Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread John Dillon
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On Wed, Apr 17, 2013 at 9:48 AM, Mike Hearn m...@plan99.net wrote: So it'd be nice if this ended up not being necessary. Experience indicates that rational miners typically don't pursue a short-termist profit-at-any-cost agenda - free

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread Peter Todd
On Thu, Apr 18, 2013 at 06:07:23AM +, John Dillon wrote: Gavin do you actually agree with Mike on this stuff like he implies? Because if you do, I think people should know. Myself I wouldn't want to be contributing to your salary as a foundation member if you don't take Bitcoin security

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread Mike Hearn
When did I say DoS was unimportant? I just wrote a giant email explaining how it can be resolved. I think it's worth pointing out that Bitcoin was launched with no DoS protection at all, and it's still here. There are still obvious DoS bugs being fixed with every release. So yes, it's important

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread Peter Todd
On Thu, Apr 18, 2013 at 10:32:24AM +0200, Mike Hearn wrote: RE: shutting down services dependent on replacement. No, good users of replacement would still end up taking priority over the constantly churning DoS replacements. The most you can shut down is one contract. Obviously, if there's no

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread Peter Todd
On Thu, Apr 18, 2013 at 05:04:44AM -0400, Peter Todd wrote: An attack still shuts down useful tx replacement though. For instance in the adjusting payments example an attacker sets up a legit adjusting payment channel, does a bunch of adjustments, and then launches their attack. They broadcast

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread Mike Hearn
An attack still shuts down useful tx replacement though. For instance in the adjusting payments example an attacker sets up a legit adjusting payment channel, does a bunch of adjustments, and then launches their attack. They broadcast enough adjustments that their adjustment session looks

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread Mike Hearn
On Thu, Apr 18, 2013 at 11:28 AM, Mike Hearn m...@plan99.net wrote: With the sipaspeed patches it seems ECDSA can be processed on modern cores at something like 20,000 signatures per second. So it'd take a bit over 4 seconds to process all of them (cpu time). Sorry brainfart, s/cores/cpus/.

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread Mike Hearn
...and actually, that's not a problem if the defender is online, because they can just broadcast the highest sequence numbered tx, which blocks further broadcasts by the attacker. Good point - transactions can be ordered by highest version seen before they're signature checked. Even without

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread Peter Todd
On Thu, Apr 18, 2013 at 11:28:48AM +0200, Mike Hearn wrote: Let's include bandwidth. Say the contract (multi-sig input + the outputs) is about 700 bytes. 43,200 transactions is then about 29 megabytes of data. On a fairly normal 10mbit connection that would take about 23 seconds to transfer.

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread Mike Hearn
Indeed, as I mentioned in my first mail, nodes can be told how much bandwidth they're allowed to use and then prioritize within that, so I don't see any way convergence can fail. And regardless, I used 10mbit for the calculations, that isn't exactly unlimited. My home internet connection is better

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread Gavin Andresen
sure it's worth doing, at least immediately. Weakening the non-final == non-standard test to give a window of, say, 3 blocks, would be fine I think. Sure. I think Gavin wants some kind of wider memory pool limiter policy which would encompass such a thing already. Yes. I don't want to

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread John Dillon
I understand that Gavin has spent effort on security efforts against small-scale attackers. It's the fact that he is so dismissive of the threat that large attackers play that is what bothers me. But if I am being divisive I understand. I posted a clarification of what the reward is for exactly

Re: [Bitcoin-development] Anti DoS for tx replacement

2013-04-18 Thread Jeff Garzik
On Fri, Apr 19, 2013 at 12:38 AM, John Dillon john.dillon...@googlemail.com wrote: I understand that Gavin has spent effort on security efforts against small-scale attackers. It's the fact that he is so dismissive of the threat that large attackers play that is what bothers me. But if I am