On Fri, Jun 10, 2011 at 1:14 AM, Paul Hoffman <[email protected]> wrote:
> Greetings again. I am helping someone design a system that will involve > giving someone > a randomly-generated key that they have to type in order to unlock data that > is private > but not terribly valuable. Thus, we want to keep the key as short as > practical to reduce > typing and mis-typing, but long enough to prevent trivial brute-force > attacks. The > encryption will be AES-128 in CBC mode. > > What is the current state of brute-force attacks on AES-128 blobs? Are there > recent > results where we can estimate the cost of brute-forcing 64-bit and 80-bit > keys? One indicator is the Copacobana machine, built from FPGAs, The first version a few years back cost 9,000 euro and broke DES in a week. There's a later version. http://www.copacobana.org/ Of course a bunch of those in parallel could break it faster. That's a 56-bit key. 64-bit is 256 times harder, but certainly within reach of an attacker with large resources. Judging solely by this, only someone with a huge budget, such as a major nation's intelligence agency, could afford to attack 80-bit keys. _______________________________________________ cryptography mailing list [email protected] http://lists.randombit.net/mailman/listinfo/cryptography
