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Re: Reasons for AH & ESP
On Sat, 27 May 2000, KokMing wrote:
> Hi,
>
> Does anyone know, or is able to explain the reasons for AH & ESP?
> As Neil Ferguson and Bruce Schneier wrote in 'Cryptographic Evaluation of
> IPsec', I too, find no reasons for two protocols in the RFCs.
>
> The reasons I think of is..
>
> 1. Cryptography is not exportable
> Well, it's more or less exportable now, and does the use of MD5 as a HMAC
> count as cryptography? I think not. Wouldn't it be better to have an ESP
> with compulsory AH authentication, and optional encryption?
>
> 2. It's more flexible
> IMHO, the flexibility of IPsec is killing it, the configurations are
> simply too numerous and complex for a layman (like me) to make head and
> tail, much less use it properly.
>
> 3. Finer grain of control
> As said, is it necessary? Will it make IPsec more secure against
> cracking? or spoofing? or nothing?
>
> I'm sorry if this has been dwelt on long ago, but I simply couldn't stand
> the mess IPsec is in, while I'm writing a paper about it, and I'll like
> some comments on my views.
I am not sure if any one is using AH and ESP this way, but this is one reasoning
I was given some time back.
RFC 2401 section 4.3 talks about combining security associations (iterated
tunneling). It talks of a case (case 2) where an end-point could apply ESP with
the outer gateway and AH with a host behind the gateway. Thus the packet could
be authenticated and encrypted over the internet and just authenticated inside
the network behind the gateway allowing for any traffic analysis.
>
> Regards,
> Kokming Ang
>
> ISRC
> Queensland University of Technology
> Brisbane, Australia
--
sankar ramamoorthi
email: sankar@nexsi.com
phone: 408-579-5718 (w)
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