The REAL reason you cannot downgrade

Tech198

macrumors G5
Original poster
Mar 21, 2011
13,976
1,643
Australia, Perth
Apple's goal for some time was to always expiring signatures on iOS versions to lrevent diwngrades. This could be why Apple doesn't care about 3rd party sites offering diwnloads of all versions across all models of devices, even though they are point to Apple servers to download the .ipa bundle., without a valid suganture, you ll get an error in iTunes when you try to restore.

Knowing this, why was the remark to "prevent downgrading" was "....we remove something in iOS to prevent this" when in fact its not true?

The restore diesn't happen on the device, it happens via iTunes, and since all Apple is make the sigantures invalid, that's all there needs to be do e to prevent downgrading.

Or was a fake??
 

petrucci666

macrumors 6502a
Apr 30, 2009
705
4
Los Angeles, CA
I'm having a really tough time understanding anything you just said. I understand English might not be your first language, and that's ok, but I still couldn't figure out what the 'REAL reason' was. Can you explain?
 

Scott90

macrumors 6502
Jul 14, 2008
273
0
Has anyone really been far even as decided to use even go want to do look more like?
 

Tech198

macrumors G5
Original poster
Mar 21, 2011
13,976
1,643
Australia, Perth
Ok i didn't explain it clearly.


When Apple first told customers they couldn't downgrade, they origionally said "because we removed something from iOS to prevent people downgrading"

Has anyone clarrified this?? .. Basically what i mean is since the restore is done via iTunes, why would App,e need to remove anything from the phone to prevent this? Since a restore is done via iTunes on a PC or Mac and not directly from the device.
 

AppleDApp

macrumors 68020
Jun 21, 2011
2,409
42
It`s probably just code in the software that says once you have iOS X you cannot go back to iOS X -1.
 

T5BRICK

macrumors G3
Aug 3, 2006
8,086
2,055
Oregon
When you use iTunes to install iOS onto a device, it verifies that the version of iOS you're installing is still being "signed" by Apple. If it isn't being "signed" anymore, it throws an error. This function is built into iTunes and part of the iOS install process. I don't believe there is a way around it.

This has been the case for several years now. For a time, you could capture your SHSH blobs and restore older versions of iOS, but this stopped working after the iPhone 4.

The real reason you can't downgrade is because Apple doesn't let you.
 

Tyler23

macrumors 603
Dec 2, 2010
5,641
146
Atlanta, GA
Ok i didn't explain it clearly.


When Apple first told customers they couldn't downgrade, they origionally said "because we removed something from iOS to prevent people downgrading"

Has anyone clarrified this?? .. Basically what i mean is since the restore is done via iTunes, why would App,e need to remove anything from the phone to prevent this? Since a restore is done via iTunes on a PC or Mac and not directly from the device.
When you attempt to restore to a particular firmware version, the restore process must be verified through Apple's servers (this is why you can't restore without being connected to internet). When this check happens, it verifies which device you have, as well as the firmware version you are attempting to restore. They stop signing a version of iOS within days of a newer version being released. When they stop signing the previous version, it will no longer pass the verification check with its servers, meaning you will not be able to restore to that version any longer.
 

3bs

macrumors 603
May 20, 2011
5,424
19
Dublin, Ireland
It`s probably just code in the software that says once you have iOS X you cannot go back to iOS X -1.
No that's not how it works. Apple just stops signing older versions of software which must happen for you to run it on a device.

Edit: Tyler23 goes into more detail in the post above mine.
 

Nanasaki

macrumors 6502
Oct 26, 2010
319
0
Why would Apple wants to stop singing older version? I get the reason Apple wants to check signature of particular firmware. That is to prevent bad ipsw file screwing your iOS device. But with legit firmware, there is no reason to not sign it...
 

3bs

macrumors 603
May 20, 2011
5,424
19
Dublin, Ireland
Why would Apple wants to stop singing older version? I get the reason Apple wants to check signature of particular firmware. That is to prevent bad ipsw file screwing your iOS device. But with legit firmware, there is no reason to not sign it...
There are probably many reasons. Security updates. Easier to develop apps for one version of the OS then for all versions.

This is Apple. They rarely give us choices so this isn't surprising.
 

Menge

macrumors 6502a
Dec 22, 2008
609
2
Amsterdam
Parts of the device, like the modem firmware, can't be downgraded because their chips won't allow it. It's hardwired not to.

On top of that, iTunes is set to only apply firmwares that are signed by Apple and Apple will routinely expire older versions' signature.

Sometimes you can downgrade (if both versions are still being signed or you kept a cache of your firmware's signature), but your phone's modem will remain in the most up-to-date version. I haven't heard of cases where this caused problems, but I wouldn't be surprised if it did cause problems.

But the biggest reason I see is: the way you move is forward. :p
 

paulrbeers

macrumors 68040
Dec 17, 2009
3,960
120
What if your upgrade to say iOS 7 includes firmware updates to the hardware on your phone to make it capable of handling some new wiz-bang feature included in the new OS. Now if you downgrade to 6, then your hardware doesn't "look" the same to the new OS because of the new firmware. How is 6 going to handle this? Apple would have to update 6, to deal with the new updates to the hardware (which would require regression testing everything). Rather than do this, they take the easier and more fool proof plan and just not allow you to downgrade. Would it be nice to downgrade? Sure. Then again I got used to iOS 7 and now prefer it. People tend to @#$!@ and moan about change and then over time they learn to "deal" with it and then ultimately learn to accept (and maybe even prefer!) the change.
 

C DM

macrumors Sandy Bridge
Oct 17, 2011
47,538
16,040
There are probably many reasons. Security updates. Easier to develop apps for one version of the OS then for all versions.

This is Apple. They rarely give us choices so this isn't surprising.
Ultimately they don't do it because it's that much simpler not to allow it (and has the added benefit of generally getting more people onto the latest version).
 
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Nanasaki

macrumors 6502
Oct 26, 2010
319
0
What if your upgrade to say iOS 7 includes firmware updates to the hardware on your phone to make it capable of handling some new wiz-bang feature included in the new OS. Now if you downgrade to 6, then your hardware doesn't "look" the same to the new OS because of the new firmware. How is 6 going to handle this? Apple would have to update 6, to deal with the new updates to the hardware (which would require regression testing everything). Rather than do this, they take the easier and more fool proof plan and just not allow you to downgrade. Would it be nice to downgrade? Sure. Then again I got used to iOS 7 and now prefer it. People tend to @#$!@ and moan about change and then over time they learn to "deal" with it and then ultimately learn to accept (and maybe even prefer!) the change.
That is not true... There was 3 day downgrading windows since iOS 7 public release...And people downgraded had no problem with iOS 6.
 

Nanasaki

macrumors 6502
Oct 26, 2010
319
0
LOL brute force? hahaha smh

You weren't forced to upgrade.
No...not directly.... Forced download and wasting 3GB of space is way to indirectly forcing upgrade...

----------

I doubt iOS 7 could have got good adoption without these brute force upgrade tactics.
You might want change your phrase a little bit.... If downgrade is allowed, the adoption rate will not as high.
 

C DM

macrumors Sandy Bridge
Oct 17, 2011
47,538
16,040
LOL brute force? hahaha smh

You weren't forced to upgrade.
Well, almost everything was already done for you short of (even accidentally) tapping the actual upgrade button that even just appeared up for you at times.
 

Syndicate0017

macrumors 6502
May 3, 2013
405
0
LOL brute force? hahaha smh

You weren't forced to upgrade.
Well, probably 95% weren't "forced" to upgrade. When Apple is no longer signing a firmware version and a user is forced to restore (as a factory reset either does not fix the problem or they are stuck in recovery mode or something), then they are "forced" to the new version.
 

Armen

macrumors 604
Apr 30, 2013
7,375
2,207
Los Angeles
I love how people don't read the EULA when they install iOS.

By Clicking "I AGREE" you acknowledge that Apple provides you the software and can make any changes they like and you have to accept those changes.

No part of this process is "Forced".
 

C DM

macrumors Sandy Bridge
Oct 17, 2011
47,538
16,040
I love how people don't read the EULA when they install iOS.

By Clicking "I AGREE" you acknowledge that Apple provides you the software and can make any changes they like and you have to accept those changes.

No part of this process is "Forced".
Somehow "you have to accept" seems to be the opposite of "No part of this process is 'Forced'". ;)

I guess you can say that perhaps people agree to be forced...not sure if that makes it all that much better really.
 

3bs

macrumors 603
May 20, 2011
5,424
19
Dublin, Ireland
Somehow "you have to accept" seems to be the opposite of "No part of this process is 'Forced'". ;)

I guess you can say that perhaps people agree to be forced...not sure if that makes it all that much better really.
You make too much sense C DM, what are you doing on MR? :p