Using code words in a normal-looking message is a cheap and effective way to communicate.
Several American businessmen are in Kuala Lumpur, Malaysia trying to get a contract signed for a lucrative mining deal. Mike, the head negotiator, communicates with his iPhone over a 3G GSM network, and he uses his corporate e-mail account via his laptop.
Before he left home he came up with a series of code words to use when he communicates with his boss. This simple and cheap method defeats and misleads national-level eavesdropping, hackers, competitors who eavesdrop, and everyone else who wants to spy on him. Just keep your special word list safe. Beware of thinking that old school is somehow wrong, or that it offers flimsy security. The opposite is true. Flying under the radar is a very good idea these days, and simple is good. He printed his little code word table on a piece of paper and he hid that paper inside his wallet.
Here is the code word list for the above scenario:
SPECIAL WORD(s) MEANING
NORTH THE BUSINESS DEAL DID NOT GO THROUGH
SOUTH THE BUSINESS DEAL DID GO THROUGH
EAST THINGS LOOK PROMISING BUT NOT YET COMPLETE
WEST HUGE SUCCESS
NORTHEAST UTTER FAILURE
NORTHWEST WE NEED MORE TIME
NICE PLACE WE ARE BEING WATCHED
GOOD RESTAURANT PROBABLY WE ARE NOT WATCHED
CHINESE THEY SIGNED THE CONTRACT SECRETLY WITH US
JAPANESE THEY REFUSED TO SIGN THE CONTRACT
INDIAN THEY SIGNED THE CONTRACT WITH US OPENLY
THAI THEY ARE NOT CORRUPT
WRITE YOU TOMORROW OTHERS ARE OFFERING PERKS
CALL YOU TOMORROW WE HAD TO OFFER SOME PERKS
One can then write a misleading message containing special words with special meanings. So here is the letter Mike writes:
I am very sorry to say that the deal did not go through. We are extremely disappointed by the behavior of their people. Tonight we are going to take a break after all these days of hard work. We are going to that Chinese restaurant west of here that you said is a nice place. Call you tomorrow.
Come up with traffic that sounds reasonable given the realities of the context. In the scenario above one could expect that a Chinese, Thai, Japanese, or Indian restaurant really does exist west of the speaker’s location. Tell everyone else involved in the business transaction to stay mum over the deal, and tell them to be especially careful over the phone or on the internet. Best practice would be to assure that as few people know about it as possible. Only those who need to know should be told about it.
The message and code word table above is for a specific purpose. A longer table can be the basis for extended conversations on varying subjects. Keeping the code word table secret is a priority. One can write it down, one can print it at home on a small piece of paper, or one could encrypt it with a 4096 bit PGP key and use it on a computer that is never attached to the internet. This last course of action is the least recommended.
And yes, if the situation is that bad, find a Chinese restaurant west of you and have dinner after you send your fake message.
The point of all this is that simple human means can defeat elaborate mechanical threats. It does not take high technology to defeat the masters of high technology. It simply takes a little thoughtful effort.