If you have an method for requiring n out of m key parts to use the key, it is fairly easy to see how this can be used to require n out of m characters from a password. The only problem is that just a few characters doesn't have a large enough entropy to prevent the whole thing being brute forced very quickly.

> If you have an method for requiring n out of m key parts to use the key, it is fairly easy to see how this can be used to require n out of m characters from a password.

It doesn't sound very easy to me at all. Can you explain in more detail?