Also can anything be inferred by the length of the signal message? Do they pad they out or will all of the sudden sending a 2kb vs 3kb message give you away that something is different?
Personally if my life is on the line, I'd stick with the shoelaces.
> Suspected ringleader Mohamed Atta was seen repeatedly by witnesses using his Hotmail account at public libraries in Florida to surf the Internet, downloading what appeared to be pictures of children and scenes of the Middle East.[1]
> Many of the hijackers were frequent visitors to libraries and internet cafes in Florida, where they are believed to have received their final orders in coded message.[2]
Pre-9/11:
> Through weeks of interviews with U.S. law-enforcement officials and experts, USA TODAY has learned new details of how extremists hide maps and photographs of terrorist targets — and post instructions for terrorist activities — on sports chat rooms, pornographic bulletin boards and other popular Web sites.[3]
[1] https://web.archive.org/web/20011005232014/https://abcnews.g...
[2] https://www.theregister.com/2001/10/11/iomart_cashes_in_on_w... ([1] and [2] found via https://www.giac.org/paper/gsec/3494/steganography-age-terro...)
[3] https://web.archive.org/web/20030606200613/http://www.usatod... (found via https://core.ac.uk/download/pdf/11308369.pdf)