Cydia


Cydia is a package manager mobile app for iOS that enables a user to find and install software not authorized by Apple on jailbroken iPhones, iPads and iPod touch devices. It also refers to digital distribution platform for software on iOS accessed through Cydia software. Many of the software packages available through Cydia are free of charge, although some require purchasing.
Cydia is developed by Jay Freeman and his company, SaurikIT. The name "Cydia" is a reference to the moth genus Cydia, notably the codling moth, which is the proverbial "worm in the apple."

Purpose and function

Cydia provides graphical user interface to jailbroken users using Advanced Packaging Tool repositories to install software unavailable on the App Store. Cydia is based on APT, ported to iOS as part of Jay Freeman's Telesphoreo project.
Software packages are downloaded directly to the iOS device. Apps are installed in the same location as Apple's own applications, the /Applications directory. Jailbroken devices can also still buy and download apps normally from the official App Store. Most Jailbreaking tools install Cydia automatically, while others provide a choice to the user.

Software available through Cydia

Some of the packages available through Cydia are standard applications, while most packages are extensions and modifications for the iOS interface and for apps in the iOS ecosystem. Some apps available on Cydia are also emulators able to run images of games for old game consoles, albeit without those consoles' responsive controllers. Cydia enables users to find and install open source packages as well as purchase modifications for jailbroken iPhones. These modifications are based on a framework called Cydia Substrate, which makes it relatively easy to install and update said modifications.
UNIX command line tools are available on Cydia as well, including bash, coreutils and OpenSSH, meaning the device could potentially be used as a full-fledged UNIX workstation, although without many development tools.
In March 2009, the now-defunct blog TUAW announced that the Cydia Store, the in-app software purchasing system for Cydia, had opened for sales. The announcement also mentioned that Amazon payments was the only option available, but that PayPal would be added in the future, which it was. Cydia stopped accepting Amazon Payments in 2015, leaving PayPal as the sole payment option. After a bug related to PayPal digital token authorization was discovered which affected "very few users,” via TechCrunch, Freeman decided to shut down the Cydia Store on December 16, 2018.

iOS "signature" exploit

Cydia caches the digital signatures called SHSH blobs used by Apple to verify restores of iOS. Cydia's storage mechanism enables users to downgrade a device to a prior version of iOS by means of a replay attack. This means, for example, that a person with a jailbroken device who upgrades to a non-jailbreakable version of iOS can choose to downgrade back to a jailbreakable version.
iOS 5.0 and later versions of iOS implement an addition to the SHSH system, a random number in the "APTicket", making it more difficult to perform a replay attack, and thus more difficult to downgrade.

History

Freeman first released Cydia in February 2008 as an open-source alternative to Installer.app on 1.1.
In August 2009, Wired reports that Freeman claimed about 4 million, or 10 percent of the 40 million iPhone and iPod Touch owners to date, have installed Cydia.
In September 2010, SaurikIT, LLC, announced that it had acquired Rock Your Phone, Inc.. SaurikIT and Rock Your Phone were the two largest providers of third party apps.
On December 15, 2010, SaurikIT filed a dispute with World Intellectual Property Organization against Cykon Technology Limited of Kowloon, Hong Kong over the rights to the domain name "Cydia.com", which was registered in 2002. SaurikIT contended that Cykon registered the domain name in bad faith and the domain name incorporates SaurikIT's trademark. SaurikIT initially attempted to purchase the domain, then demanded Cykon to forfeit the domain at cost asserting trademark rights followed by bringing a WIPO proceeding. The complaint was denied by WIPO.
As of April 2011, Cydia had a $10 million in annual revenue and 4.5 million weekly users and according to Freeman $250,000 net annual profit.
On August 18, 2011, SaurikIT filed a lawsuit against Hong Kong owner of Cydia.com regarding the same domain name.
On May 14, 2013, Cydia Substrate for the Android operating system was released and supports Android versions 2.3 to 4.3.
On December 24, 2013, Cydia was updated to run smoothly on iOS 7 and iOS 7.1.
On June 12, 2014, Cydia was updated to version 1.1.10 to include a plethora of changes to further improve it and released Vietnamese language. Later that day, Cydia 1.1.11 was released with bug fixes. The following day, on June 13, 1.1.12 was released with more bug fixes.
On October 22, 2014, the Chinese jailbreaking team, Pangu Team, released an iOS 8 - 8.1 jailbreak. In response, Saurik quickly updated Cydia to 1.1.13, which added support for iOS 8 and pushed the update to apt.saurik.com for manual download. About a week later, 1.1.14 was released with bug fixes. Later that day, 1.1.15 was released with more bug fixes.
On November 5, 2014, Cydia was updated to version 1.1.16. This version included some minor bug fixes.
On October 28, 2015, The Pangu team released Pangu 9 giving access to Cydia from iOS 9-9.0.2
On February 6, 2017, Cydia was updated to run smoothly on iOS 10.2, and fixes the ability to make purchases.
On February 15, 2017, Cydia was updated to version 1.1.29 with bug fixes and performance improvements. On the following day, Saurik updated Cydia to version 1.1.30 to fix a bug that prevents users from installing purchased items in Cydia 1.1.29.
On February 26, 2018, CoolStar launched the initial release of Electra, giving access to Cydia from iOS versions 11.0-11.1.2. Alongside Electra for iOS 11, CoolStar released several patches for Cydia, creating a Cydia version compatible with the Electra jailbreak, as Electra had been released while Saurik was still working on updates for Cydia. Saurik eventually released the update, and pushed the update to iOS devices running iOS 11 with Cydia at the time. CoolStar’s patched version of Cydia turned out to be incompatible with Saurik’s new update, and as a result, multiple Electra users encountered errors and file corruptions.
On July 6, 2018 CoolStar updated Electra, granting access to CoolStar’s patched version of Cydia for iOS versions 11.2-11.3.1.
Saurik and CoolStar failed to reach an agreement regarding compatibility issues between Electra and Cydia. As a result, CoolStar and the Electra Team released their own package manager called Sileo.
In 2019, unc0ver was released for ios 12-12.4.1 for all devices with Cydia.
In 2020, a newer version of unc0ver was released for ios 13-13.3 for A12/A13 devices with Cydia.