If someone can open your computer and take out the RAM and walk away then you are already bogged down by much more serious security issues and there’s little to protect from keeping your encryption keys secure I expect.
Also I recall an issue that was discovered where they could spy the keys in a multi user system by looking at the cache of the CPU, and they they created fixes for that, so to use this method you’d have to un-fix that fix I guess? And then you’d have the old issue back and you re-created a security issue, so this would not be suitable for multi-user systems.

But isn’t the memristor or whatever they’ve dubbed it supposed to do away with ram degrading when the electricity is no longer applied? It’s thought that this would replace traditional ram as a way to save your computer from power outages or allowing you to turn it off and back on without reboots of the operating system.

Seems to me that we need a fundamental redesign of both the hardware and software for crypto in order to safeguard against key stealing. I thought of crypto chips, but then, who’s to say you can’t probe one of those for the data it contains?

It seems to keep coming back to physical access owning the system regardless of measures. Doesn’t the real question then become how many people you really need to stop, not how many can you stop?

I guess the real question I’m asking is why should I be worried about this? I really don’t see myself or my company as a target for this sort of thing given our size. Some day perhaps, but hopefully smarter people than I will have solved this by then.

Why not just make trivial changes to RAM so that external logic allows clearing on shutdown or on power loss? Most PCs have a permanent standby power which the clearing logic can use right after the shutdown was initiated. One could even use super caps to keep the clearing circuits alive long enough on power loss.

> Yes, but how does that prevent the case when you pull the plug?

super caps = super capacitors that store a fair bit of electrical charge. These can be used to momentarily power circuits once the power is lost. In this case, it could power a circuit that clears RAM.

why not simply make the processor on it’s last throwes just before power dies to zero ram.

there are at least 40 clock cycles from power loss until the cpu and ram lose power. More than enough to wipe the ram cells.

@wwhat: afaik the encryption of a TPM is just one part. Another major function is authentication. For trusted applications for example (in combination with processor security features). But I wonder if that prevents using memory attack to inject own non-trusted code. But probably you can’t just easily halt the CPU without noticing. And you could perhaps copy the whole state to a non-trusted platform. Oh well.

Its not so much clearing the keys from RAM, this is easy to implement as Truecrypt has shown, it clears it on suspend and shutdown. But what if I lock my computer and walk away, well then someone doesn’t need to “cold” boot it, they could just use a windows skelleton key or some other firewire fu to steal my keys out of memory.
Cold boot at present is really useful on Vista bitlockered pc’s where the key isn’t properly cleared from memory on shutdown (they rely on the misconception that ram clears on powerloss) and it isn’t even touched on suspend. Really though this attack is very limited in scope. But it does remind me of memory resident viruses back in my Amiga days that could jump disk by hiding in the memory and on soft reboot/insufficient power outage would copy themselves to a write enabled disk.
Really physical access does trump all, but I would say next version of truecrypt we see will have an option to store the keys in cache on lock pc.

Using the cache isn’t totally crazy, but I don’t think the outlined method is the right approach. If one bank were set to a cache-as-RAM mode and the MTRRs are programmed correctly, you could have a small address space treated as RAM, but not on any of the memory modules.
I don’t know if this can be set up at run time though. I have only seen it done at the CPU’s reset vector.

How about modifying a home safe and using it as a tower? That should at least keep the attacker away from the ram long enough, unless they are brave enough to drill(or however else you break into a safe) into the safe while its plugged in. Maybe use water-cooling… weekend paranoid project here I come

I am using SATA encryption hardware for my HD´s and they are safe from cold boot attack.

Recommend it!

Right now not many use cold boot attack and that includes law enforcement(FBI).

I know about a case in US where cold boot attack can be used or from what I have learned could be used but the FBI haven´t used it yet.

http://goo.gl/JkPft