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RE: SOI: identity protection and DOS
At 5:06 PM -0500 11/26/01, Andrew Krywaniuk wrote:
> > Positive traits of IKEv1 pre-shared keys:
>> a) easy for each party to set up
>> b) not susceptible to CRL time lag or CA key compromise
>> c) fewer exponentiations on each side for IPsec key setup
>>
>> Negative traits of IKEv1 pre-shared keys:
>> d) hard to scale
>> e) unless identity protection is not needed, the initiator must be at
>> known IP address, and there must be only one pre-shared key at that
>> address
> > f) out-of-band swapping of the key must be done privately
>
>
>Some comments on this:
>
>(e) is only due to a flaw in IKEv1, and is unrelated to the use of preshared
>keys in general.
Yup. Some people think that identity protection is absolutely needed
in every circumstance, but most people would agree that identity
protection isn't worth preventing pre-shared secrets from working
with mobile users.
>(f) is not really valid because you need an out-of-band mechanism either
>way.
Not true. You only need a authenticated transport for the public key
hashes: you don't have to keep them private.
>(d) is the real reason for not using preshared keys.
...for some people. In many environments, scaling is not an an issue.
It is easy to argue that setting up simple CA and keeping its key
secret and issuing CRLs and so on for a 5-gateway WAN is more
difficult that passing around five preshared secrets on the phone.
--Paul Hoffman, Director
--VPN Consortium
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