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Re: I-D Action: draft-gont-6man-flowlabel-security-02.txt

Brian E Carpenter <brian.e.carpenter@gmail.com> Tue, 24 January 2012 01:18 UTC

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Date: Tue, 24 Jan 2012 14:18:23 +1300
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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To: 6man <ipv6@ietf.org>
Subject: Re: I-D Action: draft-gont-6man-flowlabel-security-02.txt
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Hi,

I really don't like the use of the counter in Fernando's proposed algorithm:

 Flow Label = counter + F(Source Address, Destination Address, Secret Key)

It seems to me that it introduces significant predictability for a malicious
observer of the packets leaving a given source.

Effectively the equivalent algorithm in RFC 6437 is

 Flow Label = F(Srce Addr, Dest Addr, Protocol #, Srce Port, Dest Port, Secret Key)

which is less predictable, even if the port number is not randomized.

I'll have more to say once a current investigation of algorithms by
a student is finished.

Regards
   Brian Carpenter

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