In a brute force attack, every possible key is tested. If the message was encrypted with 56-bit encryption, then there are 2 to the 56th power possible keys. That s a very large number of possibilities, and 20 years ago when 56-bit encryption was first contemplated no existing computer could have tried all those keys in a human lifetime. If the encrypted material is valuable enough, it s worth a code cracker s investment to break it. That's the case with RSA, for instance.
Computers continue to get faster all the time.
This is a fact of life. Some time soon computers will be fast enough to perform brute force attacks on keys that are incrementally longer than the ones they can crack now. A brute force attack on VME keys is out of the question. No computer on earth could try all the possibilities involved, in many, many years. Based on the huge key sizes, VME is not vulnerable to an effective brute-force attack.