Read the "Verified e-mail protocol" thingy instead. The blurb the link on HN points to is indeed completely useless. They don't verify e-mail ownership through

Read the "Verified e-mail protocol" thingy instead. The blurb the link on HN points to is indeed completely useless. They don't verify e-mail ownership through crypto means - they use the fact that e-mail is identity. Basically, your mailhost (or a proxy, like browserID) holds your public key, while your browser holds your private key. Now, when you authenticate against any BrowserID auth site, you simply sign with your private key and provide the e-mail address. Since the browser stores both, that's a trivial interaction. The site then verifies your signature with the mail host. (That's where the asymmetric crypto comes in) At least that's how I understand it - their explanation is indeed a bit cryptic. Hope they clean it up.