Explained: Patching The Installd

What am I patching?
You are patching the Installd daemon that’s in all iDevices under /usr/libexec/. It is an official Apple program.

What does Installd do?
For an illustrated explanation, read Explained: App Syncing.

It handles app installation. Any app that comes to it to be installed undergoes an authentication test. Non-official (cracked) apps are rejected and THAT is why you get xxx.IPA Is Not A Valid Ipa File. The AppStore app, Install0us, and iTunes are the three applications that send .ipa files to Installd for installation.

It also handles syncing of apps between iTunes and iDevice. When syncing from iDevice to iTunes, the apps will go to Installd for the auth test (and for compression into .ipa files) before being sent to the iTunes library. Non-official apps are deleted and THAT is why your apps get deleted after you sync. When syncing from iTunes to iDevice, iTunes sends the ipas to Installd to be installed on your iDevice. You will need AppSync to do this regardless if you use Install0us or Installous. Read How To Sync (iDevice to iTunes).

What does patching it do?
You have to patch the program so that it “forgets” to run the authentication test prior to installation/syncing.

Installous 2.0.X didn’t need patching.
Unlike Install0us which sends the .ipa file to Installd, 2.0.X uses a workaround installation method by uncon that does not involve Installd and hence the apps are not checked for authentication.

Why change the installation method?
Uncon’s installation script has a lot of dependencies, which results in a high potential for bugs, incompatibilities and installation errors. Install0us 2.5 uses the native Apple installation method, which is faster, cleaner, and works for everybody as long as you follow a simple instruction and patch your Installd properly.

Ok, I’m convinced. How do I patch?
You can use Installd Patch by adding iphone.org.hk/apt/ to your Cydia sources, OR AppSync by adding cydia.hackulo.us. To add sources, launch Cydia, go to Manage -> Sources -> Edit -> Add, and then type in the URL and tap “add”. Use ONE of them. Do not patch twice. You only have one Installd program in your iDevice.
Warning: 3GS users, you have to make do with AppSync as Installd Patch isn’t compatible for 3GS yet.

What’s the difference between Installd Patch and AppSync?
Installd Patch modifies the Installd program (legal). AppSync replaces the Installd program with a copyrighted program (illegal). Both get the same job done. Warning: If you already have AppSync, stick with it. AppSync may not restore your original Installd when you uninstall it, so when you install Installd Patch after that it runs into problems when it’s unable to find the Installd. Read the last paragraph of this article.

I get errors when patching. If you’d previously used AppSync before trying to install Installd Patch, you should have an installd.backup file in /usr/libexec/. Make a copy of that and rename it to awesomesauce. Launch Cydia and uninstall (remove) any AppSync and Installd Patch that you might have. Go back to /usr/libexec/ and delete installd and installd.backup if you still have them, and rename awesomesauce to installd. You have then restored your original installd file. Go back to Cydia again and install Installd Patch if that’s what you want.