though... I guess an alternative would be to crowdfund the production of an open source CPU then take a few samples and send them to people with an electron microscope and a lot of patience to make sure that the silicon really matches the design and wasn't tempered with in the fab.
- pedroaraujo 9y ago
  TrustZone is an addon that can be used to implement actual security features into a certain device. It is not attached to ARM's CPUs, not it is mandatory, it is just something that SoC developers can pick up and implement however they want.
  - cyphar 9y ago
    Are there examples of non-TrustZone ARM SoCs? I'm not aware of any, which would make it a moot point about whether a theoretical vendor could make the decision to not includ eit.
    - pedroaraujo 9y ago
      An ARM CPU is hardly comparable to an Intel/AMD CPU. And I don't mean in terms of performance. The CPUs from Intel/AMD are much more than a simple CPU, they are a complete system on a chip with a lot of more features that go beyond processing power for your system. On the other hand, an ARM CPU is just a simple CPU. If you want to make comparisons, a more correct one would be between the Intel/AMD CPUs and a Snapdragon processor.
      - monocasa 9y ago
        ARM chips have been full SoCs for far longer than x86 chips have been. It took a while for Intel and AMD to integrate the memory controllers and PCI root complex onto the CPU rather than in the northbridge. AKAIK, only the Versatile/RealView style boards that an SoC manufacturer would get directly from ARM come with bare ARM chips. Anything other than that is an SoC.
        pedroaraujo 9y ago
        ARM doesn't design SoCs, ARM designs CPUs. My point is that an Intel/AMD product is a complete solution while an ARM product is just the very basic implementation of a CPU. ARM doesn't mandate on anything related to the SoC except for the CPU, everything else related to PCI buses, memories, physical implementation, chipsets, etc, is up to the SoC developer to decide and implement.
    - suihkulokki 9y ago
      The hikey and hikey960 devboards let you build your own code to run in the trustzone - eg the boot chain isn't signed and secure. The trustzone and uefi implemention these boards use is also fully open source.
      - qb45 9y ago
        Maybe we should start with stating that the core of TZ is an execution mode of the ARM CPU privileged above the normal kernel mode, not a separate core running some obscure code. TZ can run any suitable hypervisor or just be left unused. It's nothing like the ME/PSP. Still, some boards/devices may lock it down, for example by code signing.

ARM has TrustZone. OpenPOWER or RISC-V are the only real options at the moment, and both of them are prohibitively expensive to get hardware for and basically require using a softcore in an FPGA.

simias 9y ago
And event then you have to trust the closed source synthesis tools on top of the FPGA itself... Of course it would be harder to backdoor but it's probably doable, especially if it targets those particular designs specifically. There's simply no way to get a completely trusted computer stack nowadays, short of assembling it by hand using discrete electronics. It won't run very fast though... I guess an alternative would be to crowdfund the production of an open source CPU then take a few samples and send them to people with an electron microscope and a lot of patience to make sure that the silicon really matches the design and wasn't tempered with in the fab.
pedroaraujo 9y ago
TrustZone is an addon that can be used to implement actual security features into a certain device. It is not attached to ARM's CPUs, not it is mandatory, it is just something that SoC developers can pick up and implement however they want.
- cyphar 9y ago
  Are there examples of non-TrustZone ARM SoCs? I'm not aware of any, which would make it a moot point about whether a theoretical vendor could make the decision to not includ eit.
  - pedroaraujo 9y ago
    An ARM CPU is hardly comparable to an Intel/AMD CPU. And I don't mean in terms of performance. The CPUs from Intel/AMD are much more than a simple CPU, they are a complete system on a chip with a lot of more features that go beyond processing power for your system. On the other hand, an ARM CPU is just a simple CPU. If you want to make comparisons, a more correct one would be between the Intel/AMD CPUs and a Snapdragon processor.
    - monocasa 9y ago
      ARM chips have been full SoCs for far longer than x86 chips have been. It took a while for Intel and AMD to integrate the memory controllers and PCI root complex onto the CPU rather than in the northbridge. AKAIK, only the Versatile/RealView style boards that an SoC manufacturer would get directly from ARM come with bare ARM chips. Anything other than that is an SoC.
      - pedroaraujo 9y ago
        ARM doesn't design SoCs, ARM designs CPUs. My point is that an Intel/AMD product is a complete solution while an ARM product is just the very basic implementation of a CPU. ARM doesn't mandate on anything related to the SoC except for the CPU, everything else related to PCI buses, memories, physical implementation, chipsets, etc, is up to the SoC developer to decide and implement.
  - suihkulokki 9y ago
    The hikey and hikey960 devboards let you build your own code to run in the trustzone - eg the boot chain isn't signed and secure. The trustzone and uefi implemention these boards use is also fully open source.
    - qb45 9y ago
      Maybe we should start with stating that the core of TZ is an execution mode of the ARM CPU privileged above the normal kernel mode, not a separate core running some obscure code. TZ can run any suitable hypervisor or just be left unused. It's nothing like the ME/PSP. Still, some boards/devices may lock it down, for example by code signing.