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1024-bit RSA keys In Danger Of Compromise?
antiher0 writes "According to an email from Lucky Green that came across bugtraq yesterday, 1024-bit encryption should no longer be considered pristine. Bernstein released a proposal that outlines the creation of a machine capable of breaking 1024-bit crypto on the order of minutes or even seconds for the measly cost of ~$1B USD. For a more thorough discussion, check out the original email."
Update: 03/26 03:16 GMT by T : And don't forget to revisit Bruce Schneier's analysis of Bernstein's claims, which cast doubt on the practicality of breaking such large keys anytime soon.
If you can come up with a brute force approach to common encryption schemes, could you not stay one step ahead of something like this by utilizing multiple layers of encryption, with differing methods of encryption at each level?
Give that a brute force attack is orders of magnitude more computationally intensive than the original encryption, would this allow you to stay ahead of the curve?
Also, although the papers seem to indicate that the proposed system could try multiple forms of attacks on the encrypted data, would modifying or customizing the encryption algorithm at each layer of encryption help? Computers are great at brute force attacks, but I highly doubt a system such as this proposed one can do much in the way of analysis or reverse engineering of the encryption algorithms used...at some point, you'd have to resort to good old (and slow) human deduction...
Don't any of you bozos pay attention to prior articles? Security is about risk management. If you have something to protect that is worth $1bn for someone to steal and the only protection you have on it is 1024-bit crypto, you deserve to have it stolen.
Your homework for today is to (re)read Secrets and Lies. There will be a quiz.
The person who builds this machine may still underbid you. The machine doesn't just crack your secrets -- it's reusable. When you amortize the gigabuck over all the different people who need to be spied on, it may yet work out to be less than your minimum bribe.
As copyright owner of this comment, I authorize everyone to defeat any technological measure which limits access to it.
First, it's not that the gov't is cracking encryption of bank systems so they can steal money. The cost of cracking encrypted messages from terrorists, countries they don't like, etc. using this technology would be less than the cost of other intel methods, i.e. getting someone on the inside, not to mention the intangible cost of a human life if an agent were compromised.
Second, if you'd read the e-mail on Security Focus, the estimated price range is several hundred million dollars to about 1 billion dollars, lower if they have access to a chip fab. It also mentions that the NSA and several other countries' intelligence agencies have their own fabs. So it's not as prohibitively expensive as it sounds. The e-mail's author goes as far as saying The NSA would have to be derelict of duty to not already have built such a decryption device.
Even Bernstein's original paper is clear to point out that while his mathematical results are correct, and that his proposal does allow RSA keys of size n bits to be factored in the time we currently think it takes to crack keys of size n/~3.009, he proved this to be true *only in the asymptotic case*!!
This means that for very, very large n Bernstein's results are known to hold. His paper is actually a grant proposal requesting funding so that he can spend the next few years finding out if it's possible to apply the same techniques to practical-sized keys. As I understand it, what Bernstein wants to study will still be purely theoretical. He wants to calculate what the savings factor is for smaller keys. The reduction factor for smaller keys may be as large as 3, or it may be smaller but still worthwhile, or it may be negligible.
Even after Bernstein has done his calculations for smaller keys (which will take years) the results will still be purely theoretical, and there will likely remain a great number of practical challenges in building the rather unique kind of hardware Bernstein is proposing. It's possible that even if the theory holds for smaller keys, building a real machine may still be impractical.
For more detailed discussion than you're likely to be able to digest, go read sci.crypt.
From what I've read, I would say that if you have secrets you need to keep for more than 5 years, you might consider using a 2048-bit RSA key, or switching from RSA to ECC.
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