A ways back (might have even been a couple years), I came up with an idea for something called Anonymous Private Mail, or a-p mail, a system of e-mail which provides for much greater privacy. Rather than using an e-mail address, a-p mail identifies individuals by their public/private key pair used to encrypt the e-mails (the private part). What made the a-p mail system so novel was that it was able to route a message from sender to receiver without ever knowing the keys of the sender or recipient (the anonymous part). Because of this, the e-mail server (or anyone monitoring it) could not even tell if two e-mails were sent by the same person or received by the same person (in contrast to normal e-mail systems, where the server always knows at least the e-mail address of the receiver).
I was initially concerned about disclosing how it works, especially with regard to patenting it. This system originated in one of my stories (the universe of Starfall and Eve of Tomorrow, which I briefly mentioned previously) as a method allowing criminals (especially terrorists) to communicate. I was concerned that if I patented it, it would be used in the same was it was used in the story. For this reason I posted the basic description (essentially what I wrote above) on this blog and some forums, asking for comments about whether I should patent it or keep it secret forever.
Eventually, a consensus opinion was reached that if I'd managed to come up with this idea, others would also be able to, so the only thing that keeping it secret would do is prevent me from potentially receiving licensing fees for the patent on it. So, after a great deal of procrastination (me being me), I finally wrote up the patent application and submitted it to the US Patent and Trademark Office last Thursday.
While not entirely unforeseeable, I was still very surprised to find two men in suits at my front door on Friday. To make a long discussion short, they explained that they were from the US Department of Homeland Security; they had seen my patent application, and, apparently, I wasn't the only one concerned about the possible application of the method to criminal organizations (particularly terrorism). They informed me that they'd deleted my patent application, and presented me with a federal gag order barring me from disclosing the details of the method to anyone else (including making further attempts to patent it).
So, I guess I won't be patenting it afterall. Funny how all decisions become easy when you're reduced to only a single option... At least this won't impact my stories - as they weren't targeted specifically at people with great knowledge of computers, most people wouldn't have understood the thing even if I had explained how it worked in the stories.