Re: [Cfrg] When TLS is an overkill...

["Stanislav V. Smyshlyaev" <[e-mail]>]

Dear Max,

Just a quick comment: have you had a chance to have a look at the protocol
(also a SIGMA-based one) described in
https://tools.ietf.org/html/draft-selander-ace-cose-ecdhe-11? It may not be
the silver bullet but is definitely worth considering when thinking about
such questions.

Best regards,
Stanislav

пн, 25 февр. 2019 г. в 18:56, Dr. Pala <[e-mail]>:

> Hi CFRG,
>
> I am working on some aspects about provisioning credentials and
> authenticating devices and I noticed that sometimes people use TLS to
> establish a secure channel with a server even when all they want to do
> (i.e., no extra features/checks/etc.) could potentially be achieved in just
> 2/3 messages. An example of this is EAP - whenever a secure channel needs
> to be established, EAP-TLS, EAP-TTLS, EAP-TEAP, etc. must be supported to
> tunnel the 2nd method that will be used for authentication.
>
> My question for the group is: if we were to use a "simple" way to
> establish the secure channel, are there recommendations for what should be
> in those messages ? What would be the minimum set of required data that
> MUST be included in the exchange ?
>
> A rough example of such messages could be (A = Client, B = Server):
>
>    - [A] { Supported Encryption Algorithms List,
>           Supported Key-Exchange Algorithms List,
>           Encryption Initialization Data,
>           MSG Authentication } -> [B]
>
>    - [B] { Selected Encryption Algorithm and Params,
>           Selected Key-Exchange Algorithm and Params,
>           Key-Exchange Params (e.g., ECDHE),
>           (Optional) Credentials (e.g., Certificate Chain),
>           Encryption Initialization Data,
>           MSG Authentication } -> [A]
>
>    - [A] { Selected Encryption Algorithm and Params,
>           Selected Key-Exchange Params (e.g., ECDHE),
>           Key-Exchange Params (e.g., ECDHE),
>           (Optional) My Credentials Encrypted (e.g., Certificate Chain),
>           MSG Authentication } -> [B]
>
> From now on, the two parties end up with a shared secret key and
> agreed-upon encryption algorithm.
>
> In environments where the number of exchanged messages matter - EAP is a
> great example of that - having a standardized method that provides the
> possibility of establishing a secure communication channel very easily
> would be great. After that, I think that either the TLS layer can kick in
> and manage the encryption or other options might be used for the encryption
> of the data itself (e.g., directly encrypting the data record by record).
>
> Looking forward to hearing from you,
>
> Cheers,
> Max
>
>
> --
> Best Regards,
> Massimiliano Pala, Ph.D.
> OpenCA Labs Director
> [image: OpenCA Logo]
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