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Re: mail signing history, was Call for Community Feedback: Retiring IETF FTP Service

Michael Thomas <mike@mtcc.com> Wed, 18 November 2020 21:48 UTC

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Subject: Re: mail signing history, was Call for Community Feedback: Retiring IETF FTP Service
To: ietf@ietf.org
References: <01RS5CFAY5S0005PTU@mauve.mrochek.com> <20201118211937.01A22278DC6F@ary.qy> <01RS5Q2L2D6Y005PTU@mauve.mrochek.com>
From: Michael Thomas <mike@mtcc.com>
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Date: Wed, 18 Nov 2020 13:48:16 -0800
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On 11/18/20 1:26 PM, ned+ietf@mauve.mrochek.com wrote:
>
> FWIW, I actually pointed out this and other potential downsides of using
> signatures way back when DKIM was originally standardized, but (a) We don't
> have an alternative technology, or even an idea of what an alternative
> technology would be, and (b) As you say, we didn't expect it to be this bad.
>
> There's also no way to fully mitigate the issue: Someone can always immediately
> apply an independent timestamping service to every message they see, making
> subsequent exposure of the private key meaningless.
>
> That said, a mechanism for publishing/expiring DKIM private keys is something
> the IETF might want to standardize.
>
I really don't see the point of it. Mail providers' motivations are very 
different than individual users. I don't see how you can align those 
motivations easily to meet whatever the goal is.

Mike

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