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Re: [TLS] drop obsolete SSL 2 backwards compatibility from TLS 1.3 draft

Hauke Mehrtens <hauke@hauke-m.de> Sat, 27 December 2014 22:07 UTC

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Date: Sat, 27 Dec 2014 23:07:12 +0100
From: Hauke Mehrtens <hauke@hauke-m.de>
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Subject: Re: [TLS] drop obsolete SSL 2 backwards compatibility from TLS 1.3 draft
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On 12/24/2014 07:40 AM, Yoav Nir wrote:
>>
>> There's no reason to maintain any backwards support here just for Internet 
>> Explorer 2.0 on Windows 3.1.
>>
> 
> I’m not objecting to the change, but I am objecting to the hyperbole. The issue is with Internet Explorer 6 on Windows XP, which still exists, but more importantly, a lot of web service clients running on top of Windows XP use the same SCHANNEL library as IE would use, so they issue a SSLv2 ClientHello. Despite Microsoft’s best efforts, there is still a substantial but diminishing install base of XP.
> 
> It’s fine for us to break compatibility with these clients, but let’s not pretend it’s some ancient technology that doesn’t exist in the market anymore.
> 
> Yoav

In addition the Oracle Java Runtime Environment in Version 6 uses a SSL
v2 compatible ClientHello in the default settings. It supports SSL v3
and TLS 1.0. In Java JRE 7 a SSLv3 ClientHello is used by default.

I think a TLS 1.3 Client must not send a SSLv2 ClientHello, but a server
should understand it.

Hauke

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