In this article, we will discuss the question of what firmware Apple signs.

Usually after installing new system problems arise in iPhone operation and iPad. For various reasons, it is not possible to fix them, and then the question arises of rolling back to the old version of the system. In this guide, we will look at how to find out which latest version of iOS and other operating systems are still signed by Apple.

Why is this needed?

Not everyone knows, but rolling back an iPhone to a previous version is essentially impossible. Apple stops making signatures for old, outdated versions of the system some time after the release of a new one.

This is done for security reasons, as new versions fix vulnerabilities that threaten the safety of personal data. In the old assembly, vulnerabilities do not disappear anywhere.

So it turns out that for a successful rollback, you need to find out which version of iOS will be obtained in the end. Most fast way we presented next.

How to know if Apple is signing the firmware?

• Open the ipsw.me resource. It's unofficial but safe

• Select your device name

• Find your model in the list

• See what firmware is available in the section Signed IPSWs
• Here you can download the desired one and use it

This method allows you to determine the available versions of the system in a few clicks and download them. This method is especially relevant for those who are not used to following company news, but who needed a system rollback.

What iOS signs firmware?

On the this moment the situation is as follows.

The sixth and seventh generation iPhones can be rolled back to versions 9.3.5, 10.0.1, 10.0.2.

The same situation with iPhone smartphones 5, 5c, 5s and 4s.

iPhone 4 supports firmware versions - 7.1.2 - unlimited, 7.1.1, 7.1, 7.0.6, 7.0.4, 7.0.3, 7.0.2, 7.0, 6.1.3, 6.1.2, 6.1, 6.0.1 , 6.0, 5.1.1, 5.1, 5.0.1, 5.0, 4.3.5, 4.3.4, 4.3.5, 4.3.4, 4.3.3, 4.3.2, 4.3.1, 4.3, 4.2.10, 4.2 .9, 4.2.8, 4.2.7, 4.2.6, 4.2.5, 4.2.1, 4.1, 4.0.2, 4.0.1, 4.0 - only if SHSH hashes are present.

iPhone 3GS - 6.1.6, 4.1 - unlimited, 6.1.3, 6.1.2, 6.1, 6.0.1, 6.0, 5.1.1, 5.1, 5.0.1, 5.0, 4.3.5, 4.3.4, 4.3. 5, 4.3.4, 4.3.3, 4.3.2, 4.3.1, 4.3, 4.2.1, 4.0.2, 4.0.1, 4.0, 3.1.3, 3.1.2, 3.1, 3.0.1, 3.0 only with SHSH hashes.

iPhone 3G - 4.2.1, 4.1, 3.1.3, 3.1.2, 3.1, 3.0.1, 3.0, 2.2.1, 2.2, 2.1, 2.0.2, 2.0.1, 2 - unlimited, 4.0.2, 4.0.1, 4.1 - with SHSH hashes.

Hey! Any person who uses the iPhone (iPad) sooner or later simply has to face such a concept as “Signature iOS firmware". Most likely, this will happen at the moment when, for some reason, he does not like the new update and he has a great desire to “return everything as it was” (roll back to the old version of iOS).

Desire is good, but “I want” alone is clearly not enough. Indeed, in order to return the firmware, the most important condition must be met - Apple must sign this version software. What is this signature and is it possible to do without it? Now I'll tell you everything quickly - let's go!

Let's start, of course, with the basics.

What is an iOS Firmware Signature?

talking plain language- this is the "good" from Apple to install a specific version of the firmware. Didn't understand what it was about? Let's take a look in a little more detail...

The most important thing to remember:

Apple (in most cases) only allows you to install the latest version of the software. There are no intermediate options and free "jumps" from one version to another. Do you want to reinstall, restore, update operating system on your iPhone or iPad? You have only one way - installing the latest iOS.

It was for this that the “firmware signature” was introduced. How does it work?

Front iOS installation a request is always sent to the Apple servers. If Apple sees that the firmware version differs from the latest, then the installation is prohibited (iTunes "gives" error 3194).

Thus, the company is more or less in control of the situation with software on manufactured devices.

How to check if Apple signs the firmware?

It was not in vain that I made a small clarification and wrote that “Apple (In most cases) allows installation of only the latest iOS versions". Indeed, sometimes it is still possible to install the previous version of the firmware!

And when does this opportunity arise? (I highly recommend you check it out!). But if you are too lazy to read, then here are the two most common options:

1. Immediately after release new version, Apple is still signing the previous one for some time. This usually lasts for a short time - a maximum of a week.
2. The company "just has something going wrong" and starts signing much older versions of iOS. This happens very rarely and lasts a very small amount of time - a maximum of a day.

So how do you know which version of iOS is currently being signed by Apple for a particular iPhone or iPad? Everything is very simple:

Important! The information on the site is always up-to-date - Apple firmware signature verification is carried out almost every minute.

You can immediately download the file to your computer, and then install the firmware directly on the device.

Is it possible to put the firmware without a signature?

No, a signature is always required. Although, for fairly old devices, such as:

1. iPad 1.
2. iPad 2.
3. iPhone 5 and "younger".

Some workarounds do exist. But they require too many conditions to be met: a jailbreak done, a saved SHSH certificate, a certain firmware and a suitable device model.

If all these terms are familiar to you, then you can try to roll back the firmware without a signature. How to do it? I had the idea to write all these instructions here, but then I changed my mind:

• First, the article would have turned out just huge.
• Secondly, it would be useful to too few people.
• Thirdly, if a person owns an iPad 1 and purposefully saved an SHSH certificate for it, then he knows how to return the old version of iOS for his tablet “without my snotty advice”.

So there is only one thing left for me to do - to inform not very good news for all owners of the iPhone 5S, iPad 3, iPad Mini and older models. So, attention - it is impossible to put firmware on all these devices without a signature. No way. Even with the help special programs. Even for money. Even ... in general, at the moment such an opportunity is completely absent.

Everyone once reflashed their device for more new firmware. In most cases, new features are added to the firmware and bugs are fixed, but this does not always happen. Recently, after updates, some users start to “fall off” Wi-Fi, the network is lost, or the battery runs out for a couple of hours. Apple releases iOS updates not so often, during this time you can suffer enough with the problem that has appeared. In such cases, there are two options: wait for the update or roll back to the old iOS.

Officially rollback to previous iOS is not possible at the moment. Why and when Apple began to prohibit rolling back to the previous version of iOS, I will try to tell you.

The concept of SHSH (hash) appeared in 2009, along with the release of the iPhone 3GS.

SHSH- a digital signature that signs the firmware file before it is written to the device. The SHSH hash is issued by a special Apple server (gs.apple.com) in response to the flashing device ID sent to it by iTunes.

The scheme of interaction between iTunes and Apple servers:

Further, starting with iOS 3.1.1, the signing system was extended to iPod touch 2G and 3G, and since the release of iOS 4.0 SHSH, the iPhone 3G has also been subscribed. The iPhone 2G, iPod touch 1G and Apple TV 1G do not use SHSH, so these devices can always be flashed to any available version iOS.

The total control of the firmware was able to bypass the hackers. It turned out that SHSH with the Apple server can be requested not only by iTunes, but also by any other program. So it became possible to make a backup, and with this, in turn, roll back the firmware.

1. Programs that keep SHSH on your PC
2. Programs that store the hash on Cydia servers (in the cloud)

Both methods have their pros and cons. For example, programs that store your digital signature on Cydia servers sometimes crash or due to server overload, the hash simply cannot be saved. But each has its own advantages! For example, saving on a PC, SHSH will always be available to you, regardless of the performance of the Cydia servers or the availability of the Internet! Everyone chooses for himself what he likes, what is convenient for him!

Let me present some of the programs with which you can save SHSH:

Cydia

When you jailbreak your iOS device, Cydia is immediately installed - a tweak store. In addition to installing those same tweaks, Cydia will automatically save your firmware hash! Saving occurs when the Internet or Wi-Fi is connected.

Saving takes place directly from your iOS device to the Cydia server. The above shows that my iPod has SHSH stored since iOS 3.3.3. A little trick, if the hash is not saved automatically, just click the "Reload" button a couple of times.

The only negative this method conservation digital signature, this is a periodic server congestion. For example, after the release of Evasi0n, Cydia did not work stably and the Cydia servers were not up to it.

TinyUmbrella is one of the most famous programs for save SHSH from your PC, Mac. Main Feature this application is the ability to send your SHSH directly to the Cydia servers so that you do not lose the saved certificates on your PC in the future. Same way this program often used for the firmware downgrade itself. I will tell you about this in future articles!

iFaith (developer iH8sn0w) - Unique program, which allows you to save a hash from any iOS device running old version firmware that is not digitally signed by Apple.

When Apple stops signing old versions of firmware, there is no way to upload the hash, the iFaith utility allows you to dump SHSH files for any version of iOS and thereby restore to the iOS firmware you need!

Saving takes place on the PC in the location you specified, so SHSH will be available to you even when you do not have an Internet connection, but there is a save!

Instructions for use will appear later.

That's all you need to know about firmware rollback, this page will be updated as new information becomes available!!