Hi.

As I’m the document author, it’s no surprise that my vote is Yes.

Much like Paul Wouters, I would have liked to have a kind of puzzle that did 
not give an advantage to attacking desktops over legitimate smartphones. But 
all proposals for puzzles have been just as CPU-bound as the partial hash break 
in the current draft, or the bitcoin-style puzzle that I like better now.

One proposal that I kind of liked (and I’m sorry I’ve forgotten who suggested 
it) was to relegate the puzzle to a second line of defense, through the use of 
some kind of anti-dos ticket. The ticket would be a bearer token (perhaps an 
encrypted timestamp) that would allow the bearer to get by with a much easier 
version of the puzzle. The responder would make an effort to prevent replay of 
tickets (as in remembering the last 1000 valid tickets), which would mean that 
to consistently get the easy version of the puzzle, the attackers would need to 
collect a greater amount of tickets than the responder stores.

In any case, I think the document should be adopted, and then we can change the 
puzzle algorithm according to the group’s preference and add a fast path for 
repeat visitors if we think that’s a good idea.

Yoav


On Sep 21, 2014, at 10:52 PM, Yaron Sheffer <[email protected]> wrote:

> Dear working group,
> 
> This is a call for adopting draft-nir-ipsecme-puzzles-00 as a WG document. 
> Please respond to this mail with a Yes or No and a short rationale, at latest 
> by Friday Sep. 26.
> 
> Thanks,
>       Yaron

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