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Remote Audio Output Protocol
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<p>Remote Audio Output Protocol (RAOP) is an <a href="/facts/Internet_streaming/4rPhSq0Y">Internet streaming</a> protocol based on <a href="/facts/Real_Time_Streaming_Protocol/he6ChB16">RTSP</a> / <a href="/facts/Real-time_Transport_Protocol/YKQK1RK2">RTP</a> authored by <a href="/facts/Apple_Inc./oTJYta3k">Apple Inc.</a> It powers the <a href="/facts/AirPlay/ndx0rbhA">AirPlay</a> technology built into <a href="/facts/AirPort_Express/MluCU9hX">AirPort Express</a> wireless (<a href="/facts/802.11/ryEGu6Vq">802.11b/g/n</a>) access point as well as the <a href="/facts/Apple_TV/FHVJqBCw">Apple TV</a>. </p><p>The major difference from RTSP is an initial <a href="/facts/Asymmetric_key/gowoFTxS">asymmetric key</a> verification made by <a href="/facts/ITunes/pdXPE33T">iTunes</a> to verify it is communicating with an AirPort Express or an <a href="/facts/Apple_TV/FHVJqBCw">Apple TV</a> (as opposed to a simulation), and vice versa. The data channel is also encrypted by <a href="/facts/Advanced_Encryption_Standard/HdXGBY2Q">AES</a>, with a random key protected by the asymmetric key mentioned above. </p><p>The RSA public key stored in iTunes was extracted by <a href="/facts/Jon_Lech_Johansen/0NRkpF99">Jon Lech Johansen</a>, enabling third-party software to stream music to an AirPort Express. </p><p>The RSA private key stored in the <a href="/facts/AirPort_Express/MluCU9hX">AirPort Express</a> was extracted by James Laird, enabling simulation of an Airport Express. </p><p>The Shairport-sync application which emulates Airport Express hardware is available. </p>