What happens when a technocratic police state mandates that all communication within its borders must follow only an encryption scheme of which the government possesses the key?
How possible would it be for two citizens to communicate secretly through the use of stenography?
In today’s world of facial recognition cameras, microscopic communication chips, high altitude unmanned robotic drones, and other ingenious state-funded devices; questions like the ones posted above are becoming more relevant as time moves forward.
A groundbreaking study has recently appeared coming from a joint partnership between MIT, Harvard, and the University of California-Riverside. In it, authors Thibaut Horel, Sunoo Park, Silas Richelson and Vinod Vaikuntanathan explore ways in which decrypted ciphertexts can still contain hidden information.
The subversive field of stenography is integral to the premise and conclusion of the piece.
How Stenography Works
Stenography is the study and practice of hiding secret information inside open information.
For example, suppose Alice wanted to send Bob coordinates for an illicit trade deal. In addition, suppose both of them lived in a place where the government checks all mail for contraband and evidence of rebellion.
Alice cuts a slit between a postcard, slides a small piece of paper inside and then glues it back together, hiding the message inside. Someone trying to intercept the message will see only a postcard, but Bob knows better and gets the message intact.
This is stenography at its most basic.
Of course, security can be enhanced. Suppose Alice is under suspicion and her mail is more thoroughly checked apart from the norm. Alice does the same trick as above, only this time the message is coded using the very basic Caesar cipher.
All the Caesar cipher means is that every letter in the alphabet is shifted forward three spaces—X, Y and Z become A, B and C.
So now if an agent gets a hold of the message inside instead of reading “Meet at cock avenue tonight,” it will appear as “phhw dw frfn dyhqxh wrqljkw.”
This is a very easy cipher to decode, but this is just the basics. It can be modified so the alphabet is shifted whatever number of times one wants in either direction, which is pretty neat.
Totalitarian Overlords Keyed In
The paper “How To Subvert Backdoored Encryption” shows that even if powerful government entities decipher every bit of communication between citizens, secret point-to-point messaging can still exist under those entities’ noses.
This is shown through a number of theorems which provide in-depth detail as to the inner workings of cryptography. There were a couple of hurdles to get through, however.
One impossibility found was this process. The receiving party extracts hidden bits of data one ciphertext at a time by the application of a single decoding function. This would not work as a subliminal ciphered communication must be a two-party protocol. That is, the key to decrypt the message must be generated from factors possessed by the sender and receiver.
Another impossibility was that if a cover distribution was chosen adversarially, that non-trivial stenographic communication would be impossible.
In order to subvert the government produced encryption communication must appear at every time to be as innocuous as possible. A hidden message becomes easy to spot after the first when the opposition factor becomes obvious.
After a great deal of research, the scientists came up with a multi-message subversive scheme which beat the opposition. It had mostly to do with pseudo-random key exchange protocols.
The Door Cracks Open
Research such as the above and other papers of its kind will be of increasing interest the more government learns about technology.
United States federal law officials continue to push tech companies into creating backdoors into products such as smartphones and tablets.
While officials state that such security holes would only be used by warrant holders, it may be argued that a person owning a device known to contain built-in breaches in its design may have no reasonable expectation of privacy, so no warrant would be needed to conduct a search.
Designing for built-in faults seems like a bad practice to get in the habit of doing.
The Federal Bureau of Investigation has been pushing this at least since 2010. Yet, in the wake of the 2015 San Bernardino shooting in which 14 people lost their lives, the FBI called again for a push in the legislature for backdoors into iPhones.
A serious concern of all civilized countries, from the U.S. to Iran, from France to Somalia, is how to protect ourselves from terrorism.
Michael Hayden, formerly head of the Central Intelligence Agency, has been quoted saying that the U.S. is safer and more secure without backdoors when considering the question of American security and safety as a whole.
His reasoning is as follows. Such laws would be mostly futile because they would only apply to products manufactured and programmed within the jurisdiction of the U.S. borders. Very little prevents a terrorist from picking up an iPhone made in China with apps programmed in India.
So much software is open-sourced and easy to download that it’s easy to see that such laws would be ineffective in the current environment.
Chinese Netizen Cultural Subversion
China gets as close to a nightmare authoritarian surveillance state, as was outlined in the research paper “How To Subvert Backdoored Encryption,” as one can get today. Yet some Chinese internet people have taken to using slang as a form of stenography.
Grass mud horse or cǎonímǎ sounds much like cào nǐ mā, which means “fuck your mother” in one of the rich Chinese dialects. “Mother” is what the Chinese communist party enjoys being portrayed as to its people.
Numerous other slang phrases have cropped up over the past decade and are in wide online use among Chinese people who dislike censorship.
Ecks Versus Sever
Secrecy can bring a lot of enjoyment to anyone interested spooky happenings.
Modern cryptography and stenography take a large deal of math to perform well but there are some old ciphers that can be played with too.
One such code is the Vigenère cipher. It works by taking the principles of the Caesar cipher and multiplying it by whatever the keyword is.
It is built up as so: Each letter of the alphabet is listed as first along a row with every other letter coming after the first in a column. A shifts the alphabet no times, B shifts it once, C shifts it twice and so on.
And so on.
Now suppose you wanted to hide a message using this. Let’s say the message is “I snort coke with teddy bears.” All we need now is a key that will overlay the message in a repeating manner. Say the key-word is “KEY”. K=10 E=4 Y=24.
I SNORT COKE WITH TEDDY BEARS
K EYKEY KEYK EYKE YKEYK EYKEY
S WLYVR MSIO AGDL ROHBI FCKVQ
Because “K” shifts the alphabet forward ten times “I” becomes “S.”
Anyway, I’ll leave you with this phrase, see if you can get it using the Vigenère cipher. The keyword is one smaller step harder than “password” and is located somewhere on this web page. Have fun!