Re: [Teep] draft-tschofenig-teep-otrp-v2-00

[Anders Rundgren <[e-mail]>]

On 2019-07-09 15:59, Hannes Tschofenig wrote:
> Hi Anders,
> 
>> A wise decision!  BTW, I never understood the point making an IETF copy (it was?) of another standard.
> 
> Actually, it was the other way around.

Thanx, I didn't know that.

> 
>> I have said it before and I say it again: By separating the API from the Protocol and rather use a session-based scheme you get a cleaner and more powerful system [*] in the end.  Yeah, the initial task will be 30-50% bigger but that difference is zeroed out when you have both protocol encodings in place.
> 
> "Executive Level" description: https://cyberphone.github.io/doc/research/session-based-remote-attestation.pdf
> 
> Certainly a good point but I fear that it is not really design a secure system when the protocol does not terminate the secure world.

Every step of the protocol is supposed to be secured through MAC signatures.  If the protocol doesn't obey the API (which is running in the secure world [*]), the session terminates and the accumulated operations are rolled back.

Verifying my claims regarding the security of this scheme is non-trivial but it is not entirely different to TLS which you are an expert on.

Regards,
Anders

*] potentially extending into a security processor doing all cryptographic operations based on encrypted key material.

> 
> 
> Ciao
> Hannes
> 
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