[bradleyland]

Or you could use something like bcrypt with a configurable 'cost' and stop making up things that you think will secure your passwords.

Anything you can brute force with your hardware can be brute forced on someone else's hardware.

[praptak]

"Anything you can brute force with your hardware can be brute forced on someone else's hardware."

How doesn't this argument apply to increasing work factor in bcrypt?

[bradleyland]

Let me back up here and try to be less smarmy and more straight with the facts of the matter.

The primary reason I think your idea isn't favorable to using bcrypt is because of the weight of experience and research. Dropping bits from your salt might be a perfectly valid crypto protection technique, but when it comes to crypto, I'm inclined to go with research over cleverness.

If dropped bits from the salt were a viable means of securing passwords, I'd imagine that someone would have implemented something like this already. It's one of those "oh, that's clever" ideas, but the cleverness trap is a dangerous thing. Just because something is clever doesn't make it good.

This is one of the most oft repeated warnings when it comes to crypto: don't build your own, you'll do it wrong.

[bradleyland]

The difference is that bcrypt's cost factor is an intentional implementation with well understood results. Truncating part of your key and intentionally brute forcing it is a kludge.