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Re: [TLS] RFC 7919 on Negotiated Finite Field Diffie-Hellman Ephemeral Parameters for Transport Layer Security (TLS)

Peter Gutmann <pgut001@cs.auckland.ac.nz> Fri, 19 August 2016 13:03 UTC

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From: Peter Gutmann <pgut001@cs.auckland.ac.nz>
To: Ilari Liusvaara <ilariliusvaara@welho.com>, "tls@ietf.org" <tls@ietf.org>
Thread-Topic: [TLS] RFC 7919 on Negotiated Finite Field Diffie-Hellman Ephemeral Parameters for Transport Layer Security (TLS)
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Date: Fri, 19 Aug 2016 13:03:22 +0000
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References: <9A043F3CF02CD34C8E74AC1594475C73F4CF009C@uxcn10-5.UoA.auckland.ac.nz> <20160816145548.GQ4670@mournblade.imrryr.org> <9A043F3CF02CD34C8E74AC1594475C73F4CF1AC9@uxcn10-5.UoA.auckland.ac.nz> <CADMpkc+vbkWz_TQ2Ch5JfaVRPse4qeXPPitsBV=d2yDtSx4eLA@mail.gmail.com> <9A043F3CF02CD34C8E74AC1594475C73F4CF416C@uxcn10-5.UoA.auckland.ac.nz>, <20160819125658.v6t4d6stpo6tk476@LK-Perkele-V2.elisa-laajakaista.fi>
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Subject: Re: [TLS] RFC 7919 on Negotiated Finite Field Diffie-Hellman Ephemeral Parameters for Transport Layer Security (TLS)
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Ilari Liusvaara <ilariliusvaara@welho.com> writes:

>AFAIK, that failure can only happen if at least one of:

[...]

New groups are introduced but the server or client only support the old ones.
So the server does ffdhe2048, the client does ffdhe2048', both are quite happy
to do DHE-2048 but as a result of complying with 7919 they're forced to use
RSA.

Peter.

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