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Re: [dane] DANE and STARTTLS - indication of availability of encryption

Viktor Dukhovni <viktor1dane@dukhovni.org> Wed, 04 September 2013 03:21 UTC

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Date: Wed, 04 Sep 2013 03:21:46 +0000
From: Viktor Dukhovni <viktor1dane@dukhovni.org>
To: dane@ietf.org
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Subject: Re: [dane] DANE and STARTTLS - indication of availability of encryption
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On Tue, Sep 03, 2013 at 06:31:33PM -0700, Ian Fette (????????) wrote:

> However, one of the problems with SMTP is that it's not known to
> the sending server whether the receiving server supports STARTTLS
> a-priori.  Similar downgrade vulnerabilities exist for other
> protocols that rely on STARTTLS-type commands.

This is well understood, and downgrade resistance is built into:

    https://tools.ietf.org/html/draft-dukhovni-smtp-opportunistic-tls-01

as well as the earlier:

    https://tools.ietf.org/html/draft-ietf-dane-srv-02

and not surprisingly into the Postfix DANE implementation, currently
available in the 2.11-20130825 snapshot from www.postfix.org or
from the Debian experimental package repository.

-- 
	Viktor.

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