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Re: [openpgp] Mining protection in fingerprint schemes

Vincent Breitmoser <look@my.amazin.horse> Sun, 10 April 2016 21:14 UTC

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Date: Sun, 10 Apr 2016 23:14:49 +0200
From: Vincent Breitmoser <look@my.amazin.horse>
To: Bryan Ford <brynosaurus@gmail.com>
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Subject: Re: [openpgp] Mining protection in fingerprint schemes
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Bryan Ford(brynosaurus@gmail.com)@Sat, Apr 09, 2016 at 12:55:42PM -0300:
> - V5 “key ID” is derived from the V5 fingerprint and shortened for presentation
> to the user - but shortened only to ~256 bits, not shortened to the point of
> insecurity like V3/V4 key IDs are.  That shortening could easily include simple
> Key ID mining-protection.

This was discussed before, but bringing this up again because I see you
saying 256 bit fingerprint for comparison like it's the natural
conclusion:

It's perfectly valid to go for stronger bitsizes in algorithms with the
argument that computers get better at crunching numbers all the time -
but humans don't. We should not increase the bit size here just because
that feels like the thing to do while revising a standard

Instead, we need to carefully consider the requirements for a string
used for authentication by manual comparison, the result of which I'm
pretty sure will be nowhere near 32 bytes of data.

 - V

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