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Re: [Dcrup] draft-ietf-dcrup-dkim-crypto-00

"John Levine" <johnl@taugh.com> Fri, 19 May 2017 15:13 UTC

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Date: Fri, 19 May 2017 15:13:11 -0000
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From: John Levine <johnl@taugh.com>
To: dcrup@ietf.org
Cc: fenton@bluepopcorn.net
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Subject: Re: [Dcrup] draft-ietf-dcrup-dkim-crypto-00
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In article <dd14eebb-a481-0d09-5d29-a245748ac700@bluepopcorn.net> you write:
>tl;dr: factored a 512-bit key on AWS in 72 hours for $75. But that was 5
>years ago. I haven't extrapolated to current compute costs/speeds or the
>longer key.

Doesn't the factoring effort double with every added bit?  That would
suggest that 1K keys are still impractical to factor unless you have a
great deal of money and a great deal of time.

We knew 512 bit keys were too weak in 2006, but we had (perhaps
misplaced) pity for people running beta libraries.

R's,
John

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