Migration of users from Slashdot

The problem

Slashdot users are a community, where users are known by nicks. Starting with a new set of nicks would disrupt the years--long network of acquaitances, etc.

Preserving nicks

A simple system could be build, which would allow for safe and authorised migration of nicks of willing users.

If anyone would want to register on Altslashdot with a nick that already exists on Slashdot, the user would be presented with a generated key. The user would then need to post any comment on Slashdot, that would contain that key. The migrating user would then present a link to that comment in the registration form.

Then, we would know, that a user with a nick we know from Slashdot is really that user, and not a copycat.