[noise] Regarding Static Key Authentication

[Nadim Kobeissi]

Thank you, everyone!

Nadim Kobeissi
Symbolic Software • https://symbolic.software
Sent from office


On Tue, May 1, 2018 at 2:50 PM Marian Beermann <public at enkore.de> wrote:

> Hi Nadim,
>
> yes, if the intention is to have an AKE (authenticated key exchange),
> then the peer's static key needs to be authenticated in one way or
> another. Noise does not provide an out-of-the-box way to do that.
>
> -Marian
>
> On 01.05.2018 14:31, Nadim Kobeissi wrote:
> > Dear David,
> > So, the conclusion is that any `s` appearing in either a pre-message or
> > message pattern, is assumed to be authenticated out-of-band, as in
> > independently of the Noise handshake, by the recipient party?
> >
> > Thank you,
> >
> > Nadim Kobeissi
> > Symbolic Software • https://symbolic.software
> > Sent from office
> >
> >
> > On Tue, May 1, 2018 at 2:10 PM David Wong <davidwong.crypto at gmail.com
> > <mailto:davidwong.crypto at gmail.com>> wrote:
> >
> >     > If a token 's' appears in a Noise handshake pattern pre-message
> >     flight, it
> >     > is reasonable for us to assume that this key represented by 's' was
> >     > pre-authenticated by the parties. That is, if the initiator sent
> >     's' in a
> >     > pre-message, then the responder is assumed to have authenticated
> >     's' already
> >     > out of band, using for example a QR code as is the current
> >     use-case, for
> >     > example, in the Signal secure messenger.
> >
> >     I don't think this is a good comparison. Signal allows you to
> >     post-handshake authenticate the session whereas a pre-message `s`
> >     means that you have pinned `s` and thus you trust the session from
> the
> >     start.
> >
> >     `s` in a message pattern implies that you have a way to ensure that
> >     you know that `s`. This can be done in different ways:
> >
> >     * out of band post-handshake (like Signal)
> >     * by having the sender also send a signature from some authority that
> >     you trust (PKI)
> >     * by recognizing the cert from a trust store
> >     * ...?
> >
> >     Hope that helps,
> >     David
> >
> >
> >
> > _______________________________________________
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> > Noise at moderncrypto.org
> > https://moderncrypto.org/mailman/listinfo/noise
> >
>
>
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