A Thermodynamics Argument for Cryptographers in the Cryptowars

Alt title: Will backdoor cryptography bring about the eventual heat death of the universe? Technically.

I've been thinking about the Cryptowars for a while, and I wanted to share an analogy I've been thinking about.

The second law of thermodynamics states that global entropy cannot decrease - informally, this means the global amount of disorder in a system can never decrease. In physics, “Maxwell’s Demon” is a thought experiment that theoretically violates the second law of thermodynamics. In this thought experiment, a demon could allow cold particles into a chamber through its gate one way, and hot particles through the other, thereby decreasing the total entropy of the system, by taking a well-mixed arrangement, and putting it into a more organized (and less likely) orientation.

Image Credits: Wikipedia

This promise of reversing entropy is critical, and could provide technological solutions to nearly every kind of problem, including the eventual heat death of the universe. Maxwell’s demon was proposed in 1867, and year after year, it is shown that Maxwell’s demon could not know which particle belongs where and direct them accordingly. Similar to good-Samaritans and criminals, it remains impossible to differentiate cold and hot particles, without expending proportional amounts of energy to investigate their identity.

Similarly, since the 1960s law enforcement has been fighting to have increased centralized power to audit and monitor its people in order to “catch the bad guys”, while cryptographers have been fighting to have increased privacy and security. These legal, technological, and moral debates have been termed the CryptoWars. We observe that without perfect knowledge of a person, it is impossible to only let the “right” people have privacy; the same way that it is impossible to let Maxwell’s Demon violate the second law of thermodynamics by selectively letting some particles through one way and others another.