IPSW, iPhone Software, is a file format used to install iOS,

iPadOS iPadOS is a mobile operating system developed by Apple Inc. for its iPad line of tablet computers. It is a rebranded variant of iOS, the operating system used by Apple's iPhones, renamed to reflect the diverging features of the two product ...

tvOS tvOS (formerly known as Apple TV Software) is an operating system developed by Apple Inc. for the Apple TV, a digital media player. In the first-generation Apple TV, Apple TV Software was based on Mac OS X. Starting with the second-generatio ...

HomePod The HomePod is a smart speaker developed by Apple Inc. The HomePod was designed to work with the Apple Music subscription service. The HomePod was announced on June 5, 2017, at the Apple Worldwide Developers Conference. Its launch was later de ...

, and most recently,

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac (computer), Mac computers. Within the market of ...

firmware In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide ...

for devices equipped with

Apple silicon Apple silicon is a series of system on a chip (SoC) and system in a package (SiP) processors designed by Apple Inc., mainly using the ARM architecture. It is the basis of most new Mac computers as well as iPhone, iPad, iPod Touch, Apple ...

. All

Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus '' Malus''. The tree originated in Central Asia, where its wild ances ...

devices share the same IPSW file format for iOS firmware and their derivatives, allowing users to

flash Flash, flashes, or FLASH may refer to: Arts, entertainment, and media Fictional aliases * Flash (DC Comics character), several DC Comics superheroes with super speed: ** Flash (Barry Allen) ** Flash (Jay Garrick) ** Wally West, the first Kid F ...

their devices through

Finder Finder may refer to: * Finder (surname) * Finder (software), part of the Apple Macintosh operating system * ''Finder'' (comics), a comic book series by Carla Speed McNeil * ''Finder'' (novel), a 1994 novel by Emma Bull * Finder Wyvernspur, a fi ...

or iTunes on

Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

, respectively. Users can flash Apple silicon Macs through Apple Configurator 2.

Structure

The .ipsw file itself is a compressed

archive file In computing, an archive file is a computer file that is composed of one or more files along with metadata. Archive files are used to collect multiple data files together into a single file for easier portability and storage, or simply to compre ...

(renamed Zip archive) containing at least three

Apple Disk Image Apple Disk Image is a disk image format commonly used by the macOS operating system. When opened, an Apple Disk Image is mounted as a volume within the Finder. An Apple Disk Image can be structured according to one of several proprietary disk i ...

files with one containing the

root file system In a computer file system, and primarily used in the Unix and Unix-like operating systems, the root directory is the first or top-most directory in a hierarchy. It can be likened to the trunk of a tree, as the starting point where all branche ...

of the OS and two ram disks for restore and update.

, audioOS and

also include a disk image for the recovery environment (recoveryOS). The file also holds the kernel caches, and a "Firmware" folder which contains iBoot, LLB (Low-Level Bootloader), iBSS (iBoot Single Stage), iBEC (iBoot Epoch Change), the Secure Enclave Processor firmware, the Device Tree, Firmware Images (Apple logo, battery images, Recovery mode screen and more),

baseband In telecommunications and signal processing, baseband is the range of frequencies occupied by a signal that has not been modulated to higher frequencies. Baseband signals typically originate from transducers, converting some other variable into ...

firmware files in .bbfw format (renamed zip file), and other firmware files. There are two more files named "BuildManifest.plist" and "Restore.plist", both

property lists In the macOS, iOS, NeXTSTEP, and GNUstep programming frameworks, property list files are files that store serialized objects. Property list files use the filename extension .plist, and thus are often referred to as p-list files. Property list ...

that contain compatibility information and SHA-256 hashes for different components. BuildManifest.plist is sent to Apple's TSS server and checked in order to obtain SHSH blobs before every restore. Without SHSH blobs, the device will refuse to restore, thus making downgrades very difficult to achieve.

Security and rooting

The archive is not password-protected, but iBoot, LLB, iBEC, iBSS, iBootData and the Secure Enclave Processor firmware images inside it are encrypted with

AES AES may refer to: Businesses and organizations Companies * AES Corporation, an American electricity company * AES Data, former owner of Daisy Systems Holland * AES Eletropaulo, a former Brazilian electricity company * AES Andes, formerly AES Gener ...

. Until

iOS 10 iOS 10 is the tenth major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 9. It was announced at the company's Worldwide Developers Conference on June 13, 2016, and was released on September 13, ...

, all the firmware files (including the root file system and Restore and Update ramdisks) were encrypted. While Apple does not release these keys, they can be extracted using different iBoot or

bootloader A bootloader, also spelled as boot loader or called boot manager and bootstrap loader, is a computer program that is responsible for booting a computer. When a computer is turned off, its softwareincluding operating systems, application code, an ...

exploits, such as limera1n (created by

George Hotz George Francis Hotz (born October 2, 1989), alias geohot, is an American security hacker, entrepreneur, and software engineer. He is known for developing iOS jailbreaks, reverse engineering the PlayStation 3, and for the subsequent lawsuit brou ...

, more commonly known as ''geohot''). Since then, many tools were created for the decryption and modification of the root file system.

Government data access

After the

2015 San Bernardino attack On December 2, 2015, a terrorist attack, consisting of a mass shooting and an attempted bombing, occurred at the Inland Regional Center in San Bernardino, California. The perpetrators, Syed Rizwan Farook and Tashfeen Malik, a married couple ...

, the FBI recovered the shooter's iPhone 5C, which belonged to the San Bernardino County Department of Public Health. The FBI recovered

iCloud iCloud is a Personal cloud, cloud service from Apple Inc. launched on October 12, 2011 as a successor to MobileMe. , the service had an estimated 850 million users, up from 782 million users in 2016. iCloud enables users to sync their data to t ...

backups from one and a half months before the shooting, and wanted to access encrypted files on the device. The U.S. government ordered Apple to produce an IPSW file that would allow investigators to brute force the passcode of the iPhone. The order used the

All Writs Act The All Writs Act is a United States federal statute, codified at , which authorizes the United States federal courts to "issue all writs necessary or appropriate in aid of their respective jurisdictions and agreeable to the usages and principle ...

, originally created by the

Judiciary Act of 1789 The Judiciary Act of 1789 (ch. 20, ) was a United States federal statute enacted on September 24, 1789, during the first session of the First United States Congress. It established the federal judiciary of the United States. Article III, Sec ...

, to demand the firmware, in the same way as other smartphone manufacturers have been ordered to comply.

Tim Cook Timothy Donald Cook (born November 1, 1960) is an American business executive who has been the chief executive officer of Apple Inc. since 2011. Cook previously served as the company's chief operating officer under its co-founder Steve Jobs. ...

responded on the company's webpage, outlining a need for encryption, and arguing that if they produce a

backdoor A back door is a door in the rear of a building. Back door may also refer to: Arts and media * Back Door (jazz trio), a British group * Porta dos Fundos (literally “Back Door” in Portuguese) Brazilian comedy YouTube channel. * Works so titl ...

for one device, it would inevitably be used to compromise the privacy of other iPhone users:

References

{{reflist, 30em

Structure

Security and rooting

Government data access

References

External links