Encrypting a Multicast Video Stream?

Samhain138 asks: "My company streams video via multicast in a pretty large network. They have a client program for viewing this video stream. Everything works fine, and since the stream is ISMA MPEG-4, almost any player would be able to view it. Lately, they've been looking for a solution for encrypting the video on-the-fly with minimal delay, however all of the solutions they've come across require something physical (dongle, smart-card) which may cause a problem (we can't physically reach all the viewers and it might also become expensive when we have a lot of viewers). Can Slashdot readers suggest anything that is simple to implement (or buy...)?"

IPSec

[Curien]

What about using IPSEC to encrypt the transmission?

-- DRM paranoia rant --

[samrolken]

Encrypting a video stream? Encrypting media content? What are you talking about, some kind of DRM system? On Slashdot? Seriously though, Windows Media supports ISO MPEG4 and some good DRM.... I mean... encryption. -- Sam Kennedy

How secure do you want it to be?

[John Harrison]

If your keys aren't in hardware such as a smart card then you aren't secure, you are just making people jump through hoops.

Even if your keys are in hardware you aren't secure since someone could just grab the stream after it is decrypted. So you probably need to decide what it is that you want to protect against and what it is that you aren't going to worry about stopping.

Re:Quick Solution

[swillden]

Stream ciphers do not fare well against lossy networks.

Stream ciphers are just fine in lossy networks, as long as your stream carries synchronization data in plaintext.

I have your answer right here:

[Anonymous Coward]

Three letters: VPN. It will encrypt and decrypt everything automatically w/o making any changes to the viewing program. Kind of a pain, but if you REALLY want/think it needs to be encrypted, it'll do the job.