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Re: [ntpwg] Parsing NTP packets regarding MACs and EXTs.

"Salz, Rich" <rsalz@akamai.com> Tue, 21 June 2016 16:52 UTC

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From: "Salz, Rich" <rsalz@akamai.com>
To: "mayer@ntp.org" <mayer@ntp.org>, Daniel Franke <dfoxfranke@gmail.com>
Thread-Topic: [ntpwg] Parsing NTP packets regarding MACs and EXTs.
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Date: Tue, 21 Jun 2016 16:52:13 +0000
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References: <stenn@ntp.org> <E1bFCJh-000G0C-Bf@stenn.ntp.org> <20160621093932.BD9A7406057@ip-64-139-1-69.sjc.megapath.net> <f4f6f8f969ac49ff819ccae06ec2e3db@usma1ex-dag1mb1.msg.corp.akamai.com> <d5934cd7-5808-3e2b-3ed6-b5e1b3f9e2df@ntp.org> <CAJm83bAHcSQtOHRjUHVk7o27KmbSqH_dad+dLMAhQ6Vh3hnsWw@mail.gmail.com> <d201d6d1-e769-c9c3-492c-409f129e54a9@ntp.org> <89190d0a867f4906b04431dda735cf8a@usma1ex-dag1mb1.msg.corp.akamai.com> <35fe3778-3580-001f-67a7-e91d3ef7584e@ntp.org>
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Subject: Re: [ntpwg] Parsing NTP packets regarding MACs and EXTs.
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Cc: "ntpwg@lists.ntp.org" <ntpwg@lists.ntp.org>, Hal Murray <hmurray@megapathdsl.net>
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> The intention is not to limit ourselves and AES-GCM is only one of the
> algorithms. The RFC needs to be updated but the reference implementation
> will support what's available and should be be flexible enough to switch
> algorithms in case any of them become regarded as vunerable.

Theoretically yes, but if AES-GCM is broken we'll all be using sundials anyway :)

I strongly recommend we look to what TLS is doing.  It has had the most attention from cryptographers of any IETF WG. For plaintext MAC, SHA256 HMAC.  For encrypted MAC, AES-GCM with chacha/poly as a backup.  Include an algorithm ID.

Do we have any reason to know that's not good enough?
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