RE: Algorithm Selections

I agree.  I'm no expert on this either but if we can adequately support
encrypted streaming video with block ciphers then that's fine by me, Ed

-----Original Message-----
From: Brian LaMacchia [mailto:bal@microsoft.com]
Sent: Wednesday, November 15, 2000 8:09 PM
To: 'Ed Simon'
Cc: 'xml-encryption@w3.org'
Subject: RE: Algorithm Selections


Ed--
 
Streaming video is fine, but I'm still not convinced that you'd want to use
a stream cipher to encrypt streaming video.  I'm not an expert on video
compression, but I'd expect you'd want to use a block cipher that is
re-keyed (or re-IV'd) in sync with however the compressed frames resync.
There's got to be some minimum quantum of compressed video that you lose if
there's any data loss, and within that minimum unit a block cipher w/ some
chaining mode will work just fine.  
 
                    --bal

-----Original Message-----
From: Ed Simon [mailto:ed.simon@entrust.com]
Sent: Wednesday, November 15, 2000 2:23 PM
To: 'xml-encryption@w3.org'
Subject: RE: Algorithm Selections


Jim and Brian and everyone,
 
I'm working on the assumption that encrypted streaming video will be an
application that is VERY desirable to support.  In particular, I expect
demand for encrypted streaming video to increase dramatically as high-speed
internet access become ubiquitous and with 3G wireless.  I admit I am
looking into the future a bit, but hey, that's what I like about standards
work ;-} 
 
Comments anyone?
 
Ed

-----Original Message-----
From: Brian LaMacchia [mailto:bal@microsoft.com]
Sent: Wednesday, November 15, 2000 4:29 PM
To: 'Ed Simon'
Cc: 'xml-encryption@w3.org'
Subject: RE: Algorithm Selections


Hi Ed,
 
I don't believe that streaming media/content necessarily requires use of a
stream cipher; I think that really depends on the particular application and
whether it wants to be able to recover from partial data losses in the
stream.  I can imagine particular scenarios where the application could
accept data loss (say a frame of video) and want to resync the keystream
with the encrypted data.  But I don't think these are the common scenarios,
so I'm happy to only require support for a block cipher in CBC mode (or some
other appropriate mode(s) TBD by NIST [1]).
 
                    --bal
 
[1] http://csrc.nist.gov/encryption/aes/modes/
<http://csrc.nist.gov/encryption/aes/modes/> 

-----Original Message-----
From: Ed Simon [mailto:ed.simon@entrust.com]
Sent: Wednesday, November 15, 2000 12:40 PM
To: 'xml-encryption@w3.org'
Subject: RE: Algorithm Selections


If XML Encryption is to be used for streaming media, as discussed in my
presentation at the work shop, then we will also need streaming ciphers.
 
Ed