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"FairPlay is a digital rights management (DRM) technology developed by Apple Inc. It is built into the MP4 multimedia file format as an encrypted AAC audio laye
by rntksi 6y ago
"FairPlay is a digital rights management (DRM) technology developed by Apple Inc. It is built into the MP4 multimedia file format as an encrypted AAC audio layer, and was used until April 2009 by the company to protect copyrighted works sold through iTunes Store, allowing only authorized devices to play the content."
"FairPlay-protected files are regular MP4 container files with an encrypted AAC audio layer. The layer is encrypted using the AES algorithm. The master key required to decrypt the audio layer is also stored in encrypted form in the MP4 container file. The key required to decrypt the master key is called the "user key".[1][2] When a user registers a new computer with iTunes, the device requests authorization from Apple's servers, thereby gaining a user key. Upon attempting to play a file, the master key stored within the file is then matched to the user key, and if successful, allows playing.[2] FairPlay allows unlimited music burns to CDs and unlimited music synchronization to iPods, but restricts listening to three Mac computers.[3]"
I still don't understand what would "FairPlay applications" entail? Anyone care to explain further?
- avaloneon 6y ago> I still don't understand what would "FairPlay applications" entail? Anyone care to explain further? Apps on iOS are kept encrypted until runtime, presumably to deter piracy. Obviously this makes reverse engineering/studying apps difficult, hence all the interest in a way to get unencrypted apps
- grishka 6y agoAnd as is usual with DRM, all it takes to defeat is one jailbroken device. Or, in this case, just one running an old enough iOS version.
- amaccuish 6y agoI think FairPlay is sort of a "brand" from Apple. There's "FairPlay" encrypted AirPlay streams, music files, apps, films etc. I don't think they all use the same underlying methods though.
- saagarjha 6y agoThat’s correct. iOS applications have their binaries encrypted by Apple when they are uploaded to the App Store, and a special memory mapper in iOS is used to copy those pages from disk and decrypt it into RAM so I can run. You can guess the obvious workaround for this: if you can read the memory of a process other than your own, just dump its memory and reconstruct the binary without encryption. This project allows this to happen on a device that isn’t jailbroken by using the PsychicPaper exploit, which allows applications to sign themselves with arbitrary “entitlements”, one of which is “I want to be able to dump memory from other processes”.