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full file encyption RRS feed

  • Question

  • What's the design consideration of Media Foundation in the case of full file encyption, where the media source cannot get stream description or split stream without the decryptor (to decrypt at least part of a file)?

     

    Wednesday, January 17, 2007 10:17 PM

Answers

  • The assumption in Media Foundation is that the Media Source should be able to describe the presentation, and this description should be accessible even to non-protection-savvy code.

    (Note that as a corollary, Media Sources that have muxed streams are expected to demux them, and in particular that might mean doing a little demuxing even before Start() if doing so is going to be necessary to describe the streams -- i.e. mediatypes, etc)

    Tell me a little more about what you're doing... format, protection system, etc.  Are you really dealing with media files that are completely opaque (like you don't even know the mediatypes) until you get a license and decrypt it?

     

    Tuesday, January 23, 2007 4:01 PM

All replies

  • The assumption in Media Foundation is that the Media Source should be able to describe the presentation, and this description should be accessible even to non-protection-savvy code.

    (Note that as a corollary, Media Sources that have muxed streams are expected to demux them, and in particular that might mean doing a little demuxing even before Start() if doing so is going to be necessary to describe the streams -- i.e. mediatypes, etc)

    Tell me a little more about what you're doing... format, protection system, etc.  Are you really dealing with media files that are completely opaque (like you don't even know the mediatypes) until you get a license and decrypt it?

     

    Tuesday, January 23, 2007 4:01 PM
  • An example of what I described is to implement DTCP/IP under MF. The DTCP/IP packets are encypted. The Media Source is unable to demux the packets unless they are decrypted. If the decryption happens in the Media Source, that does not effectively use the PE protection. If the decryption is done within PE, Media Source, which is outside PE, cannot perform demuxing.

     

    Wednesday, February 7, 2007 4:20 PM