Now let’s re-explain rainbow tables:
1. take a “dictionary” —- say, of all combinations of alphanumerics
less than 15 characters
2. hash all of them
3. burn the results onto a DVD.
You now have several hundred billion hash values that you
can reverse back to text —- a “rainbow table”.
Alphanumeric usually means either 36 or 62 possible characters. Let's take 36. Then there are 36^14 possible 14 character alphanumeric passwords. (He said less than 15, so we should also consider 13 characters, 12 characters, and so on, so this is going to come out a little low since I'm just doing 14 exactly). That's 6.14 x 10^21 possible passwords.If you could compute 10 billion hashes/second, that would take 20000 years. (41 million years if mixed case alphanumeric is allowed). Could anyone REALLY make a table covering all 14 character or less alphanumerics in 2007, and fit it on DVD?
I believe there were tables for 14 character Windows passwords then, but due to poor design Windows passwords were in effect treated as two 7 character passwords. You just needed tables that covered the hashes of all 7 character passwords, which is a lot more tractable. Could that be what the author was thinking of?