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No, it doesn't work this way. CPU has various modes that are typically switched when booting. It could allow to control it before the system boot without forgo

by takeda 9y ago

No, it doesn't work this way. CPU has various modes that are typically switched when booting. It could allow to control it before the system boot without forgoing security. Unless... that "security" is from the users that own it.

illumin8 9y ago
The security also needs to protect against an attacker that has physical access to the device. This is necessary to prevent things like extracting encryption keys.
- takeda 9y ago
  One of things I was taught is that you can't really protect if there is a physical access. Yes, you can make it harder, but that's pretty much it. That's why anyone who is serious have multiple layers of security. Take for example Google data centers, you need access to enter the facility and access to whatever you supposed to work. There are security guards which will follow and stay with you while you are performing your work. The mechanisms in the CPUs are there to protect CPUs from their users. Let say again you are a Google and are planning to use this technology. Why would you trust a third party to decide (by signing) what can run and cannot run on the CPU. What if that 3rd party happens to be your competitor. The issue is that person/company who owns the CPU doesn't have full control over it, they can't load their own certificates and use them for signing. They need to trust 3rd party with it.
euyyn 9y ago
From someone that doesn't know anything about this: Is it impossible for malware to modify that boot code?
- bryanbuckley 9y ago
  Obviously not. Except when it can. (joke..) You can google around for secure boot, trusted boot, chain of trust, etc. Breaking secure boot is the biggest vulnerability a device can experience (e.g. Apple will pay you the most money for this type of break).
- takeda 9y ago
  Yes, that's why things like UEFI were invented to secure the hardware. Those things are not necessarily bad, the problem is with having control over what your computer runs. It's about whether you decide that or a 3rd party that you might not necessarily trust. If things are modifiable before the machine boots, and can't be modified once system has booted, then malware should not be able to modify it.

by takeda 9y ago

illumin8 9y ago

The security also needs to protect against an attacker that has physical access to the device. This is necessary to prevent things like extracting encryption keys.

takeda 9y ago
One of things I was taught is that you can't really protect if there is a physical access. Yes, you can make it harder, but that's pretty much it. That's why anyone who is serious have multiple layers of security. Take for example Google data centers, you need access to enter the facility and access to whatever you supposed to work. There are security guards which will follow and stay with you while you are performing your work. The mechanisms in the CPUs are there to protect CPUs from their users. Let say again you are a Google and are planning to use this technology. Why would you trust a third party to decide (by signing) what can run and cannot run on the CPU. What if that 3rd party happens to be your competitor. The issue is that person/company who owns the CPU doesn't have full control over it, they can't load their own certificates and use them for signing. They need to trust 3rd party with it.

euyyn 9y ago

From someone that doesn't know anything about this: Is it impossible for malware to modify that boot code?

bryanbuckley 9y ago
Obviously not. Except when it can. (joke..) You can google around for secure boot, trusted boot, chain of trust, etc. Breaking secure boot is the biggest vulnerability a device can experience (e.g. Apple will pay you the most money for this type of break).
takeda 9y ago
Yes, that's why things like UEFI were invented to secure the hardware. Those things are not necessarily bad, the problem is with having control over what your computer runs. It's about whether you decide that or a 3rd party that you might not necessarily trust. If things are modifiable before the machine boots, and can't be modified once system has booted, then malware should not be able to modify it.