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Re: [TLS] The TLS_FALLBACK_SCSV time bomb

Florian Weimer <fw@deneb.enyo.de> Sat, 25 October 2014 17:09 UTC

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From: Florian Weimer <fw@deneb.enyo.de>
To: Andrei Popov <Andrei.Popov@microsoft.com>
References: <2112FCAD-4820-49D9-9871-6501C83A554D@cisco.com> <543F9893.806@redhat.com> <543FA0A0.1030205@polarssl.org> <543FCAED.50502@redhat.com> <2A0EFB9C05D0164E98F19BB0AF3708C71D39ECECB4@USMBX1.msg.corp.akamai.com> <5440E005.6000607@redhat.com> <180027849.13041583.1413544466157.JavaMail.zimbra@redhat.com> <CADMpkcL2mntDd0dOruziqF0F=xURnqGgd_YkpF+ONzz8v-wQ9Q@mail.gmail.com> <1354095824.13104897.1413553221955.JavaMail.zimbra@redhat.com> <CADMpkcLRCsfQSr0=f97kXJw3RwHN5A79MYQ2j7XaxPxUy2MCLg@mail.gmail.com> <CABkgnnUBYtWUY-CZDDzFiDpMWYbca74o6kejh2Q3L+FHVaHoOA@mail.gmail.com> <d8ce6c7437404bcbbea3a17e5c0b1582@BL2PR03MB419.namprd03.prod.outlook.com> <CADMpkcK4wCkLMU_Ga2fX3CWxXyU+D1Qgg1s77ttVq6LTo50XxA@mail.gmail.com> <loom.20141018T210052-775@post.gmane.org> <cd39914207d247008c0d054e71206efc@BL2PR03MB419.namprd03.prod.outlook.com> <CADMpkc+cC6WGZ8J-=exsjBnPPtvm0gs5_VaaSzKmjqXZyJNmug@mail.gmail.com> <ad51b80ad13342f4989448f21ede2538@BL2PR03MB419.namprd03.prod.outlook.com>
Date: Sat, 25 Oct 2014 19:08:55 +0200
In-Reply-To: <ad51b80ad13342f4989448f21ede2538@BL2PR03MB419.namprd03.prod.outlook.com> (Andrei Popov's message of "Tue, 21 Oct 2014 00:09:00 +0000")
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Subject: Re: [TLS] The TLS_FALLBACK_SCSV time bomb
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* Andrei Popov:

> Yes, and you should be able to get away without Downgrade-SCSV if
> you do not do fallbacks (which are not even part of the TLS
> protocol).

But you still have to patch servers to protect broken clients from
their foolishness.  It doesn't matter that you don't do downgrades on
the server side.  That's one reason why I think TLS_FALLBACK_SCSV is
an embarrassment—it sanctifies the sinners, instead of forcing them to
clean up their act.

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