Re: [Asrg] 3. Proof-of-work analysis

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In article <CB27C1AA-A8AB-11D8-B336-000393863768@chromatix.demon.co.uk>,
Jonathan Morton <chromi@chromatix.demon.co.uk> writes

>> We then
>> carefully worked through all the calculations, using the best data
>> that we could obtain -- and we did indeed come to the conclusion that
>> proof-of-work is not a viable proposal :(
>
>That's a very interesting paper, thank you.  I wonder, however, what 
>the distribution curves are like when "regular correspondents" are 
>exempted from proof-of-work, not just mailing lists.  Would it be 
>possible to re-examine the MTA logs for this type of pattern?

in principle yes ... however I doubt that the systems at the top of the
curve (sending lots of email per day) would have regular correspondents.
Besides the people running mailing lists, they will be e-commerce
systems sending acknowledgements, hospitals confirming appointments, fax
delivery systems relaying incoming messages etc.

However, I could not be sure of that statement without a fair amount of
processing. Since I'd like to know how much of the top of the curve
involves mailing lists, that's not processing that I'm averse to doing.

>By "regular correspondents" I mean people who know each other well 
>enough to send mail regularly, not necessarily frequently - even once a 
>week over a period of months.  I ask this because I expect that users 
>with slow machines - who would otherwise be the group most 
>inconvenienced by proof-of-work schemes - send mail that mostly falls 
>into this category.  I don't know, however, how much of the overall 
>picture is accounted for by these.

I don't see why one should expect any correlation between machine speed
and regularity of sending email. Many businesses will not splash out for
admin staff machines, so it is they as well as aged parents who might be
expected to have old kit :)

>For future work, it might be instructive to identify various non-spam 
>use-cases which appear to have a high proof-of-work load - ie. on the 
>"long tail" of the distribution curves presented - and consider 
>practical ways of relieving or accommodating it.

indeed so ... though you should note that there is not much difference
between spam viability thresholds and the average case, let alone power-
users.

For proof-of-work to look plausible (and not a high-risk strategy) I'd
like to see factors of a thousand or more between plausible workloads
for legitimate senders and any economically viable spamming activity :-(

- -- 
richard                                              Richard Clayton

They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety.         Benjamin Franklin

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