Sunday, March 13, 2016

The “Encryption” Debate

by Steve Gibson

“Encryption” is quoted in the title of this essay because encryption is NOT what any of this is actually about. The debate is not about encryption, it’s about access. It should be called “The Device Access Debate” and encryption should have never been brought into it.

Modern smartphones have batteries, screens, memory, radios, encryption, and a bunch of other stuff. Collectively, they all make the phone go, they are all good, and we want as much of each them as the device’s manufacturer can squeeze in. We do not want smaller batteries, lower resolution screens, less memory, less capable radios, or weaker encryption. And it is entirely proper for Apple to boast about the battery life, screen resolution, memory, radio, and encryption strength of their products. The FBI is entirely correct when it says that Apple is actively marketing the newly increased encryption strength of their latest phones and operating systems. That’s as is should be, in the same way that Apple is marketing their device’s battery life and screen resolution. Those are all features of modern smartphones, and Apple knows what their users want. We all want those things.

The fourth amendment to the US Constitution states: The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

Mapping the 4th amendment onto encrypted devices:
Without weakening their devices’ encryption, Apple could arrange to be able to respond to court orders in the United States. If Apple wished to be able to respond to lawful search warrants to unlock their devices, they could embed a single, randomly derived, high-entropy (256-bit) unique per-device key in the hardware secure enclave of every device. This key would not be derived from any formula or algorithm, so there would be no master secret that might somehow escape or become known to a malicious agency. It would be truly random and far too lengthy for any possible brute force guessing attack to be feasible. Upon embedding each individual random per-device key, Apple would securely store a copy of that key in their own master key vault. In this way, without sacrificing anyone’s security, only Apple, on a device by device basis, could unlock any one of their own devices.

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1 comment:

  1. Follow-up, 20 hours later:
    I wrote this post to separate the issue of encryption strength from access policy. Much ink and angst has been expended over phrases involving “backdoors” and “weakened encryption.” All such concerns are red herrings because unbreakable encryption simply gives Apple unbreakable access control. Apple could design a completely secure facility to manage unlocking individual devices. Whether Apple should do so is deservedly one of the most critical questions of our time, and is worthy of truly engaging debate. If we decide that we want to leave things as they are, that’s fine. But we should not conflate whatever policy Apple implements with their user’s security. We can have both.