Darel Rex Finley in 888

iOS Jailbreaking — A Perhaps-Biased Assessment

2015.02.24   prev     next

WHY do some people jailbreak their iOS devices, and why does Apple try to prevent them from doing so? Are the jailbreakers winning this fight, or is Apple? This article attempts to answer these questions.

First, a caveat: I am not an expert on jailbreaking. Also, I’m one of the most raging Apple fans you’ll ever meet. So is it really possible that this article could offer a reasoned view of this topic? Well, maybe. In the early ’80s, I killed a lot of time cracking copy-protection schemes on the Apple II, so I’ve been on the other side of this fence, and I know a fair amount about how computers (and protection schemes) work at a low level. Also, the subject of jailbreaking is highly politicized, and so you may not find anyone willing to give you the straight dope about it. For example, in the purportedly encyclopedic, reference site Wikipedia, the article on iOS jailbreaking currently has no more than this to say about why Apple would want to stop the practice:

Apple checks apps for compliance with its iOS Developer Program License Agreement before accepting them for distribution in the App Store. However, their reasons for banning apps are not limited to safety and security and may be regarded as arbitrary and capricious.

The entry (currently) does not mention piracy: not as a reason why Apple might want to block jailbreaking, nor as a reason why anyone would want to jailbreak their device. No mention of piracy at all, in the entire article!

So, to get a clear picture of this subject, you may have no choice to but rely on multiple sources — some pro-jailbreaking, and others con. Consider this the con position — but hopefully informative nonetheless.

Before iOS

In the quarter-century prior to the iPod, home computing systems came in roughly two categories: wild-west, anything-goes, tinkerer computers, and locked-down game consoles.

The game consoles ran only cartridges developed by pre-approved development companies. Piracy, while not necessarily impossible for serious commercial pirates who manufacture counterfeit merchandise, was completely impossible for casual users — i.e. the typical home user couldn’t conceivably copy game cartridges for their friends and family members. (They could, however, sell, trade, or give away cartridges they had grown bored with.)

The wild-west computers (i.e. all home/personal computing platforms prior to iOS) allowed rampant copying/running of any program at all. Software authors/publishers tried valiantly to create their own copy-protection schemes, but in vain, because all it took was one dedicated cracker to strip the copy-protection off of an app, and then any casual user could copy that app to blank media, unhindered. Even without the internet, pirated apps and games spread like wildfire from person-to-person. (Also, without the internet, it was pretty hard for people to purchase those apps legitimately; most of them couldn’t be found at the local computer store.)

In terms of encouraging a high quality and quantity of app development, each of these two systems had its own advantages and disadvantages: Game consoles were immune to casual piracy (and low-quality junk, and malware), but were only for games, and allowed little or no access to skilled indie development. Personal computers tapped into a huge base of developers, but left those developers vulnerable to casual piracy, and left the user vulnerable to malware and scams.

A widely touted truism is that casual piracy doesn’t really hurt software developers, because if the typical casual pirate has a thousand pirated apps, but could only conceivably have been expected to purchase ten of those apps if he hadn’t been able to pirate them, then 99% of that piracy didn’t really hurt anybody. The problem is that if the user doesn’t buy those ten apps, and those ten combined with those of other casual pirates’, make up 90% or more of potential purchases, then developer income may be only a small fraction of what it would be if that piracy had been impossible. Yes, you can’t count all the pirated copies as lost sales, but the great majority of sales may be lost nonetheless.


With its i-devices — starting with the iPod in 2001, which could play songs but not copy them to other iPods nor to personal computers, and leading to ultimate fruition with the App Store in early July of 2008 — Apple created a bold experiment: What would happen if we could combine the advantages of both systems in one? What if we could have an app platform that’s effectively locked-down against casual piracy (and even against the loaning, trading, and giving-away of used apps), against buggy, very-low-quality crap, and against scams and malware — but still keep the system highly accessible to the broad base of indie developers? What happens then?

Well, now we know! What happens is an explosion of quality app development, the like of which has never been seen on this earth. And while it’s true that the great majority of iOS app developers make little-or-no money (don’t I know), that’s simply due to intense competition. The high number of successful developers, and the degree of their success, is unprecedented.


Jailbreakers are persons who believe that iOS should be like all the personal computing platforms that came before it: anything goes; I can do whatever I please. As signified by the name they have chosen for their activity, “jailbreaking” (Apple refers to it simply as “hacking”), they think of Apple’s control of iOS as a “jail,” and so to figure out a way to disable Apple’s controls, and seize ultimate control of the device is equivalent to “breaking” out of Apple’s “jail.”

Jailbreakers never cite the desire for casual piracy as a reason to jailbreak their device. If it actually was, would they say so openly, given that piracy is illegal, and given that a public campaign to pressure Apple into giving up on a locked-down system will win more support if the public doesn’t think the crusade’s point is piracy?

We can’t read their minds, but we can learn a lot from their choice of terminology. If I said that physical locks on physical doors, and security cameras in stores, are a “jail” that should be forcibly “broken” — not so that I, or anyone else, can do illegal things, but just to facilitate good uses of such ultimate freedom — would anyone believe me? And even if they thought I was sincere, would they follow my advice? And if they did, what would be the result?

If all that these jailbreak people really want is the freedom to tinker with the inner workings of their own phones, then why don’t they just buy Android phones? Even if Android ultimately doesn’t win the market battle for the great majority of apps (or even users) — so what? Android phones will still exist if even a few percent of phone owners prefer them. If these people really consider iOS a jail, then it’s a jail they can easily walk right out of: to Android, or to some other mobile OS. Why the desire to prevent such a controlled ecosystem as Apple’s from existing at all — other than to facilitate mass, casual piracy? Because mass, casual piracy can be effectively facilitated only on the system for which the great bulk of quality apps are written. That would be iOS.

It’s super obvious why Apple wants to block jailbreaking. They’ve got the best thing going in app ecosystems, ever, and they don’t want it to be ruined. Duh.

So who’s winning the war?

Code Signing

Apple blocks jailbreaking with code signing, which uses the private/public key signing system. Here’s a quick description of how you use that (general) system:

  • Make up a private key that you share with no one.

  • Run the private key through an algorithm that generates its corresponding public key. You may share this public key with the public (if you want), and no one will be able to extract your private key from it.

  • To digitally “sign” any document, you can run that document and your private key through an algorithm that generates a signature. You can append this signature to the bottom of your document to prove that you signed it.

  • Anyone can verify your signature by running the signed document and your public key through an algorithm that reliably determines if the document was signed using your private key. (But the private key is never exposed.)

iOS uses code signing (to the best of my understanding) like this:

  1. When an iOS device is powered-up, it automatically runs a startup program in the ROM.

  2. The ROM program loads the first piece of the OS from mass storage (the flash memory chips) into main memory (RAM). The program expects this piece of code to be signed, and verifies the signature using a public key that is also contained in the ROM. (Only Apple has the private key.) If the signature looks good, the ROM program runs the program contained in that first piece.

  3. The first piece loads more pieces of the OS into RAM, and verifies those pieces’ signatures against the same public key in the ROM.

  4. This process continues until the entire OS is loaded and running.

  5. The OS expects all apps to be similarly signed by Apple, and won’t install and/or run them if they’re not.

If this scheme is working correctly, the only way to jailbreak an iOS device would be by physically cracking it open and replacing the ROM chips with custom ROM chips that permit the device to launch a non-Apple-signed, pirate version of iOS. Although a jailbreaker might indeed be able to do that, what they want to do is to create an internet-distributable program that will allow anyone to jailbreak their iOS device, with no physical modification required. That should be impossible — so how is it that any significant number of iOS devices are jailbroken at all?

Because of flaws. Like all hackers, jailbreakers simply look for unforeseen mistakes in Apple’s implementation of the above-described security system, vulnerabilities by which a hacker might inject malicious code into the device and get the processor running that code in a privileged mode where it can take over the system. An Operating System is an enormous beast, and eliminating all such flaws can be very hard, especially when new features are being added to the OS regularly.

Tethered vs. Untethered

There are two kinds of jailbreaks: “tethered” and “untethered.” The difference is that with an “untethered” jailbreak, you can restart the device without having to tether it to your computer and effectively re-jailbreak it. Naturally, jailbreakers prefer the untethered jailbreak.

While any jailbreak relies on finding a flaw in the OS that allows takeover of the system, an untethered jailbreak must also find a flaw in the startup process, so that when the device starts up, it can be tricked by the code in the flash memory into entering a jailbroken state. Finding such flaws in the startup process is much harder, and fixing those flaws is much easier, because the startup process is a much simpler thing than the full OS. For this reason, I have high confidence that Apple will always be able to cause sufficient trouble to the creators of untethered jailbreaks to prevent them from providing reliable, timely, untethered jailbreaks to the general public.

I have far less confidence that Apple can cause much trouble for tethered jailbreaking, because the entire OS would have be flawlessly secured to accomplish that. But it doesn’t matter, because if most members of the iOS-using public wouldn’t even consider a tethered jailbreak, then all Apple has to do to keep winning this war is to cause a lot of difficulty for the creators of untethered jailbreaks. Which they seem to be doing.

When the iPhone 5 was released, it took jailbreakers four months to figure out how to jailbreak it; then Apple promptly patched it so the jailbreak wouldn’t work. The latest version of iOS (8.1.3) has been out for the better part of a month with no jailbreak in sight. The only people who will put up with these kinds of delays and unreliability are people who have a dedicated hatred of the new world Apple is creating, a philosophical mental block against the idea that wild-west computing shouldn’t go on forever.


It’s hard to find anything like a consensus about what percentage of iOS users jailbreak their devices. But here’s a clue: When Apple released iOS 7, the user adoption rate reached 60% in about a week, whereas the first jailbreak wasn’t available for over three months. This strongly suggests that most people are plenty happy with the system Apple has created, and aren’t consumed with the craving to subvert it.

In about a decade, we will have seen a quarter-century of the locked-down iDevice — equalling the quarter-century of personal computing that preceded it. Does anyone really doubt that we will look back and say that a revolution was in the making? If you invest for the long term, consider this fair warning.


Update 2015.09.21 — Five days after iOS 9’s release, Cybersecurity startup Zerodium openly offering $3 million for discovery of untethered jailbreaks.


Update 2017.11.27 — Lead jailbreaking pioneers now say that iOS jailbreaking is effectively over.


See also:
iOS Jailbreaking — A Perhaps-Biased Assessment
A Secure Backdoor Is Feasible
Method of Implementing A Secure Backdoor In Mobile Devices


prev     next



Hear, hear

prev     next

Best Recent Articles

Method of Implementing A Secure Backdoor In Mobile Devices

When Starting A Game of Chicken With Apple, Expect To Lose

How I Clip My Cat’s Nails

Seasons By Temperature, Not Solstice

It’s Not A Criticism, It’s A Fact

Features (Regularly Updated)

A Memory of Gateway — news chronology of Apple’s ascendancy to the top of the technology mountain.

iPhone Party-Poopers Redux and Silly iPad Spoilsports — amusing litanies of industry pundits desperately hoping iPhone and iPad will go away and die.

Embittered Anti-Apple Belligerents — general anger at Apple’s gi-normous success.


My books

Now available on the iBookstore!



Daring Fireball

The Loop



Red Meat

Despair, Inc.

Real Solution #9 (Mambo Mania Mix) over stock nuke tests. (OK, somebody made them rip out the music — try this instead.)

Ernie & Bert In Casino

Great Explanation of Star Wars

Best commercials (IMO) from Superbowl 41, 43, 45, 46, and 47

Kirk & Spock get Closer

American football explained.

TV: Better Call Saul; Homeland; Survivor; The Jinx; Breaking Bad; Inside Amy Schumer

God’s kitchen

Celebrity Death Beeper — news you can use.

Making things for the web.

My vote for best commercial ever. (But this one’s a close second, and I love this one too.)

Recent commercials I admire: KFC, Audi

Best reggae song I’ve discovered in quite a while: Virgin Islands Nice

Pinball Arcade: Unbelievably accurate simulation of classic pinball machines from the late ’70s through the ’90s, with new ones added periodically. Like MAME for pinball — maybe better.

d120 dice: You too (like me) can be the ultimate dice nerd.

WiFi problems? I didn’t know just how bad my WiFi was until I got eero.

Favorite local pad thai: Pho Asian Noodle on Lane Ave. Yes, that place; blame Taco Bell for the amenities. Use the lime, chopsticks, and sriracha. Yummm.

Um, could there something wrong with me if I like this? Or this?

This entire site as a zip file — last updated 2018.02.01

Previous articles

Nothing More Angry Than A Cornered Anti-Apple

Let ’Em Glow

The Ultimate, Simple, Fair Tax

Compassion and Vision

When Starting A Game of Chicken With Apple, Expect To Lose

The Caveat

Superb Owl


Basic Reproduction Number

iBook Price-Fixing Lawsuit Redux — Apple Won

Delusion Made By Google

Religion Is A Wall

It’s Not A Criticism, It’s A Fact

Michigan Wolverines 2014 Football Season In Review

Sprinkler Shopping

Why There’s No MagSafe On the New Mac­Book

Sundar Pichai Says Devices Will Fade Away

The Question Every Ap­ple Naysayer Must An­swer

Apple’s Move To TSMC Is Fine For Apple, Bad For Samsung

Method of Implementing A Secure Backdoor In Mobile Devices

How I Clip My Cat’s Nails

Die Trying

Merger Hindsight

Human Life Decades

Fire and the Wheel — Not Good Examples of A Broken Patent System

Nobody Wants Public Transportation

Seasons By Temperature, Not Solstice

Ode To Coffee

Starting Over

FaceBook Messenger — Why I Don’t Use It

Happy Birthday, Anton Leeuwenhoek

Standard Deviation De­fined

Not Hypocrisy

Simple Guide To Pro­gress Bar Correctness

A Secure Backdoor Is Feasible

Don’t Blink

Predictive Value

Answering the Toughest Question About Disruption Theory

SSD TRIM Command In A Nutshell

The Enderle Grope

Aha! A New Way To Screw Apple

Champagne, By Any Other Maker

iOS Jailbreaking — A Perhaps-Biased Assessment

Embittered Anti-Apple Belligerents

Before 2001, After 2001

What A Difference Six Years Doesn’t Make

Stupefying New Year’s Stupidity

The Innovator’s Victory

The Cult of Free

Fitness — The Ultimate Transparency

Millions of Strange Dev­o­tees and Fanatics

Remember the iPod Killers?

Theory As Simulation

Four Analysts

What Was Christensen Thinking?

The Grass Is Always Greener — Viewing An­gle

Is Using Your Own Pat­ent Still Allowed?

The Upside-Down Tech Future

Motive of the Anti-Ap­ple Pundit

Cheating Like A Human

Disremembering Mi­cro­soft

Security-Through-Obscurity Redux — The Best of Both Worlds

iPhone 2013 Score Card

Dominant and Recessive Traits, Demystified

Yes, You Do Have To Be the Best

The United States of Texas

Vertical Disintegration

He’s No Jobs — Fire Him

A Players

McEnroe, Not Borg, Had Class

Conflict Fades Away

Four-Color Theorem A­nal­y­sis — Rules To Limit the Problem

The Unusual Mo­nop­o­list

Reasonable Projection

Five Times What They Paid For It

Bypassable Security Certificates Are Useless

I’d Give My Right Arm To Go To Mars

Free Advice About Apple’s iOS App Store Guidelines

Inciting Violence

One Platform

Understanding IDC’s Tablet Market Share Graph

I Vote Socialist Be­cause...

That Person

Product Naming — Google Is the Other Microsoft

Antecessor Hypotheticum

Apple Paves the Way For Apple

Why — A Poem

App Anger — the Supersized-Mastodon-In-the-Room That Marco Arment Doesn’t See

Apple’s Graphic Failure

Why Microsoft Copies Apple (and Google)

Coders Code, Bosses Boss

Droidfood For Thought

Investment Is Not A Sure Thing

Exercise is Two Thirds of Everything

Dan “Real Enderle” Ly­ons


Ignoring the iPod touch

Manual Intervention Should Never Make A Computer Faster

Predictions ’13


Zeroth — Why the Century Number Is One More Than the Year Number

Longer Than It Seems

Partners: Believe In Ap­ple

Gun Control: Best Ar­gu­ments

John C. Dvorak — Translation To English

Destructive Youth

Wiens’s Whine

Free Will — The Grand Equivocation

What Windows-vs.-Mac Actually Proved

A Tale of Two Logos

Microsoft’s Three Paths

Amazon Won’t Be A Big Winner In the DOJ’s Price-Fixing Suit

Infinite Sets, Infinite Authority

Strategy Analytics and Long Term Ac­count­a­bil­i­ty

The Third Stage of Computing

Why 1 Isn’t Prime, 2 Is Prime, and 2 Is the Only Even Prime

Readability BS

Lie Detection and Psy­chos



Microsoft’s Dim Pros­pects

Humanity — Just Barely

Hanke-Henry Calendar Won’t Be Adopted

Collatz Conjecture A­nal­y­sis (But No Proof; Sorry)

Rock-Solid iOS App Stability

Microsoft’s Uncreative Character

Microsoft’s Alternate Reality Bubble

Microsoft’s Three Ruts

Society’s Fascination With Mass Murder

PlaysForSure and Wikipedia — Revisionism At Its Finest


Patent Reform?

How Many Licks

Microsoft’s Incredible Run

Voting Socialist

Darwin Saves

The Size of Things In the Universe

The Self-Fulfilling Prophecy That Wasn’t


Nobody Was In Love With Windows

Apples To Apples — How Anti-Apple Pundits Shoot Themselves In the Foot

No Holds Barred

Betting Against Hu­man­i­ty

Apple’s Premium Features Are Free

Why So Many Computer Guys Hate Apple

3D TV With No Glasses and No Parallax/Focus Issues

Waves With Particle-Like Properties

Gridlock Is Just Fine

Sex Is A Fantasy

Major Player

Why the iPad Wannabes Will Definitely Flop

Predators and Parasites

Prison Is For Lotto Losers

The False Dichotomy

Wait and See — Windows-vs-Mac Will Repeat Itself

Dishonesty For the Greater Good

Barr Part 2

Enough Information

Zune Is For Apple Haters

Good Open, Bad Open

Beach Bodies — Who’s Really Shallow?

Upgrade? Maybe Not

Eliminating the Im­pos­si­ble

Selfish Desires

Farewell, Pirate Cachet

The Two Risk-Takers

Number of Companies — the Idiocy That Never Dies

Holding On To the Solution

Apple Religion

Long-Term Planning

What You Have To Give Up

The End of Elitism

Good and Evil


How Religion Distorts Science

Laziness and Creativity

Sideloading and the Supersized-Mastodon-In-the-Room That Snell Doesn’t See

Long-Term Self-De­lu­sion

App Store Success Won’t Translate To Books, Movies, and Shows

Silly iPad Spoilsports

I Disagree

Five Rational Coun­ter­ar­gu­ments

Majority Report

Simply Unjust

Zooman Science

Reaganomics — Like A Diet — Works

Free R&D?

Apple’s On the Right Track

Mountains of Evidence

What We Do

Hope Conquers All

Humans Are Special — Just Not That Special

Life = Survival of the Fittest

Excuse Me, We’re Going To Build On Your Property

No Trademark iWorries


Twisted Excuses

The Fall of Google

Real Painters

The Meaning of Kicking Ass

How To Really Stop Casual Movie Disc Ripping

The Solitary Path of the High-Talent Pro­gram­mer

Fixing, Not Preaching

Why Blackmail Is Still Illegal

Designers Cannot Do Anything Imaginable

Wise Dr. Drew

Rats In A Too-Small Cage

Coming To Reason

Everything Isn’t Moving To the Web

Pragmatics, Not Rights

Grey Zone

Methodologically Dogmatic

The Purpose of Lan­guage

The Punishment Defines the Crime

Two Many Cooks


One Last Splurge

Making Money

What Heaven and Hell Are Really About

America — The Last Suburb


What the Cloud Isn’t For

Diminishing Returns

What You’re Seeing

What My Life Needs To Be

Taking An Early Re­tire­ment

Office Buildings

A, B, C, D, Pointless Relativity

Stephen Meyer and Michael Medved — Where Is ID Going?

If You Didn’t Vote — Complain Away

iPhone Party-Poopers Redux

What Free Will Is Really About

Spectacularly Well

Pointless Wrappers

PTED — The P Is Silent

Out of Sync

Stupid Stickers

Security Through Nor­mal­cy

The Case For Corporate Bonuses

Movie Copyrights Are Forever

Permitted By Whom?

Quantum Cognition and Other Hogwash

The Problem With Message Theory

Bell’s Boring Inequality and the Insanity of the Gaps

Paying the Rent At the 6 Park Avenue A­part­ments

Primary + Reviewer — An Alternative IT Plan For Corporations

Yes Yes Yes


Hey Hey Whine Whine

Microsoft About Microsoft Visual Microsoft Studio Microsoft

Hidden Purple Tiger

Forest Fair Mall and the Second Lamborghini

Intelligent Design — The Straight Dope

Maxwell’s Demon — Three Real-World Ex­am­ples


Entitlement BS



Einstein’s Error — The Confusion of Laws With Their Effects

The Museum Is the Art

Polly Sooth the Air Rage

The Truth

The Darkness

Morality = STDs?

Fulfilling the Moral Du­ty To Disdain



Real Design

The Two Rules of Great Programming


The End of the Nerds

Poverty — Humanity’s Damage Control

Berners-Lee’s Rating System = Google

The Secret Anti-MP3 Trick In “Independent Women” and “You Sang To Me”

ID and the Large Had­ron Collider Scare

Not A Bluff

The Fall of Microsoft

Life Sucks When You’re Not Winning


The Old-Fashioned Way

The Old People Who Pop Into Existence

Theodicy — A Big Stack of Papers

The Designed, Cause-and-Effect Brain


IC Counterarguments

The Capitalist’s Imaginary Line

Education Isn’t Eve­ry­thing

I Don’t Know

Funny iPhone Party-Poopers

Avoiding Conflict At All Costs

Behavior and Free Will, Unconfused

“Reduced To” Ab­sur­dum

Suzie and Bubba Redneck — the Carriers of Intelligence

Everything You Need To Know About Haldane’s Dilemma

Darwin + Hitler = Ba­lo­ney


Designed For Combat

Speed Racer R Us

Bold — Uh-huh

Conscious of Con­scious­ness

Future Perfect

Where Real and Yahoo Went Wrong

The Purpose of Surface

Eradicating Religion Won’t Eradicate War

Documentation Overkill

A Tale of Two Movies

The Changing Face of Sam Adams

Dinesh D’Souza On ID

Why Quintic (and Higher) Polynomials Have No Algebraic Solution

Translation of Paul Graham’s Footnote To Plain English

What Happened To Moore’s Law?

Goldston On ID

The End of Martial Law

The Two Faces of Ev­o­lu­tion

A Fine Rec­om­men­da­tion

Free Will and Population Statistics

Dennett/D’Souza Debate — D’Souza

Dennett/D’Souza Debate — Dennett

The Non-Euclidean Ge­om­e­try That Wasn’t There

Defective Attitude Towards Suburbia

The Twin Deficit Phan­toms

Sleep Sync and Vertical Hold

More FUD In Your Eye

The Myth of Rub­ber­neck­ing

Keeping Intelligent Design Honest

Failure of the Amiga — Not Just Mis­man­age­ment

Maxwell’s Silver Hammer = Be My Honey Do?

End Unsecured Debt

The Digits of Pi Cannot Be Sequentially Generated By A Computer Program

Faster Is Better

Goals Can’t Be Avoided

Propped-Up Products

Ignoring ID Won’t Work

The Crabs and the Bucket

Communism As A Side Effect of the Transition To Capitalism

Google and Wikipedia, Revisited

National Geographic’s Obesity BS


Theodicy Is For Losers

Seattle Redux


Living Well

A Memory of Gateway

Is Apple’s Font Rendering Really Non-Pixel-Aware?

Humans Are Complexity, Not Choice

A Subtle Shift

Moralism — The Emperor’s New Success

Code Is Our Friend

The Edge of Religion

The Dark Side of Pixel-Aware Font Rendering

The Futility of DVD En­cryp­tion

ID Isn’t About Size or Speed

Blood-Curdling Screams

ID Venn Diagram

Rich and Good-Looking? Why Libertarianism Goes Nowhere

FUV — Fear, Uncertainty, and Vista

Malware Isn’t About Total Control

Howard = Second Com­ing?

Doomsday? Or Just Another Sunday

The Real Function of Wikipedia In A Google World

Objective-C Philosophy

Clarity From Cisco

2007 Macworld Keynote Prediction

FUZ — Fear, Uncertainty, and Zune

No Fear — The Most Important Thing About Intelligent Design

How About A Rational Theodicy

Napster and the Subscription Model

Intelligent Design — Introduction

The One Feature I Want To See In Apple’s Safari.