XPost: misc.phone.mobile.iphone   
   From: marianjones@helpfulpeople.com   
      
   WolfFan wrote:   
   > On Dec 31, 2025, badgolferman wrote   
   > (in article <10j4psg$35r54$1@dont-email.me>):   
   >   
   >> Marian wrote:   
   >>   
   >>> Because of these mechanisms, an iOS IPA is not a portable software   
   >>> artifact. It is a cryptographically-constrained container that can   
   >>> only be installed when Apple authorizes the transaction for a   
   >>> specific Apple ID on a specific device class.   
   >   
   > Intriguing. I once had a Windows phone. It was a work device, the company   
   > built a number of apps for WinPhone. Then MS changed the OS, and the old apps   
   > didn't work with the new OS. The company rewrote their apps. And MS changed   
   > the OS again, and the rewritten apps didn't work with the new OS. Again.   
   > And the company went to Android and Apple. I replaced the WinPhone with an   
   > iPhone; the company apps, rewriten for iOS, worked.   
   >   
   > Meanwhile, I got an Android phone to replace my old persopnal Motorola   
   > flip-phone. This device was a disaster. It froze, it crashed, it dropped   
   > calls, it never got calls... I replaced it with an iPhone. And, to simplify   
   > things, I used Apple's stuff to copy the contents, including the company   
   > apps, over to the new iPhone. It worked. I have replaced both phones multiple   
   > times since. All apps move over. Not ONE has EVER been device-locked to an   
   > old phone. Not one. All apps worked on BOTH phones.   
   >   
   > And I got an iPad. Again, to simplify life, I used Apple's stuff to copy   
   > everything over to the iPad. Almost all apps had no problems; a few (none of   
   > them Apple apps except for the original Weather app; note that a later   
   > Weather app now works on iPads and was automatically installed during an   
   > update) were iPhone-only and didn't copy; two (neither of them Apple apps)   
   > popped up a request to update to an iPad-compatible version, which when I   
   > said yes downloaded automatically from the Apple Store. I could have used the   
   > iPhone version, but in both cases the various controls swam in a display that   
   > they weren't designed for; these were banking apps, from Citi and Chase.   
   > The iPad versions were designed for the larger iPad screen. Two apps, MS   
   > Authenticator and the Google equivalent, both transfered over but could   
   > required fiddling to get full functions out of them; this was expected, they   
   > _are_ security apps, after all. I got a companyiPad; again things worked the   
   > way that my personal iPad had. I have since replaced both iPads without   
   > problems. Not only were almost all apps NOT device-locked, they almost all   
   > worked on different types of devices.   
   >   
   > I've been using iPhones for abouut 15 years and iPads for over a decade. I   
   > don't see any evidence of device-locking.   
   >>   
   >> When I used iTunes to back up my device to the computer, you had the   
   >> ability to save IPAs and reinstall older versions to your new device.   
   >> When a newer version of iTunes came out that removed that capability I   
   >> complained about it here and nospam directed me to a version of iTunes   
   >> which still did that. I still have the installation program he   
   >> recommended but haven't installed it on my Windows 11 laptop. These   
   >> days I back up my phone to iCloud. I know you don't approve of that   
   >> but I'm fine with it.   
   >   
   > I back stuff up to iCloud. And to my Mac desktop. And to my Windows desktop.   
   > I run full backups. I keep the backups on USB devices. Every so often I   
   > format one of my devices (Settings/General/Erase All Content and Settings)   
   > and do a full restore from backup, 'cause it ain't a backup if it ain't   
   > been tested; so far, no problems. Note that that's a restore from a backup   
   > on a USB device formatted ExFAT.   
      
   Hi WolfFan,   
      
   Happy New Year!   
      
   Thank you for describing your love of Apple products and how well they work   
   for you. Your experiences described above with migrating between iPhones   
   and iPads are completely valid, but they do not contradict the technical   
   point being discussed.   
      
   What you are describing is Apple's migration system, not the underlying   
   mechanics of how iOS apps are packaged, encrypted, or restored.   
      
   The distinction matters, because the question here is not whether apps   
   appear to transfer between devices, but whether an IPA is a portable   
   installer and whether it's locked to an AppleID (aka Apple Account).   
      
   Here is the part that is easy to miss:   
      
   A. iOS apps are never copied from one device to another.   
      During any restore or migration, whether iCloud, iTunes, Quick Start,   
      device to device, or the old iTunes IPA library, the app binaries   
      themselves are not transferred.   
      
      Only the app data is transferred.   
      The apps are always re-downloaded from Apple's servers.   
      
   B. Your apps always "moved over" because the new device simply contacted   
      Apple, presented your Apple ID entitlements, and Apple issued a fresh,   
      device-specific encrypted copy of each app. As long as the app is still   
      available and Apple is still signing that version, everything works   
      seamlessly.   
      
   This does not mean the apps were portable or copied from the old device.   
   It also does not mean the IPA format was ever a portable installer.   
   And it certainly doesn't mean your identity wasn't embedded into the IPA.   
      
   Here are the technical facts.   
      
   1. IPAs are encrypted with FairPlay.   
      The executable inside an IPA is encrypted and cannot run   
      on any device until Apple issues device-specific decryption keys.   
      
   2. The IPA never contains those keys.   
      This is why an IPA cannot be installed offline or moved to   
      another device that isn't registered to a given Apple ownership.   
      
   3. During restore, iOS never installs the binary from the IPA.   
      Even in the old iTunes era, the IPA served only as a receipt + blob   
      proving entitlement.   
      
   4. Apple always re-downloads the app.   
      If Apple stops signing a version, the IPA on disk becomes unusable,   
      even if you still have it.   
      
   5. Your successful migrations simply mean Apple continued to authorize   
      your apps. That is good, but it does not change how the system works.   
      
   6. The user's Apple ID entitlement is embedded into the IPA in the form   
      of a receipt. The IPA contains a small receipt file that identifies   
      the Apple ID that purchased or downloaded the app. This receipt is   
      what proves entitlement. It does not contain the decryption keys for   
      the app, but it does contain the Apple ID identity information   
      that Apple uses to decide whether to issue a new, device-specific   
      
   [continued in next message]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)