Search for users with PGP keys

[shoutingboy]

Title
Search for users with PGP keys
Short, concise description of the idea
On the "directory search" page, add an option to "return just users with PGP/GPG public keys"
Full description of the idea
Just add a single checkbox to the directory search page, labeled "return only users with public keys" or somesuch. This would filter the results returned.
An ordered list of benefits

Users could easily find out which of their friends have PGP keys, and download the keys, by doing a directory search for friends of theirs who have keys uploaded. As it stands, the only way to do this is to go to each friend's profile page and look for the key icon.

An ordered list of problems/issues involved

It adds another line to the directory search page.

It potentially could add overhead to the directory search function, since there would be one more thing to check for.

An organized list, or a few short paragraphs detailing suggestions for implementation

At minimum, this could just mean doing a normal directory search, but only returning users who have PGP keys listed. That would require just putting a single check-box on the "search" page, asking whether to restrict results to just users with PGP keys. (Alternatively, it could be a three-way toggle--return users with keys, users without keys, or all users. But I don't know if anyone would ever want to search for just users *without* PGP IDs.)

As an advanced feature, it'd be nice to be able to search *for the keys themselves*--that is, to have the search page return all ASCII-armored keys, instead of returning the users who have keys. But that would require a lot more code!