Confirmed: The iPad Doesn’t Need Code Signature On Apps!

Hey guys, today has been very interesting. Like most great discoveries, they happen on accident. We have tested (extensively) and have confirmed that the iPad does not require apps to be code signed!

Brandon and I have been hard at work on some projects here internally at LEI Mobile and during this, we uncovered a rather interesting piece of knowledge. The iPad doesn’t require apps to be code signed in order to run them!

Now, we ruled out “Spirit” as a cause for this, and we ruled pretty much everything else out. No other device does this.

To have a definitive answer, Brandon made a very simple, yet crucial, application for the iPhone OS. It was a simple application that we dubbed “n0S1gn”.

This would be the ultimate test to see if our discovery can be presented as fact.

We simply wrote this simple app, and didn’t sign it. It’s a completely unsigned binary. We didn’t code sign with either Apple’s Developer (official) method, or with LDID (Cydia/Jailbreak app pseudo-signature).

Now, all apps require some kind of code signature to run on the iPhone and iPod touch. This has been the case since iPhone OS 1.1.3. Even Cydia apps need some sort of signature. We use LDID to code sign our Cydia apps and we use Apple’s method to code sign our App Store apps.

So, we took an iPad (Spirit Jailbreak) on 3.2, an iPhone 3G (Pwnage Tool) 3.1.3, an iPhone 3G S (redsn0w) 3.1.3, an iPhone 3G S (Spirit Jailbroken), and an iPod touch 2G (Spirit) and then restored and redsn0w and we uploaded “n0S1gn” to all of those devices, unsigned, and guess what we found? It failed to work on all devices…except… the iPad.

We have determined that the iPad does not require apps to be code signed, at least when they are installed in /Applications.

This may change the community a lot. We may discover some interesting exploits with this discovery 🙂

More to come…

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  1. says

    NICE!!! good news for me!

    this works also for native iPad apps? I’m working on convert one of my iPhone apps into a “Universal Application” that runs in the two environments and I was worry about the code signing for native iPad apps, do you know if LDID command will work for a native iPad App?

    nice post!


  2. says

    Lol, we use a universal binary for our LEI Mobile app in iTunes.

    Also, yes it does. There are some universal binaries on Cydia that use LDID. I am considering allowing LEI Mobile for iPad/iPhone to be on Cydia as well.

    Thanks! Were gonna see if it’s the iPad or if it’s A4 now that the iPhone 4 will have an A4 processor in it.

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