Crypto-keys break question

["Anders Rundgren" <[e-mail]>]

Hi 
Some Internet-banks use key-pad boxes for authentication and signing.

A popular brand uses an 8-digit input string that produces an 8-digit result
and with no timing built-in.  On the manufacturer's site there is not a single word on
crypto-graphic strength which makes me wonder how great this thing really is.

Question: This should be like a 27-bit symmetric key which should be *very* easy to break assuming
that you have a few input and  output values at hand.  Is this a correct assumption?
If so, how many seconds/minutes/hours on a standard-PC?  Any links?

Anders