CODEWITHSUNDEEP
csecurityencryptioncryptographyaes
coder543
coder543

Reputation: 801

Protecting crypto keys in RAM?

is there any way to protect encryption keys that are being stored in RAM from a freezer attack? (Sticking the computer in a freezer before rebooting malicious code to access the contents of RAM)

This seems to be a legitimate issue with security in my application.

EDIT: it's also worth mentioning that I will probably be making a proof of concept OS to do this on the bare metal, so keep in mind that the fewer dependencies, the better. However, TRESOR does sound really interesting, and I might port the source code of that to my proof of concept OS if it looks manageable, but I'm open to other solutions (even ones with heavy dependencies).

Upvotes: 5

Views: 801

Answers (3)

John Deters
John Deters

Reputation: 4391

As Sergey points out, you cannot stop someone from attacking the RAM if the hardware is in their possession. The only possible solution to defend hardware is with a tamper resistant hardware security module. There are a couple of varieties on the market: TPM chips and Smart Cards come to mind. Smart cards may work better for you because the user should remove them from the device when they walk away, and you can simply erase the keys when the card is removed.

I would do a bit more risk analysis that would help you figure out how likely a frozen RAM attack is. Which computers are most at risk of being stolen? Laptops, servers, tablets, or smart phones? What value can your attackers possibly get from a stolen computer? Are you looking to keep them from decrypting an encrypted disk image? From recovering a document that's currently loaded in RAM? From recovering a key that would lead to decrypting an entire disk? From recovering credentials that would provide insider access to your network?

If the risks are really that high but you have a business need for remote access, consider keeping the secrets only on the secured corporate servers, and allowing only browser access to them. Use two factor authentication, such as a hardware access token. Perhaps you then require the remote machines to be booted only from read-only media and read-only bookmark lists to help ensure against viruses and other browser based attacks.

If you can put a monetary value on the risk, you should be able to justify the additional infrastructure needed to defend the data.

Upvotes: 0

Will
Will

Reputation: 2130

You could use something like the TRESOR Linux kernel patch to keep the key inside ring 0 (the highest privilege level) CPU debug registers only, which when combined with an Intel CPU that supports the AES-NI instruction, doesn't need to result in a performance penalty (despite the need for key recalculation) compared to a generic encryption implementation.

Upvotes: 9

Sergey L.
Sergey L.

Reputation: 22542

There is no programmatical way. You can not stop an attacker from freezing your computer and removing the RAM chips for analysis.

If someone gains access to your hardware - everything you have on it is in the hands of the attacker.

Always keep in mind: http://cdn.howtogeek.com/wp-content/uploads/2013/03/xkcd-security.png

Upvotes: 0

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