Protected Streaming

Protected Streaming is a DRM-Technology by Adobe. It is used to protect digital Content (Video or Audio) from unauthorized use.

In fact, Protected Streaming consists of many different techniques; basically there are two main components:

Encryption:

All contents are encrypted by the Flash Media Server "on the fly". This means, there is no encryption of the source file needed (which is different to Microsoft DRM, for instance). For data transmission, a special protocol is used: rtmpe or rtmps.

rtmps uses SSL-encryption, rtmpe makes use of proprietary encryption algorithms. rtmpe causes less CPU-load than rtmps on the Flash Media Server, but the encryption has been hacked: There are existing tools to decrypt rtmpe streams and save the content unencrypted to a file.

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Edit (let someone else clean up the erroneous statement above): Apparently the hack is not violating rtmpe, but rather getting access to the decrypted data as read client of the FMS server and/or hacking into the Flash Player memory:

http://www.adobe.com/cfusion/webforums/forum/messageview.cfm?forumid=15&catid=578&threadid=1383125 http://paarijaataditya.blogspot.com/2008/08/capturing-content-streamed-by-flash.html

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Currently, there are no known hacks for rtmps and also there are no known tools to perform rtmps decryption. rtmps takes more CPU-ressources server-side, than rtmpe.

SWF-Verification

This technique is used to ensure that only the official Flash Client, delivered by the content owner, can be used to request the streaming data.

All officially allowed clients (which are in fact *.swf Files), need to be placed on the Flash Media Server. Any unknown client requesting a connection, will receive an "connection reject".

The combination of both techniques ensures, that streams cannot be sniffed and stored into a local file. SWF Verification is needed, to avoid that manipulated clients can access the content. Those clients could possibly write the unencrypted content to a file.

Besides that, it is possible to restrict connections to the Flash Media Server to a list of known hosts, to avoid that the whole player (the flash client) is placed on a foreign site.

References:

• [1] - Whitepaper von Adobe
• [2] - rtmpe (Adobe LiveDocs)
• [3] - rtmps (Adobe LiveDocs)