Re: CRACK

[Dan Harkins <dharkins@xxxxxxxxxxxxxxxxxxx>]

On Fri, 22 Oct 1999 16:13:23 -0000 you wrote
> 
> Howdy ()

Ola ()

> 	Is this protocol self defeating of it's own goal? The goal is to allow
> the use of legacy authentication methods in place of deploying a pki.
> Yet this protocol requires the pre-existance of a pki. Is the answer
> along the lines of "yeah, but this is a small and manageable pki"?

The goal is to allow clients to authenticate using legacy authentication
methods. That the gateway requires a trusted public key does not make it
a self-defeating protocol.

> 
> 	In the crack draft, Section 2.2 says
> 
> -- 2.2 Exchange Definition
>  
>    This exchange is motivated by the use of roaming IPSec-enabled
>    clients which use legacy authentication methods for authentication
>    instead of using a public key certificate. 

Yes, the client does authenticates using the legacy authentication method.

> 	And section 3 says:
> 
> 
> 3. The Protocol
>  
>    This protocol uses digital signatures to bind each party to the
>    exchange as well as to the secret keying material that results from
>    the exchange.  The signatures are verified because the peers trust
>    each other's public keys.  This trust is acquired differently for the
>    client and the gateway.  The client trusts the gateway's public key
>    either because it came from a certificate which is signed by a
>    trusted certification authority or because the client trusts it by
>    some out-of-band mechanism (for instance it is loaded into his policy
>    store prior to embarking on his voyage).  

The client does not need a certificate. The gateway can. What is needed
is for the client to trust the gateway's public key. This is because "it
came from a certificate which is signed by a trusted certification authority 
or because the client trusts it by some out-of-band mechanism." So a pki
(even a small scale one) is not needed. Just some trust.

  Dan.