The AirPlay key was reverse-engineered by developer James Laird, who has published the information in an open-source emulator dubbed ShairPort. The tool, first discovered by MacRumors, can allow devices to receive AirPlay streaming content using Apple's native integrated capabilities in iTunes and iOS devices.
Laird took apart an AirPort Express and reverse engineered the AirPlay keys out of the device's read-only memory chip.
Audio streaming is possible through Apple's AirPort Express hardware, as well as the Apple TV. Previously, iTunes could stream to the official Apple AirPort express, and third-party tools like Rogue Amoeba's Airfoil, available for both Mac and Windows, could "hijack" audio and send it to an AirPort Express or Apple TV.
But now, with ShairPort, developers could allow a third-party device to accept a stream directly from iTunes, without the use of a tool like Airfoil. By utilizing the private AirPlay key, third-party software or hardware could be recognized by iTunes or an iOS device for direct streaming, without the need for additional software.
Apple does license its AirPlay standard to certain third-party vendors like Denon, Bowers & Wikins, Marantz, JBL and iHome, who have created devices like portable stereos that can accept an AirPlay stream. But ShairPort could be used to accept and play a wireless stream on a Mac, PC, or other hardware like an Xbox 360 game console.
It's unlikely that the key would be used in any commercially sold hardware, as Apple licenses use of the AirPlay standard for a fee. But the publication of the private key could allow custom hacks and configurations for users to set up at home on a variety of devices.
Last month, a report claimed that Apple is looking into the possibility of licensing AirPlay video streaming for third-party devices like high-definition TVs. Currently, the licensing associated with AirPlay only allows audio to be streamed to third-party devices.
But according to Bloomberg, Apple could open up AirPlay to allow the streaming of movies, TV shows and other video content -- something that is only currently possible with the Apple TV. Licensing the AirPlay video standard would allow users to stream video content from an iOS-powered device like an iPhone or iPad to a TV without the need for a hardware accessory like the Apple TV.