Protected streaming
Protected Streaming is a digital rights management ( DRM technology ) from Adobe . It is used to protect digital content (video or audio streams) against unauthorized use. Protected streaming is actually a combination of different techniques. There are essentially two components that work together.
Encryption
The content is encrypted by the flash media server during transmission - no prior encryption of the files is necessary (in contrast to Microsoft DRM, for example). The data is transmitted using a special protocol, either rtmpe or rtmps . rtmps encrypts the data via SSL , whereas rtmpe uses a proprietary method. rtmpe creates less CPU load on the flash media server. In the past, a security leak in the Flash Player made it possible to access the transferred data. However, Adobe closed this vulnerability in January 2009. However, since the RC4 key used for encryption is calculated from the file itself to be transmitted on the one hand and the last 32 bytes of the first server response on the other, both a man-in-the-middle attack and decryption of the received media stream by the recipient is easy possible.
There are also tools that can decrypt rtmpe streams and also save them locally, for example rtmpdump . However, Adobe combats the public dissemination of these tools with reference to the DMCA .
SWF verification
This procedure is to ensure that only the official client provided by the provider can be used to retrieve the streams. With client is here z. B. means a Flash video player that is supplied by the content provider (for example, within a website). All permitted clients (.swf files) are stored on the flash media server. If an unknown client tries to access the stream, the Flash Media Server refuses to establish a connection to the client.
However, this cannot effectively prevent “listening” or “recording” the transmitted streams.
It is also possible to store a list on the Flash Media Server from which hosts the streams can be accessed. This serves to prevent the complete original player from simply being embedded in foreign pages.