Signed message:
-----BEGIN BITCOIN SIGNED MESSAGE-----
1FLLVFpdnBQLULcQvYLUqKHiqvfKEjFCDx
-----BEGIN SIGNATURE-----
1FLLVFpdnBQLULcQvYLUqKHiqvfKEjFCDx
IBeWWFdIuSXseEs/kkGfLqH5IAJL7mZeNbjPIcmEKyFmFLO0QD0nBT1KAiQGdHIzgHs8PkEXKDtm8nPpaNe0VrA=
-----END BITCOIN SIGNED MESSAGE-----
Whilst not being the proper message format, it verifies and therefore is adequate. If you want to do this 100% properly, then you'd sign this message (but not required at this point):
This is investments.blockchain, and today is 12.02.2016. I'm signing this message in order to prove ownership of my address used to invest into ASC.