[Atrix 4G Android Development] krkeegan:
We seem to have a lot of confusion in the Atrix forum about the implications of an encrypted and or locked bootloader.

What is a bootloader?

See this article for a decent description.

Is the bootloader on the Atrix encrypted?

We don't know and likely will not know until the phone is released and people smarter than I can look at it. No reviews, including the Engadget review, have looked at whether the bootloader is encrypted. However, some have inaccurately said that it is because the installation of non-market apps is not permitted the bootloader is encrypted. However, this is a separate issue and is a requirement imposed by ATT that has nothing to do with the bootloader.

Why do people assume the bootloader is encypted?

Motorola has a strong recent history of releasing encrypted bootloaders, see the Droid X and Milestone phones. Most of the current discussion about the bootloader is limited to what we have seen from Motorola in the past. That being said, there is some hope that the bootloader will not be encrypted. In prior phones, such as the Droid X and Milestone, Motorola relied on the eFuse feature of Texas Instruments OMAP processors. Given that the Atrix uses an Nvidia Tegra 2 chip it is unlikely that Motorola can utilize the same eFuse technology.

As a result, there is some reason to be optimistic that the Atrix will only have a locked and not encrypted bootloader.

What is the difference between a locked and encrypted bootloader?

This is a good post on the topic. Locked bootloaders are on almost all android phones, including the Nexus S. Although certain locks, such as the Nexus S, are easier to open. A locked bootloader is essentially software that is written in such a way so as to prevent you from gaining access. So far XDA devs have been very skilled at cracking locked bootloaders by finding holes in this software.

An encrypted bootloader, from my understanding, is not itself encrypted, but signed by an encryption key. The phones hardware will refuse to boot unless the software that it attempts to boot is signed with the correct encryption key. The only options to crack this protection appear to be to go around the bootloader which is unlikely or to crack the encryption which also appears unlikely. See this post for more discussion.

What does an encypted bootloader mean to me?

This post at Android Forums provides a great summary of the effects of an encrypted bootloader. If you have the time, the entire thread is very informative.

The bad news is an encrypted bootloader likely means no custom kernels. This means that custom ROMs must rely on the official kernel. It also means the OS version (Froyo, Gingerbread . . .) is limited to whatever the official release is. The good news is that root access is still be possible. Root access allows you to run certain applications as the root or administrator. This allows for a lot of customization and hacking of your phone.

In the end, an encrypted bootloader may hinder your ability to completely hack the phone.

Can an encrypted bootloader be cracked?

Unlikely. For a brief discussion see this post and read the thread for a better understanding. I am aware that there is a team working on cracking the Milestone encryption using the BIONIC platform and a distributed computing effort, see androinc.net. However, even that team admits that the second coming of the dinosaurs may occur before they crack the encryption. I believe on the Milestone that the encryption is 1024 bit, which according to androinc.net may take hundreds of thousands of years to crack using a brute force method, even on a distributed computing platform.

Can a locked bootloader be cracked?

We won't know until we see it, but likely yes. Generally all software coded by humans has some error in it that can be exploited.

Why should I care if the bootloader protection cannot be circumvented?

You don't have to. But, in today's environment, consumers are tied to a 2 year contracts but new phones are released on a 1 year or less timeline. This means the device you buy today will likely be forgotten by your carrier and the phone manufacturer long before your contract is up. The inability to load custom kernels means that consumers cannot upgrade their own phones after the manufacturer decides to no longer support the phone. The decision to stop supporting upgrades often occurs well before a phones 2 year birthday, see the Motorola Upgrade Roadmap.

In addition, many people believe that they have purchased the phone hardware and should be permitted to do anything that they please with the hardware.

** I do not claim to be an expert, I have only recanted the results of my research. If I have made a mistake please let me know.