Another suggestion, I might be wrong though.
If you just put Bitcoin address or PGP key, it is easy to impose another person. A signed message is better.
False.
In reality is it the other way around.
The Bitcoin address or
public PGP key cannot be use to impose another person.
Most user have this information public available in their signature, contact information, keybase.io etc.
But you need it to published somewhere in bitcoin talk in order to be able to retrieve your account if it gets stolen.
Publishing a generic signed message is not cleaver, it can be used by an imposter.
If you sign something, the message
must include the purpose of the signed message
and include the time/date.
This is an example of a not so cleaver signed message:
Message: "This is TookDk from Bitcointalk"
Signature:
This is much better:
Message: "Date: 2015.03.19. The purpose of this message is to prove that TookDk from Bitcointalk is in control of bitcoin address 1TookDkVTaqsCn56Xo7aMfUMAUN3NhRjN at this point in time"
Signature: