The point of RSA authentication is you can give everyone your public key, and they can authenticate you without knowing your secret. Then, in case of something similar to the Gawker breach, the attacker has only the username and public key of the user, but not the private key, so they can't use it to get into any other site.

Strong passphrases is also not enough, unless the passwords are unique across sites. Some HN users may use unique passwords, but normals don't. I don't do it with 100% regularity.

What you're suggesting is that a user give a site their public key, receive some site-supplied data encrypted with their key, and be forced to decrypt it to log into the site? I guess that sounds fine, but it's no more or less secure than using a unique password, and again, now you need to carry your private key around everywhere that you want to log into anything, unless you plan on memorizing that sucker.

I suspect the real result of such a scheme is that everyone's private keys to everything would be sitting around unencrypted on USB drives and written on pieces of paper, so it would be even easier to steal their identities.

I think the solution is still -- use a password manager, and then it's easy to keep track of unique passwords across sites.

> If you only give someone a public key, > how can they authenticate you based > on that? You must be giving them some > piece of private data, or else anyone > could authenticate as you.

That's not quite the way it works. There is no shared secret required. With my public key you can create an authentication challenge that allows you to validate my identity without ever seeing my private key (or, for that matter, you can send me a message that only I can read).

Yeah, I figured out what he was getting at a moment after posting, so I edited my post with my core objection, which is just that there's really no benefit I can see to doing that instead of using memorizable passwords.