Sending Coded Messages with Postage Stamps
The history of coded messages in postage-stamp placement. I wonder how prevalent this actually was. My guess is that it was more a clever idea than an actual signaling system. And I notice that a lot of the code systems don’t have a placement that indicates “no message; this is just a stamp.”
Baz • January 4, 2012 9:03 AM
Sortof related, it occurred to me last night that you can use “XEP-0301: In-Band Real Time Text” similarly. XEP-0301 is an XMPP extension that includes typing delays, to give the illusion of real-time chat while sending a max of 1 message per second. (see eg http://www.marky.com/realjabber/)
The availability of this extra channel of numbers obviously lets you send covert messages, though I wonder how you’d do it practically (so that you don’t have obvious delays from trying to keep 2 conversations going at once) – eg have 2 people at each end, one pair having the real conversation while the other is the cover? Replay an old conversation as the cover for the real one? Or simply use it to send a one-way message, like this stamp code.