Re: [TLS] RFC-4366-bis and the unrecognized_name(112) alert

Martin Rex <> Fri, 04 June 2010 16:47 UTC

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From: Martin Rex <>
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To: (Michael D'Errico)
Date: Fri, 4 Jun 2010 18:47:04 +0200 (MEST)
In-Reply-To: <> from "Michael D'Errico" at Jun 4, 10 09:17:59 am
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Subject: Re: [TLS] RFC-4366-bis and the unrecognized_name(112) alert
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Michael D'Errico wrote:
> I would like to see text that says a peer SHOULD ignore warning alerts
> that it doesn't otherwise handle.  Clearly the peer that sent the alert
> with a warning level doesn't think it's a showstopper -- if it was a
> problem, the alert level would have been fatal.
> Peers that escalate a warning to fatal are not playing nice; they are
> causing other software to abandon the practice of sending warnings even
> though they could prove useful.  Just because you can't imagine why a
> warning alert would be useful, today, doesn't mean that a use will never
> be found for it.

I think we are talking past each other.

I do not have any problems with the existence of warning level alerts.

But defining only the situation when one peer can send a particular
warning level alert is entirely insufficient.  The definition of
a warning-level alert _MUST_ describe how the receiving peer is
supposed to react to this.  In most cases, a warning-level alert
indicates that something unusal happend on the last protocol
exchange, and there is no means _within_ the TLS handshake to resend
a previous handshake message with different properties -- which means
that we will may have to specify application/API semantics. 

For the warning-level unrecognized_name alert, I believe we have to specify
application/API semantics for the receiver.