I found a really interesting form tag today: <keygen>. This generates a key for me when I submit a form, so I guess I was wondering two things:

1. Does it have any practical use?
2. even if not, how would you use it? the page says the private key is stored in the local key database, but what does that mean?

Another, in related news I would guess, are there PHP functions which implement RSA or DER? I'll admit, I've never heard of DER until today.

The keygen tag works in Firefox, but not in IE.