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Re: [RPSEC] rate limiting management traffic, redux
On vrijdag, apr 18, 2003, at 22:08 Europe/Amsterdam, Stephen Kent wrote:
In other words: yes, your integrety check is cheaper than full AH,
but is it worth the trouble to implement a new protocol in hardware?
If I were buying crypto hardware, I'd rather have it do full line
rate IPsec.
No disagreement about what would be ideal, just a matter of complexity
and cost, which I have been told are concerns for some folks :-)
They are. Maybe we'll see hardware that can do line rate crypto in some
places in the forseeable future, for instance at the edges to protect
against denial of service. But I'm pretty confident most people will
not be happy doing line rate crypto on a 40 Gbps linecard just to
protect a 1 Mbps max BGP session.
Currently IPsec ESP supports authentication and encryption, maybe
this could be an additional IPsec service?
ESP mandates support for confidentiality plus integrity, or integrity
only, or confidentiality only. Since the IPsec WG is trying to
simplify the range of options, we're dropping mandatory support for
confidentiality only. I don't see it as likely that we would add an
"authentication tag not tied to the payload" option.
Does it make sense to reinvent the wheel here? Especially as we can at
least reuse the anti-replay counter and possibly borrow some space from
the initialization vector to store the tag. Obviously this mechanism
would be entirely optional.
A tag formed from a truncated hash function output has the advantage
that an attacker is not able to see all the output bits to try to work
backwards to the key. But, we have not yet specified the function we
will use to generate the tag, and so it's a bit premature to talk
about whether a truncated output from that unspecified function is
appropriate :-).
Agree. I was just pointing out that a bigger tag isn't necessarily
better.
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