To prove that you own a Bitcoin address, send a signed message together with the address. Anyone can then use MultiBit to verify that the message was signed with the address's private key. From the Tools select "Sign message"
The "Clear All" button will erase the contents of all fields.
If you select "Copy All" a Bitcoin signed message will be copied to your clipboard. You can then paste this into an email or chat window to transfer the signed message to a recipient. Below is an example.
-----BEGIN BITCOIN SIGNED MESSAGE----- Hello World -----BEGIN BITCOIN SIGNATURE----- Version: MultiBit HD (0.1) Comment: https://multibit.org Address: 16R2kAxaUNM4xj6ykKbxEugpJdYyJzTP13 H0b22gIQIfutUzm7Z9qchdfhUtaO52alhNPK3emrkGOfbOzGHVPuWD9rMIphxniwBNgF/YN4c5C/dMwXz3yJz5k= -----END BITCOIN SIGNATURE-----