Even if you’re not heavily vested in the “hacking” and device unlocking scene, you’ve probably heard the term “jailbreak” used in conjunction with Apple’s line of devices. The term has become so ubiquitous that other device hacking groups have begun to use the term instead of “hacking” because of the softer connotation. After all, not all hacking has malicious or illegal intent. Think of jailbreaking as “making a device do something it was not originally intended for by removing manufacturer limitations.” Jailbreaking does not inherently violate the Digital Millennium Copyright Act (DMCA), but there are other issues involved that we will cover later in this series.

The Overview

Apple devices – sometimes referred to as “iDevices” – include the iPad, iPod Touch and other iPods, iPhone, etc. along with the Apple TV. These devices all operate on basically two levels. The outermost level is generally referred to as the firmware. In mobile devices, firmware is the equivalent of the operating system on your computer, like Microsoft Windows or Mac OS X. However, in a mobile device – this OS is actually stored in flashable (programmable) memory within the device rather than on the storage medium (such as a hard drive). On iDevices, this firmware is often referred to as “iOS.” The most current version of the iOS is 4.2. as of the time of this writing.

The innermost level is sort of like your computer’s BIOS. These are the built-in functions of the iPod that allow it to be programmed and updated when Apple releases new features for your device. The most notable update was the change from the old iOS 3.x to the newer iOS 4, which brought features like multitasking and better performance for most devices.

The Nitty-Gritty

Most Jailbreak programs make the entire process pretty simple. We’ll go into what programs are available and which is best for your particular iDevice and firmware revision in a later post. What’s interesting is what goes on behind the scenes in the entire process (Well, if you’re a geek like me and want to know how things work).

First, the jailbreak program will generally send a command to your iDevice while it’s plugged up to your computer. The command tells the iPod to reboot and enter “Recovery Mode.” If your iDevice had suddenly crashed a horrible, horrible electronic death and would not start (even though it was charged) – Apple Care Support would probably have you start your device in this mode and let iTunes re-flash the firmware to it. This is usually a last resort method (as it wipes your media completely off the device). In this case, jailbreaking acts more like a software “upgrade,” and maintains your media usually without a clean wipe.

Once your iDevice is in this mode, it’s become willing to accept changes to its programming by applying a firmware package. These are usually files that iTunes downloads from Apple to get updates for your iDevice. Most jailbreaking programs will modify iBoot on your device to accept customized firmware packages (commonly referred to as IPSW files, since that’s the extension the file uses).

When iBoot has been successfully modified, the jailbreak program will either automatically patch your existing IPSW firmware file or have you download a fresh one that it will modify and apply to your device. If all goes successfully, the iDevice will reboot and have a new app installed, usually one called Cydia or Rock (two of the most popular). From there, the sky’s the limit! Your device is now considered “jailbroken” and can install apps from either the Cydia or Rock app stores. A lot of the apps are free, but some are still for purchase. After all, the point of jailbreaking is to get your iDevice to download and install unofficial apps, not just get them for free.

Why Jailbreak?

There are plenty of interesting applications out there that add functionality to your iDevice that Apple either didn’t approve of or the author decided not to submit their app to the App Store. For example, people are using apps to unlock their iPhones to use on a different carrier (GSM networks only, for now, CDMA are not supported in hardware), or turn their iPhone into a wireless access point. Jailbreaking opens up your device to a monumentally larger selection of apps.

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