[tdjsnelling]

That is something glaringly obvious that I should have considered, thanks for pointing it out. I'll make the change to require a specific message.

[a1369209993]

Probably glaringly obvious (but in this case also), but you should make sure that the specific message starts with something highly conspicuous like "DAT KEYSERVER KEY REVOCATION REQUEST ID#<token>" to avoid social engineering someone with "Hey can you sign this token so I know you're you?".