Has anyone heard about an encryption cluster where one can increase the length of encryption keys by adding processing machines to the network? No matter how long the encryption keys are, sooner or later, considering the increase in CPU power, the encryption keys will be broken. How would one go about building such a scalable key-encryption cluster using linux?
I assume you mean a decrypting cluster, right? A single machine is plenty powerful enough to encrypt. You might enjoy reading http://www.ijde.org/docs/02_fall_art4.pdf Anyway I don't have the answer to you question, but with a 128-bit key, your sooner or later is a long way away. We do some computer forensics and may have to break some keys in the future so I pay a little attention to the problem. There is a program that runs on a 100 machine cluster that will break a 40-bit key in a few days. Using the same program / computers to break a 128-bit key, it will take longer than the Sun's lifetime to break it. Speed increases of 10^9, 10^12, or even 10^15 are needed and those are not close. Maybe something like the Seti program that can steal cycles from millions of computers could conceivably help. So if machines get 1000 times faster in the next x years, and a seti like background program allows billions of computers to work in parallel, then 128-bit keys may be breakable, but then the bad-guys just move to more bits. Brute-force decrypting is definitely a losing battle.