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RE: Algorithm Selections

From: Brian LaMacchia <bal@microsoft.com>
Date: Wed, 15 Nov 2000 17:09:08 -0800
Message-ID: <0C682B70CE37BC4EADED9D375809768A0175464B@red-msg-04.redmond.corp.microsoft.com>
To: "'Ed Simon'" <ed.simon@entrust.com>
Cc: "'xml-encryption@w3.org'" <xml-encryption@w3.org>
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

 
Received on Wednesday, 15 November 2000 20:09:59 GMT

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