If you use a 128 bit, 256 bit, ect... encryption but only have a password that is, say, 20 characters long, doesn't that mean that in order to decrypt a system, an attack should be launched at a password? If this is the case, why does bit length matter?
What Brute Force tool are you using, and why is this so important? Did you just forget a file password, or are you trying to do questionably legal things?
Please provide more info. Also, I believe that in most password cracking programs, the attack is launched at the file/application itself, but I may be wrong.
Also, 20 characters long is a lot more than 20 bits. Correct me if I'm wrong, but you seem to misunderstand encryption or perhaps the binary language altogether. A 20-digit password unencrypted would be 160 bits (20 X 8 because one character is a byte, not a bit).
I don't use Brute Force tools, but I do have one. I'm not too familiar with it, though, so I don't know the exact answer to your question. Hope this helps, though.