I am the author of Loop-Amnesia, a system similar to TRESOR, but more sophisticated in that it supports multiple encrypted volumes. After looking over the article, it does not appear that this is at all similar. It also does not appear to protect against the cold boot attack as claimed.
The authors claim a 2% performance reduction. Such a reduction implies that the instructions are not being decrypted literally on-the-fly; the reduction would be much more severe then. They're using a tactic called a "TLB split", which corrupts the cached page table so that reading memory gets you different results from executing it. A page of executable code is likely decrypted with a key stored in the CPU, put in a different physical page, and then the TLB split is performed so that executes go to the other page while reads still go to the encrypted page.
The cold boot attack dumps physical memory. This tactic corrupts virtual memory to frustrate analysis. The executable code is still stored in RAM somewhere, just not somewhere where you can get to it by reading from a virtual memory address. The cold boot attack would still work fine.
Finally, TRESOR and Loop-Amnesia are not broken. TRESOR-HUNT only works if you enable DMA on your FireWire bus. You shouldn't be doing that anyway.
I assume you mean PCI Express, since PCI-X is an obsolete standard not used on modern systems, but the answer is the same for PCI, PCI-X, and PCI Express, so no matter.
The TRESOR-HUNT attack works by having the attacker plug a malicious peripheral into the running computer, then having that peripheral use DMA to write malicious code into the computer's RAM which copies the encryption key out of the CPU.
Plugging a PCI card into a computer while it is running is likely to fry the motherboard, or at the very l
For all practical purposes, you are incorrect. Desktops and laptops do not typically support PCI Express hot swapping; this is a feature implemented only on high-end server chipsets.
Heh... you're lucky. I seated a PCI card in wrong once and it shorted out. Fortunately, it was only $10 or so to replace.
But, you may have a point: it might be possible to electrically tap the PCI or PCI Express bus and do bad things with DMA, even if the bus wasn't built to support hot-swapping. You'd probably need custom hardware, a lot of time, and a lot of luck, though. Also, you'd need to keep power to the CPU on, meaning stuff like chassis intrusion detectors would be a sufficient countermeasure.
Yesterday I was a dog. Today I'm a dog. Tomorrow I'll probably still
be a dog. Sigh! There's so little hope for advancement.
-- Snoopy
Bring it on, folks! (Score:5, Insightful)
The crackers are going to love breaking this in 1, 2, 3 ...
Re: (Score:2)
Re:Bring it on, folks! (Score:4, Interesting)
I am the author of Loop-Amnesia, a system similar to TRESOR, but more sophisticated in that it supports multiple encrypted volumes. After looking over the article, it does not appear that this is at all similar. It also does not appear to protect against the cold boot attack as claimed.
The authors claim a 2% performance reduction. Such a reduction implies that the instructions are not being decrypted literally on-the-fly; the reduction would be much more severe then. They're using a tactic called a "TLB split", which corrupts the cached page table so that reading memory gets you different results from executing it. A page of executable code is likely decrypted with a key stored in the CPU, put in a different physical page, and then the TLB split is performed so that executes go to the other page while reads still go to the encrypted page.
The cold boot attack dumps physical memory. This tactic corrupts virtual memory to frustrate analysis. The executable code is still stored in RAM somewhere, just not somewhere where you can get to it by reading from a virtual memory address. The cold boot attack would still work fine.
Finally, TRESOR and Loop-Amnesia are not broken. TRESOR-HUNT only works if you enable DMA on your FireWire bus. You shouldn't be doing that anyway.
Re: (Score:3)
I assume you mean PCI Express, since PCI-X is an obsolete standard not used on modern systems, but the answer is the same for PCI, PCI-X, and PCI Express, so no matter.
The TRESOR-HUNT attack works by having the attacker plug a malicious peripheral into the running computer, then having that peripheral use DMA to write malicious code into the computer's RAM which copies the encryption key out of the CPU.
Plugging a PCI card into a computer while it is running is likely to fry the motherboard, or at the very l
Re: (Score:3)
For all practical purposes, you are incorrect. Desktops and laptops do not typically support PCI Express hot swapping; this is a feature implemented only on high-end server chipsets.
Additionally, grow up.
Re: (Score:2)
Heh ... you're lucky. I seated a PCI card in wrong once and it shorted out. Fortunately, it was only $10 or so to replace.
But, you may have a point: it might be possible to electrically tap the PCI or PCI Express bus and do bad things with DMA, even if the bus wasn't built to support hot-swapping. You'd probably need custom hardware, a lot of time, and a lot of luck, though. Also, you'd need to keep power to the CPU on, meaning stuff like chassis intrusion detectors would be a sufficient countermeasure.