Looks like someone already necro'd this thread so I won't have to.  I stumbled across this thread while looking for something faster than pywallet to convert hexkeys to WIF privkeys and addresses... haven't quite gotten it running yet as it appears to depend on vim, which I don't usually have installed (vim provides xxd) just got it running after installing vim. It might be worth noting in the OP that it needs vim (and openssl, but I already had that) to run. Why would this depend on vim? I don't see vim called anywhere in the script. xxd is part of the Vim package. To avoid this dependency you can use perl as mentioned earlier in this thread. To spare you the hassle of looking for it: checksum() {
perl -we "print pack 'H*', '$1'" |
openssl dgst -sha256 -binary |
openssl dgst -sha256 -binary |
perl -we "print unpack 'H8', join '', <>"
} |
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I don't think that bitcoin and nations go well together in the first place.
Agreed. Bitcoin might very well bring anarchy to the world. For better of worse. Given the way governments operate, it could hardly be worse. Well, anarchy is not always fun, to say the least. |
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Notice that xxd might not be present on some Unix system. An alternative is to use the 'pack' perl function. Perl is always present on any decent GNU/linux/Unix system: checksum() {
perl -we "print pack 'H*', '$1'" |
openssl dgst -sha256 -binary |
openssl dgst -sha256 -binary |
perl -we "print unpack 'H8', join '', <>"
} |
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I don't think that bitcoin and nations go well together in the first place.
Agreed. Bitcoin might very well bring anarchy to the world. For better of worse. |
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I once heard someone ranting about how bitcoin does not make sense because its total amount can not be adapted to follow the amount of wealth created. To me this is as absurd as if someone decided to change the length of the meter because young people are statistically taller than their parents.
Money is several things, but amongst the things it is, it is a way of measuring quantities. It is a unit of account. And one does not change a unit of measure. You can use an other one, but you don't change it. When computers started to have disk space above thousands of mega-bytes, we did not decide to change the amount of bytes in one mega-byte, we used an other multiple of bytes and we talked about giga-bytes. That's how we use units.
An amount of bitcoins is a number. But this number has no meaning per se. It means something only when compared to a total amount. One bitcoin is truly one twenty-one-millionth of a fungible virtual set of things we call "bitcoins".
Now if these bitcoins are supposed to be used as an accounting system for the worldwide wealth, should the amount of bitcoins be increased when wealth increases?? Hell no, otherwise how do you even know that wealth has increased in the first place??
Really it's exactly as if we decided to increase the size of the meter because we noticed that young people are getting taller and taller. Being fix is the very purpose of a measure unit: because thanks to this we can compare it to things that are variable so we get an idea of how those things have changed.
Am I oversimplifying or something?
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Sorry my French is so bad I won't even try. Radio France International has just featured Bitcoin at our bar in Berlin (from min. 09:30) and I thought this should be posted here: http://www.rfi.fr/emission/20121227-accents-europe-27-decembre-2012From my own little knowledge of French I believe it is rather positive, your comments as native speakers are welcom! Best regards Joe Traduc: « Désolé mon français est si mauvais que je n'essaierai même pas. Radio France International vient de mentionner Bitcoin dans notre bar à Berlin (à partir de 09:30) et j'ai pensé que ça pourrait être posté ici. http://telechargement.rfi.fr.edgesuite.net/rfi/francais/audio/magazines/r155/accents_d_europe_20121227_1240.mp3D'après le peu de français que je connais ça m'a semblé plutôt positif, vos commentaires en tant que locuteurs natifs sont bienvenus. Salutations, Joe » La transcription de l'introduction du reportage: « Et en ces temps de crise des initiatives alternatives se multiplient, à Berlin on peut payer en bitcoins dans certains Bar. Une monnaie virtuelle qui existe depuis 2009. Les médias ne donnaient pas cher de sa vie pourtant le bitcoin a de plus en plus de succès comme a pu le constater Déborah Berlioz dans la capitale allemande: » Remarque personnelle: Reportage assez neutre qui laisse la parole au propriétaire du bar en question et à d'autres enthousiastes. Mais il laisse surtout le dernier mot à un économiste qui ne manque pas de nous dire que bitcoin est condamné à échouer compte tenu de son caractère déflationiste. |
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of course that won't make bitcoin unusable, even if you have to verify 1000 blocks. but if we want to make bitcoin more popular we also have to focus on usability. and i don't think many peolpe would be happy with a payment solution that takes 20min to load before you can use it.
i don't want to make bitcoin sound bad, i love the idea as much as most here do, i just want to point out that there is a lot of work to be done, especially on technical details of the software
I can agree with that. But there was someone in this thread barking that "your computer will just die"  |
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Imagine now that Bitcoin has 10k transactions per block instead of 200. Your PCs will just die.
All is fine as long if your PC can verify those 10k transactions in less than 10 minutes. From data on bloc 215475, I can read that a transaction is about 528 bytes long. So 10k transactions will be about 5.28MB of data. In ten minutes, that's an average of 8 kB per second. It might require improvement of existing software, but really it does not seem so difficult. Especially considering that consumer electronics keeps improving with time. yea, but what if average joe uses his client only once a week, he will then have to verify ca. 1000 blocks, what will take quite a lot of time Well, if bitcoin becomes so popular that it generates 10k transaction per minute, then I guess most users will make bitcoin transactions more often than once a week. I mean, supposing that bitcoin meets scale difficulties and yet that users use it very sporadically is a bit contradictory, isn't it? (it's an interesting question, though...) |
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Imagine now that Bitcoin has 10k transactions per block instead of 200. Your PCs will just die.
All is fine as long as your PC can verify those 10k transactions in less than 10 minutes. From data on bloc 215475, I can read that a transaction is about 528 bytes long. So 10k transactions will be about 5.28MB of data. In ten minutes, that's an average of 8 kB per second. It might require improvement of existing software, but really it does not seem so difficult. Especially considering that consumer electronics keeps improving with time. |
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You consider that common user home computer is able to serve the worldwide payment system?
Why not? Computers are quite powerful and humanity is not that large. |
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Allright. The client with DB consisting only with block headers receives the transaction. What next he must do with it?
Store? No. It must be sure transaction is valid to store it, but he can not check its validity as he dont have full chain.
Broadcast? No. Same reason. If trx isnt valid, he will be banned as DoS source by vanilla clients.
If network will consist of huge part of such light clients - it will be paralyzed.
I'm not talking about a header-only version of the client here. I'm talking about which part of the index it is useful to load in memory. |
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You know that spent transactions can be burried, don't you?
With the cost of security, don't you know? If client receive bcast block/transaction from network it must check its prev outputs in full block chain to know whether its a valid transaction for futher broadcast. If client burn old transaction - it will not be able to check new transactions for validity. If it broadcast not valid transaction - it will be banned by vanilla clients. So burning old block bodies makes client vulnerable to Sybill and DoS attacks. There is no security flaw in this. New transactions are not supposed to try to spend an already spent transaction. So it makes sense to remove spent transactions (only once buried under a few blocks though) from the index. They will still be in the database, but accessing to them will take more time. Though I'm no database expert, I'm pretty sure an index does not have to be exhaustive. |
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I'm not big expert in Berkeley DB, but it is obvious that one index record takes about 300 bytes in space. It's a sha256 hash + some index data. Remind me true number if you please.
So... To get index size greater than 4G we need only 13m transactions in whole chain. This is nothing for widely used payment system. For Bitcoin it is a 180 days of blocks containing 500 transactions each.
So Bitcoin is about to grow? Hehe.
You know that spent transactions can be ignored, don't you? |
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They key is index size, which is growing. Another key is number of broadcasted new transactions per time, which require database lookup to verify them.
As index size will run out of ~double avg RAM size of common computer - clients will start goxxxxxing on each incoming unspent trans. Because any disk caching mechanism will not be effective with such data and RAM sizes.
So every client on every incoming unspent trans will perform uncached disk lookup through gigabytes of data.
Hehe. I'm no expert in databases but it seems to me you don't know what you're talking about. Can someone confirm or infirm? |
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Is this for Bitcoin related stuff or just in general? Because if I had to pick one  Not necessarily bitcoin related. Any FOSS project you're interested in. |
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I'm talking about projects that currently exist or not. If they don't exist (as far as you know), they are projects you wish someone could start. If they exist, they are not mature enough and you are looking forward to see them become more complete. For me: - Perl 6. That's by far the FOSS project I currently feel the most enthusiastic about. - Minetest. The FOSS Minecraft clone. It currently pales when compared to its model, but it progresses fast. - Tribler. It currently works well enough to have become my main P2P client. Yet there is still lots of room for improvement. And many other functionalities could be imagined (a decentralised web architecture, for instance?) I may forget some, but those three are the one I think the most about these days. |
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The current decision of Ubanto's founding company, Canonical, of integrating desktop amazon searches by default, and the fact they send your queries to their own servers, for who knows what.
Still, even for people who don't like Ubuntu (I myself run a vanilla Debian distrib), I think it's still a good news because it might give an incentive for constructors to ensure their hardware is FOSS compliant. In other words, Ubuntu can be another troyan horse for free software. Again, I'm no expert in these things but that's how I see it anyway. |
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This is going to be quite off-topic. By the time I get my Bitcoin, the Calvin & Hobbes anthology is gone. In my entire life, I think I had never ever heard of this Calvin & Hobbes comics. Today I heard about it twice. The other one was in this Vsauce video, talking about the Calvin&Hobbes search engine. How weird. |
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Could the exact GPS coordinates be found if only three other GPS coordinates are supplied along with exact distance from each to the desired location? Or would that give you two possible locations?
I don't know much about GPS but to me it seems quite clear, from a purely geometric point of view, that there are two solutions to this problem. Since you probably try to locate a point on the surface of the earth and not in space, it's likely that only one of the two solutions is acceptable. |
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