In the end I'm not saying that would be a huge problem in that it would basically just jump us ahead 2 weeks but how possible is that for someone to pull off? It seems like a pretty good sized vulnerability. Especially if a couple large miners all decided to do it.
Doesn't seem simple to pull off: A timestamp is accepted as valid if it is greater than the median timestamp of previous 11 blocks, and less than the network-adjusted time + 2 hours. "Network-adjusted time" is the median of the timestamps returned by all nodes connected to you.
So to set a block's time considerably into the future one would have to control quite a portion of the network (>50%?), it seems. On the other hand, you don't seem to need to have a lot of compute power, if any. Unfortunately for the attacker: Network time is never adjusted more than 70 minutes from local system time, however.
So it seems quite impossible to pull off setting a block's timestamp into the future considerably. |
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What will happen if a node announces a block whose timestamp is false (i.e. earlier or later than the real creation time)? AFAIK, the difficulty is affected by the timestamps.
Difficulty is based on the number of blocks created, and is adjusted every 2016 blocks. no, difficulty is based on the number of blocks created /per unit of time/. Thanks for the correction. However, I'm going to add a trivial correction to your correction  Difficulty is based on how long it takes to generate the 2016 blocks. If it takes longer than expected (two weeks), the difficulty is reduced. If it takes less than two weeks, then the difficulty is increased. Without the constraints, though, if an attacker mined the 2016th block and put a timestamp a year in the future and that somehow got accepted, the difficulty would drop really low. Next thing to happen: the following 2016 blocks would be mined within a couple of hours and the difficulty would readjust to previous value after that. |
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As said before, it looks like I have actually convinced the german privacy foundation to accept donations using bitcoins.
Can someone verify they are currently not doing so?
I confirm that (but apparently they also accept cash). Also, for convenience of fellow non-German speakers who would also like to take a look, here's the Google Translate link. Ha, they finally did it (just received email from them): https://www.privacyfoundation.de/verein/spenden/Btw: I told them about the bounty and that I would donate half of it, should I receive it. I hope that doesn't disqualify me and I will receive the bounty for convincing an organization to accept Bitcoin for donations? They also told me the developers liked the idea of selling the CryptoStick for bitcoin, but don't currently have an interface to their shop-system. I will offer my help, of course. |
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Offtipic sorry, but I must say above article (even though I read it translated by google to english), is the most complete while condensed introduction to bitcoin I've seen so far. It has everything from a general description and motivation to details like Alpaca Socks... also mentions google. Quite a piece! |
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Probability is bitch  . Fortuna is a whore. |
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I'm aiming at the german pirate party ( http://piratenpartei.de) to convince them to accept BTC donations. Their donation page ( http://web.piratenpartei.de/spenden) doesn't currently mention bitcoin. Since they even talk about privacy concerns on the donation page, mentioning paypals long storage of payment information, Bitcoin should be quite a fit for them. It's a rather large organization, so it might be hard to get to the right people... we'll see. |
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Okay guys, I have put up the spreadsheets containing sponsors and persuaders. http://www.editgrid.com/user/mahkul/Earn_BTC_for_promoting_BitcoinLet me know if you see any mistakes in it - or, even more importantly, once the status should be changed from pending to complete. Also, please let me know your bitcoin addresses I should put in there. 1PwoVg3CxMkF7uVuAn3gcCp4SAtXwyxKuR <- my persuader address in case I get any bounty. Corrections for your spreadsheet: - I wouldn't count queeky.com as an organization. it's not a shop yet either, but they will sell premium accounts soon, so I'd put it as shop.
- the german privacy foundation is an organization that also has a shop (for their cryptostick)
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RapNews is awesome. To help you out a bit here, I emailed them asking for a Bitcoin donation address. (I'm not claiming any bounty) I also confirm they're currently not accepting bitcoin on their site. |
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YES
technically, it should be HALF, but for some reason I trust these people to put the "leftovers" into the next clip.
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Im a fan of the EFF. You're not alone, they've so far received BTC 2,340.46 on their donation address 1MCwBbhNGp5hRm5rC1Aims2YFRe2SXPYKt listed on https://www.eff.org/helpout |
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And getting one big payout was kind of fun. I may have to raise my threshold to 50 so I can simulate the experience of finding a block myself. It's just not the same when you're consistently progressing towards a goal with a known finish time. Sleepless nights of wondering "did I find a block just now?" for the win!  Well, I'm on day 12 now without a block @670 MH/s. Fortuna can also suck. Due to troubles with bitcoin spamming I reverted half my power to slush's pool. Feels weird to be back after 6 weeks or so mining solo. But also feels pretty safe and warm, just like home :p Steady progress has something soothing. |
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As said before, it looks like I have actually convinced the german privacy foundation to accept donations using bitcoins.
Can someone verify they are currently not doing so?
I confirm that (but apparently they also accept cash). Also, for convenience of fellow non-German speakers who would also like to take a look, here's the Google Translate link. Thanks for confirming. I overlooked they're accepting cash in the mail, too, yes. Is that a no-go for the bounty? |
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As said before, it looks like I have actually convinced the german privacy foundation to accept donations using bitcoins. Can someone verify they are currently not doing so? Here's their donation page, as you can see, only bankwire, creditcard and paypal are accepted: http://www.privacyfoundation.de/verein/spenden/ because I'd like to offer them half of the bounty as a little incentive and just to be nice, so I'd like to be able to actually claim the bounty once they accept bitcoin donations. Their google pagerank is 4, btw. |
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I'm going to contact the German Privacy Foundation ( http://privacyfoundation.de) They're selling a product, the cryptostick (smartcard on a usb stick), maybe I can get them to accept bitcoins in their shop or as donations. Don't start buying cryptosticks yet wait for them to accept bitcoins. If you'd like to get a cryptostick, ask if they accept bitcoins :p Don't know if they match the criteria, but will do anyways. Ha! They answered and said they were now testing bitcoin donations. They're even inclined to use it in their shop but have, of course, the exchange rate problem. Does anyone have some sample code I could point them to that grabs the exchange rate from mtgox / google (they think in EUR) so they could implement a live BTC price in their shop? Is there a good place to start for someone wanting to accept bitcoin in his shop and doesn't know where to start? A HowTo or something? |
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I'm describing the problem here from my personal perspective, bitcoind running on my desktop, which has a slow atom cpu and is frequently under various other load conditions), poclbm running on dedicated miner with a 5970. Problem is this: after running bitoind for a while, I see "Problems communicating with bitcoin RPC, data: None" messages on the miner. The freuqency of these increases over time (presumably with size of bitcoind's transaction cache). Getwork interval is at 5s. It has been suggested to used git-version with -limitfreerelay=1. I tried that and it might have taken some pressure, but the problem still occurs. After a couple of hours my miner doesn't do any work any more, because getwork continuously fails. I'm quoting from #bitcoin-dev to elaborate the problem and possible workarounds and/or solutions: <molecular> ArtForz, am running into slight getwork troubles at 66 tx cache size already? does that make sense? <ArtForz> nope <tcatm> molecular: what's the trouble? getwork taking long time to return? <ArtForz> do you have a really slow disk or high I/O load? <molecular> yes <molecular> getwork takes several seconds <molecular> at some point it takes longer the my getwork interval (currently 5s) <molecular> I have slowish cpu (atom) <ArtForz> yeah, that might do it <molecular> which is also under load from other shit since it's my desktop this made sense to me, ArtForz kept analysing: <ArtForz> can you check if it's actually pegging the CPU? <ArtForz> because here it seemed to be more I/O than CPU bound <molecular> I can't see it using cpu in htop. trying to verify that <molecular> there's some iotop app? what's it called? <ArtForz> iotop ? I'm emerging iotop on my desktop, while the chatter continues: <ArtForz> what stalls getwork is CreateNewBlock <ArtForz> and I suspect *that* is more I/O than cpu bound <ArtForz> I don't really know why though, it doesnt *look* like it does lots of I/O <molecular> CreateNewBlock is in O(n) with n == <number of tx in cache>? <ArtForz> yes <molecular> ArtForz, why do you think IO might be the problem? <molecular> it's all in RAM <ArtForz> yes, it does a fopen/fseek/fread/fclose for blk0001.dat <tcatm> so that's probably what slows it down <ArtForz> (if the input is from a tx thats already in a block) <ArtForz> and it does a lookup in blkindex DB for every call, too <molecular> "if (!txPrev.ReadFromDisk(txdb, txin.prevout, txindex))" <- you mean this, tcatm? <tcatm> molecular: yep <ArtForz> yeah, that sounds like it might cause slowdowns, especially if you dont have enough free memory to keep blk0001 cached <tcatm> how does that code find the transaction in blk0001.dat? is there an index for txhash -> blkhash? <ArtForz> yes <ArtForz> blkindex.dat for txhash->offset <ArtForz> urrr... why the F are we not caching that stuff? <molecular> slush, workaround will relieve the pain, but in the end we should fix stuff in bitcoin <ArtForz> it's not like tx can magically appear in blocks while no new block comes along <molecular> I think ArtForz might've just identified the root of the problem? <ArtForz> could be... <ArtForz> can't think of a elegant way to work around it though <ArtForz> thats... really weird <ArtForz> well, we do 2 things really with that prev tx <ArtForz> 1. check if it's in a block (can be cached between block updates) <ArtForz> 2. if it is, get the value of the output referred to (same thing) I'm stopping here and backposting link to #bitcoin-dev... |
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will try to convince queeky.com (online drawing) to accept bitcoins for their upcoming premium account selling and maybe donations.
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I'm going to contact the German Privacy Foundation ( http://privacyfoundation.de) They're selling a product, the cryptostick (smartcard on a usb stick), maybe I can get them to accept bitcoins in their shop or as donations. Don't start buying cryptosticks yet wait for them to accept bitcoins. If you'd like to get a cryptostick, ask if they accept bitcoins :p Don't know if they match the criteria, but will do anyways. |
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nice! I saw at least 2 of the creators have german-sounding names. Do you have a german translation yet? I'm working on one, it's harder than I thougt... Also: I might know someone (female) who might be willing to speak german audio for a low price... do we desire that? |
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Can't everyone who care about some arbitrary numbers and not the actual value just opt in to be paid in Venezuelan bolívars or something?
Or how about this: People with this psychological affliction can represent amounts in inflacoins (= BTC * 1.03^(year - 2009)) instead as they please. No need to change the underlying mechanics of the system.
As long as we don't build this crap into bitcoin itself, I don't care what people plug-in to it. It might well be that bitcoin will in fact be used to a great extent to back other currencies. I keep thinking: bitcoin is more like gold than like fiat currency. People might back their "fungusDollars" with bitcoin to bootstrap value. But it's still a long way to there. First, I think, we need bitcoin to be used for trading a lot more heavily. |
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Try changing the link options (LIBS=... variable) from static to dynamic. This has solved the problem for me. It seems that some packages in Gentoo require extra options to enable static linking, and I have not enabled them as I do not need them otherwise.
Thanks! That did the trick for me (gentoo). Likely could've also put "dev-libs/boost static-libs" in /usr/portage/package.use and reemerged boost. |
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