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Re: [Dcrup] rsa-sha1 usage

"Salz, Rich" <rsalz@akamai.com> Tue, 13 June 2017 12:05 UTC

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From: "Salz, Rich" <rsalz@akamai.com>
To: Peter Goldstein <peter@valimail.com>, "dcrup@ietf.org" <dcrup@ietf.org>
Thread-Topic: [Dcrup] rsa-sha1 usage
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Date: Tue, 13 Jun 2017 12:05:25 +0000
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References: <m38tkw53bd.fsf@carbon.jhcloos.org> <CABa8R6s6rzc+Ky8sLWcK7NtforSksEhNRkWVeF=k1v8GC80knw@mail.gmail.com> <m3wp8gpx20.fsf@carbon.jhcloos.org> <CAOj=BA2O+Hf2VGOtbmnqY2M5J9u8uJ7wm7SxEW551SXBwDdanw@mail.gmail.com>
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Subject: Re: [Dcrup] rsa-sha1 usage
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As a newcomer to DKIM (I come from the crypto side of things) I am a bit confused.

Certificates last for a couple of years, and so there was a strong motivation to move off MD5 and then SHA1, because of the concern that someone would find a collision and create a bogus certificate during the original cert’s lifetime.

But I’ve heard that DKIM “trust lifetime” is much shorter.  Is it?  What is the expected lifetime for relying on a DKIM signature?

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