Nice idea and one which works for pure RC4, but unfortunately not for 128 bit, 88 bit known + 40 bit unknown "export" SSL.
Netscape's SSL uses "40 bit keys" that are composed in a strange way: you are given 88 bits of known key, and this is combined with the 40 bit key, to give a 128 bit key. That key is used to do the encryption. The problem is that this has a unix password salt like effect, only this time there are 88 bits of salt rather than 12 bits. So this means that you can't precompute anything on the 40 bits as the 88 bits are randomly generated, and likely vary with each session.
Ah!!! Then here's my next alternative attack. By a 100x100 Transputer (about \$120,000 to make one) and program it to crack the SSL running 10,000 parallel computations. If it takes 2 years for the whole keyspace for each computer, it takes 1.75 hours to span the whole key space. Taking a 3 year write-off time and spending $30,000 per year for maintenance, this comes to $70,000 per year, or $14.08 per cracked key. If I do 1,000 keys in parallel, that reduces the cost to 1.4 cents per key. -- -> See: Info-Sec Heaven at URL http://all.net Management Analytics - 216-686-0090 - PO Box 1480, Hudson, OH 44236