let's say the "primecoin" example works because somehow it is magically easy to verify that a number is prime once you know it.
no but it's easy to determine that you've found a FACTOR to a number. what if these large primes are used to encrypt launch codes for nuclear weapons?
LOL. Why would a miner then even include transactions in a bitcoin block, if he's only interested in getting more large prime numbers?
presumably it would have to include some features of vanilla Bitcoin. -bm |
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Ken,
agree with you that some of the attitudes here are not constructive.
Doesn't the forum software filter out irrelevant posts that no one reads? Obviously this is a topic of great interest to the public, and not well presented. Unfortunately some here see this as a problem rather than an opportunity.
-bm
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I'm sure I'm missing something here (timestamp and previous block come to mind) but would it be possible to create a burst of transactions yourself -- enough to populate an entire block -- carefully designed to make the calculation of the hash quicker than accumulating transactions from the broadcast stream?
By adding transactions, you can change the merkle root part of the blocks, yes. There is so far no known way though to find out how to "design" this input to make the output more favorable for BTC mining, so currently only the nonce is generally changed when mining for some time. this would certainly violate the irreversibility principle behind SHA-256. |
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Hi Klm, Most of the criticisms offered on this thread are valid(more or less). Sukrim has made some good points. Proof of Work, is a concept that is designed to solve the problem of an unbounded consensus. In order to implement a Block Chain, you must have some way to determining consensus on what chain is the right one(because it can be forked). So there are many ways we can get this consensus. I came up with an alternative idea called Confidence Chains for instance. The way Bitcoin solves it is to say 1 VOTE PER CPU(rather than maybe 1 vote per IP address). That way, the theory goes, you cannot have sybil attacks and the network cannot be overpowered. This is a good paper on why there are problems with this approach: http://www.links.org/files/decentralised-currencies.pdf There are other ways to prove you have a CPU. For instance finding factors of large numbers. There are other requirements that must be fulfilled however. For instance *easy to verify*, that for instance prime number generation doesn't necessarily offer. I'm just posing the problem and putting it out there and see what kind of response there is. That's about it- my intentions are pretty innocent really. I think some of the frustrations are that this issue has been raised before. Thanks for your positive thoughts! -bm |
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The problem is that mining requires a work that is hard to find but easy to verify.
Prime numbers don't work because finding one is as difficult as verifying it's prime
I've already discussed this idea on another thread https://bitcointalk.org/index.php?topic=233750.msg2509289#msg2509289There are ways of reconstructing the problem so that it satisfies the pow requirements such as changing the problem to finding a factor of a large number. you basically restated what I suggest at the beginning of this thread, but two days later. |
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My assumption here is that they cannot be faked. Some projects pay for computation, why don't people game those systems?
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Careful how you use the term random there, its not a very accurate usage.
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the idea is this.
Instead of having hundreds of thousands of CPUs wizzing away at pointless SHA computations, we can use this principle of Proof Of Work to do something USEFUL.
these distributed computing projects need only modify their service slightly. If you compute something useful for them, then: they offer to sign your block, or give you a token you can use to create a block
this becomes your Proof of Work. The coin founders can decide what various programs are eligible and which ones are not, they can also determine what your block reward is.
YES, it violates the principle of decentralization, because you MUST get the signature of eg. SETI on your block for it to be valid, however it DOES fulfill all the other requirements for proof-of-work. It would optimally be a program that various distributed computing projects can participate in. It offers us a sort of decentralization, just not perfect decentralization(SHA256/nonce scheme is superior in this sense because it does not require a complex system to validate).
Thus we can have a PoW based currency that produces something useful. The coins have REAL WORLD VALUE that could even be backed by the programs themselves(some of them offer real payouts). We could solve major computing problems in a distributed and attractive way with this program.
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But you could turn it around into finding factors of a very large number to check whether it is prime. Couldn't you just lie about this? Imagine "15" is such a huge number: I just claim that the only factors I could find for 15 are 1 and 15, thus making it prime. This still requires you to try to find other factors to debunk my claim... A large number is proposed and everybody keeps dividing it by various primes until somebody gets lucky and finds a factor. It takes a lot of computational power to keep dividing but when you have found a factor anybody can quickly check whether it actually is a factor. these problems lie at the basis of the RSA function itself: http://en.wikipedia.org/wiki/RSA_%28algorithm%29#Integer_factorization_and_RSA_problem |
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But you could turn it around into finding factors of a very large number to check whether it is prime. Couldn't you just lie about this? Imagine "15" is such a huge number: I just claim that the only factors I could find for 15 are 1 and 15, thus making it prime. This still requires you to try to find other factors to debunk my claim... A large number is proposed and everybody keeps dividing it by various primes until somebody gets lucky and finds a factor. It takes a lot of computational power to keep dividing but when you have found a factor anybody can quickly check whether it actually is a factor. Then some formula using the previous number and the factor that has just been found is used to create the next big number to check. Of course there is the problem that if the number is actually prime we never find a factor. This isn't an answer just an idea of what sort of thing the pow problem might be. There is a lot of processing power out there working on hashing. What if a researcher wants to use this sort of distributed processing power for a useful research project? Everybody donates their processing power to the project and they are then entered into a lottery with the chances of winning related to how much processing power they donate. This lottery replaces the lottery of whether or not you come up with the right nonce. how about this: the currency is 'pre-mined' EXCEPT if you find a new prime number. The miners only get transaction fees. here is the twist: so if you think you discovered a prime number, you create a special block which grants you eg. 80,000 USD worth of primecoin. if someone discovers a factor to that prime, then you lose your block, your award, and anyone holding those coins also loses their balances(this would of course require extensive reordering of the BC- but it is effectively possible). This kind of tracing to a genesis transaction is done and proven with color coins. What does this create? it means that pseudoprimes would be a kind of currency, just not a very sound one. If you chose to accept value from a dubious pseudoprime, you risk losing your money. So this puts the onus on the person claiming the number, they might want to publish a reason why they think this number is prime. it would have an interesting effect, for instance the pseudoprimes that are located along features in the Ulam Spiral would have higher market rates than those that didn't. It would create an entire speculative market for prime computation. Kurt Godel would be ecstatic. In other words: you believe integer X is prime. You read a whitepaper that suggested so. So you buy some coins that are FOUNDED in that prime. If it is later proven to be prime, the market value goes up. If I'm a Integer Factorization Miner, and I think I can find a factor in it- I take out a short position- mine the integer, find a factor, publish, and the price plummets and I go buy a steak dinner. Has no one ever proposed this idea before? Primes are really the only true COMMODITY in mathematics. They are in limited supply but also unbounded. They are useful. They are hard to find. This lives up more to the promise of bitcoin than bitcoin itself. |
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if you were to find a way to speed-up hashing beyond just structured/standard-cell ASICS, the dumbest thing to do would be sharing your knowledge, you would ideally run your own little hashing farm and turn it on/off on demand to print money and "surf & ride difficulty".
or if you had such secret knowledge you could run a spy agency... hmm.... |
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I think you don't understand.
Checkpoints are not there to fight proof of work - they are there to protect your node from DoS attacks.
Do you understand that if there were no checkpoints, anyone with a graphic card could just keep mining blocks that link to the genesis one, and this way fill up your hard disk?
Do you understand that checkpoints completely violate the entire purpose of Bitcoin? What they do is introduce a form of approval(consensus) about the state of a chain. This form of authority could certainly be abused, and it runs counter to practically every design principle of Bitcoin. at the most fundamental level, the client code should not have ANYTHING to say about the block chain. Whether this is required in order to operate is irrelevant. The reason people use Bitcoin is *because* it's peer-to-peer. |
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P.S. No one particularly likes the checkpoints, the devs least of all. There has been much discussion about removing them, or switching to a soft system (config file, etc). So far, no one has come up with a really good solution.
I can come out with a really god solution, if you want  Just set a dynamic limit in that the client would not accept any forks deeper than N blocks back from its currently known top. Set N to whatever you want, but I think more than a week time would be exaggerating. the fact is, if we've introduced a form of consensus OUTSIDE of proof-of-work, that overrides Proof-Of-Work, and that's precisely what checkpoints are- why do we have proof of work at all? can we remove proof of work, and have a block chain that is based on consensus between N parties? Yes! https://docs.google.com/file/d/0BwUFHE6KYsM0ZkxLVmFwbXQ3ck0/edit?usp=sharing-bm |
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who makes the checkpoints?
The bitcoin core devs so ultimately, the state of the block chain depends entirely on them. not really. they only put checkpoint for blocks that are buried at least few hundreds deep already - unlikely to be reverted by honest means. but if you disagree with any checkpoint they add, just don't upgrade your node and you will be fine. well that's a practical solution, but it violates the notion of 'peer-to-peer' or equality for all nodes in the network. there is no indication of 'checkpoints' in the satoshi whitepaper. furthermore, if we rely on such checkpoints for security, why do we even have proof of work at all? Why don't we just rely on the checkpoints? |
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who makes the checkpoints?
The bitcoin core devs so ultimately, the state of the block chain depends entirely on them. |
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who makes the checkpoints?
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"There should not be any central source that affects the types of calculations" problem is that the Bitcoin is longer truly decentralized, so we've compromised this feature already- thus this particular requirement is possibly no longer relevant. Seems you're not aware of these details about Bitcoin. |
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I also would rather have someone pay me in Bitcoin (e.g. via these constantly adjusting microtransactions) for running a "useful" program than have this program generate bitcoins themselves.
that would perform a similar function, however this is more 'free market'. Youre making a market for computation.the problem with Bitcoin is that there is nothing keeping the price afloat. As many have explained, USD are valuable for more than simply FIAT, they are LEGAL TENDER, which is supported by our justice system. If there is a dispute about payment, then we appeal to our court to settle this dispute. Bitcoin has NONE of that. Secondly the value of a USD(presently) is related to the debt and good credit of the United States Government and the Federal Reserve. Ultimately, it's worth resides in these places. Again, Bitcoin has none of these qualities. so Bitcoin is, seemingly, a self-creating value loop. It technically *shouldn't* have any value. Perhaps there is some other party that is 'pumping' up the value, and fooling uneducated individuals into THINKING it's valuable? |
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Hold on here, lets pull back for a minute and think about what were talking about here.
So basically what Im suggesting is make a coin that awards a miner for doing USEFUL work- e.g searching for extraterrestrial life.
If you compute the data, its verified somehow that you've done it, then you get the block and the reward.
is it valuable? in this case SETI should make it valuable. For example you can use this coin to gain access to The Vanderbuilt Planetarium. You can use it to purchase Hubble Space Posters, etc. Thus there is a DEMAND for it. Once we have DEMAND, we have VALUE.
Once it has some kind of value, then it also has an exchange rate, and for instance our friend here can use it to eg. purchase pornography on Silk Road.
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