You have articulated my original question perfectly. I was having a difficult time explaining it. Interesting that so many people have posted ideas regarding b

You have articulated my original question perfectly. I was having a difficult time explaining it. Interesting that so many people have posted ideas regarding block chains and hashing, which is to be expected from a programmer's forum I suppose. My eventual solution all be it not perfect is to record my message on a clear night with the ISS passing over. I believe this could be faked but would be quite difficult to align my geo position, the moon phase and relative position of planets, stars and space station all inside a moving video. Thank you for your response.