Re: [TLS] No cypher overlap

Simon Josefsson <simon@josefsson.org> Mon, 03 August 2015 19:13 UTC

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From: Simon Josefsson <simon@josefsson.org>
To: Hubert Kario <hkario@redhat.com>
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Date: Mon, 03 Aug 2015 21:13:09 +0200
In-Reply-To: <2591292.9iByWAuqya@pintsize.usersys.redhat.com> (Hubert Kario's message of "Mon, 03 Aug 2015 13:36:22 +0200")
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Cc: Florian Weimer <fw@deneb.enyo.de>, tls@ietf.org
Subject: Re: [TLS] No cypher overlap
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Hubert Kario <hkario@redhat.com> writes:

> On Saturday 01 August 2015 23:16:42 Florian Weimer wrote:
>> * Hubert Kario:
>> > On Tuesday 28 July 2015 16:01:55 Viktor Dukhovni wrote:
>> >> In that case, it should be said that a client MUST NOT advertise
>> >> TLS 1.3 unless it offers at least one of the TLS 1.3 MTI ciphers
>> >> (or perhaps less restrictive at least one TLS 1.3 compatible cipher).
>> > 
>> > MTI does not mean Mandatory To Enable
>> 
>> Are you sure?  That's extremely surprising.
>
> yes, I'm sure:
>
> per https://tools.ietf.org/html/rfc5246#page-65
>
>>9.  Mandatory Cipher Suites
>>
>>   In the absence of an application profile standard specifying
>>   otherwise, a TLS-compliant application MUST implement the cipher
>>   suite TLS_RSA_WITH_AES_128_CBC_SHA (see Appendix A.5 for the
>>   definition).

I don't read anything about enable in deployments here?  Having code
implementing something does not prevent configuration (and even default
settings) to disable something.

/Simon