Remote Audio Output Protocol

{{Infobox networking protocol

| title = Remote Audio Output Protocol

| logo =

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| is stack = No

| abbreviation = RAOP

| purpose = Internet streaming

| developer = Apple Inc.

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| based on = RTSP / RTP

| influenced =

| osilayer = Application layer (7)

| ports =

| rfcs =

| hardware = AirPort Express, Apple TV

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{{IPstack}}

Remote Audio Output Protocol (RAOP) is an Internet streaming protocol based on RTSP / RTP authored by Apple Inc.{{cite web |title=Unofficial AirPlay Protocol Specification |url=https://nto.github.io/AirPlay.html |website=nto.github.io |accessdate=20 October 2019}} It powers the AirPlay technology built into AirPort Express wireless (802.11b/g/n) access point as well as the Apple TV.{{cite web |title=Technical note to describe the Remote Audio Access Protocol (RAOP) as used in Apple iTunes to stream music to the Airport Express |url=https://github.com/xmms2/wiki/wiki/Technical-note-to-describe-the-Remote-Audio-Access-Protocol-(RAOP)-as-used-in-Apple-iTunes-to-stream-music-to-the-Airport-Express-(ApEx). |website=XMMS2 organization wiki |publisher=xmms2 |accessdate=20 October 2019 |date=7 October 2019}}

The major difference from RTSP is an initial asymmetric key verification made by iTunes to verify it is communicating with an AirPort Express or an Apple TV (as opposed to a simulation), and vice versa. The data channel is also encrypted by AES, with a random key protected by the asymmetric key mentioned above.{{cn|date=October 2019}}

The RSA public key stored in iTunes was extracted by Jon Lech Johansen, enabling third-party software to stream music to an AirPort Express.{{cite web|url=http://mailman.videolan.org/pipermail/vlc-devel/2008-December/054010.html |title=[vlc-devel] commit: Comment for myself ( Rémi Denis-Courmont ) |publisher=Mailman.videolan.org |date=2008-01-02 |accessdate=2012-02-10}}

The RSA private key stored in the AirPort Express was extracted by James Laird, enabling simulation of an Airport Express.{{cite web|url=http://mailman.videolan.org/pipermail/vlc-devel/2011-April/079148.html |title=[vlc-devel] RAOP/Airtunes |publisher=Mailman.videolan.org |date= 8 April 2011|accessdate=2012-02-10}}

The Shairport-sync application which emulates Airport Express hardware is available.{{cite web|url=https://github.com/mikebrady/shairport-sync |title=shairport-sync |publisher=github.com |date= |accessdate=2016-09-16}}