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Re: CGA Use with HBA in Shim6 IETF Meeting July 10, 2006
On 19-jul-2006, at 14:39, marcelo bagnulo braun wrote:
server certificate are more widely used than client certificates
indeed, but in the case of the shim6 we need certificates for both
ends, so what do we do for securing the client?
Why? If one end has a certificate the communication can be secure.
besides, currently deployed certificates provide binding between
FQDNs and public key.... while in the shim6 we need binding between
IP addresses and public keys, meaning than currently deployed
certificates are not good
Yes, this involves a trip to the DNS...
in addition, using certificates and public key crypto is much more
expensive than CGAs, since they would involve public key operations
not only for the validation of the locator set (as in CGA) but also
for the validation of the certificates themselves (and this costs
grows if the certification chain is long). In addition, there is
the overhead due to the transmission of the certificates in the
protocol itself, including all the certificates in the cert chain,
which may even not fit in a single packet so we may end up
neededing to send multi-packet messages.
and all this for every shimmed communication....
This is certainly true. On the other hand, if the communication is
already protected with TLS the _additional_ overhead isn't much.
Also, I think it would make sense to do the shim negotiation inside a
TLS protected TCP session, which should handle all the packet size
issues.
i thought that one of the key goals in the shim6 design was
efficiency.... such an approach would really move us apart from the
efficiency path...
HBA is much more efficient so that should stay security option #1,
but it would certainly be nice to have an alternative that allows
easier implementation of shim6 proxies and lets people avoid the
patent issues if they want.