The following message have been verified on Bitcoin Core and Electrum. It doesn't work on coinig(.com) because it's not on one line only.
If someone could quote this whole post it would be great.
I confirm that i (Seccour) is the owner of the following BTC addresses:
1GUejXvG7XgNzfxfcovpKwK5yc9wwENqVp
16BoqBEQLiHWonkVNvtmJsTBMGLq3PZbTn
18vYhGCPDenYmti3mzcqp6BFbvMRF8XUmL
If you need to be sure that you really deal with me, ask for a message sign by at least 2 of theses addresses.
This address alone: 1DPF6SBTWUZKqy3giUF2QrFp5TFfjtat6H should not be use to prove my identity anymore.
Message sign the 29/04/2017
Hash of the last know block: 0000000000000000015f64a972c68b0453933edd4d39f918a5a108fd0d21dc31
-----BEGIN SIGNATURE-----
1DPF6SBTWUZKqy3giUF2QrFp5TFfjtat6H
IEFzac2etsNC5PfYlIF60FbXMlRxY4FI0JuTeO7o+Q5UPEBUO9AnQFO2YaM1sWhISo+cc9i+FHXWCNLwQXOafW0=
-----END BITCOIN SIGNED MESSAGE-----
Verified with Bitcoin Core.