Technology

Apple's open letter on encryption

Big respect for Tim Cook and Apple for publishing this.

The government is asking Apple to hack our own users and undermine decades of security advancements that protect our customers — including tens of millions of American citizens — from sophisticated hackers and cybercriminals. The same engineers who built strong encryption into the iPhone to protect our users would, ironically, be ordered to weaken those protections and make our users less safe.

We can find no precedent for an American company being forced to expose its customers to a greater risk of attack. For years, cryptologists and national security experts have been warning against weakening encryption. Doing so would hurt only the well-meaning and law-abiding citizens who rely on companies like Apple to protect their data. Criminals and bad actors will still encrypt, using tools that are readily available to them.

This article breaks it down.

Again in plain English, the FBI wants Apple to create a special version of iOS that only works on the one iPhone they have recovered. This customized version of iOS (*ahem* FBiOS) will ignore passcode entry delays, will not erase the device after any number of incorrect attempts, and will allow the FBI to hook up an external device to facilitate guessing the passcode. The FBI will send Apple the recovered iPhone so that this customized version of iOS never physically leaves the Apple campus.

As many jailbreakers are familiar, firmware can be loaded via Device Firmware Upgrade (DFU) Mode. Once an iPhone enters DFU mode, it will accept a new firmware image over a USB cable. Before any firmware image is loaded by an iPhone, the device first checks whether the firmware has a valid signature from Apple. This signature check is why the FBI cannot load new software onto an iPhone on their own — the FBI does not have the secret keys that Apple uses to sign firmware.

An interesting note is that devices with the secure enclave would not be susceptible to this back door.

At this point it is very important to mention that the recovered iPhone is a 5C. The 5C model iPhone lacks TouchID and, therefore, lacks the single most important security feature produced by Apple: the Secure Enclave.

If the San Bernardino gunmen had used an iPhone with the Secure Enclave, then there is little to nothing that Apple or the FBI could have done to guess the passcode. However, since the iPhone 5C lacks a Secure Enclave, nearly all of the passcode protections are implemented in software by the iOS operating system and, therefore, replaceable by a firmware update.

Update: Or not. Apple says all devices at risk.

And herein lies the rub. There has been some chatter about whether these kinds of changes would even be possible with Apple’s newer devices. Those devices come equipped with Apple’s proprietary Secure Enclave, a portion of the core processing chip where private encryption keys are stored and used to secure data and to enable features like TouchID. Apple says that the things that the FBI is asking for are also possible on newer devices with the Secure Enclave. The technical solutions to the asks would be different (no specifics were provided) than they are on the iPhone 5c (and other older iPhones), but not impossible.

The point is that the FBI is asking Apple to crack its own safe, it doesn’t matter how good the locks are if you modify them to be weak after installing them. And once the precedent is set then the opportunity is there for similar requests to be made of all billion or so active iOS devices. Hence the importance of this fight for Apple.