|
549 Euros for a card w/ retail price of $500? Ouch. Guess some people had to have it.
|
|
|
|
That factor is determined exactly by difficulty*4295032833.
That is how much harder it is to find a block nonce at a given difficulty vs. verifying it.
Thanks for quantifying it. |
|
|
|
|
Of course (can't believe I missed that). So yeah it is more like a million fold (maybe billion fold) easier to verify than produce.
|
|
|
|
Is breaking SHA256 the only way to bypass proof-of-work?
Yes. By breaking I mean a pre-image or round reduction attack. The "work" is taking the hashed block header, double hashing it, and checking if the result in smaller than the target. It is that simple. We know that based on probability that on average it will take 2^32 attempts to find a hash below the target at difficulty =1. To do it in less than 2^32 attempts would require some pre-image or round reduction attack on SHA-256. |
|
|
|
|
lolwut asked me to and I am willing to hold escrow.
|
|
|
|
If you were smart enough to break SHA-256 and could mint money on a handful of low end computers don't you think you would be smart enough to a) spread the blocks around (i.e. purchase some dedicated servers around the world) b) include all transactions. If that had been done nobody would even know "mystery" existed. Likely any TH/s rise would be explained away as new BFL Singles coming online. So someone is smart enough to break SHA-256 an algorithm which entire crypto world has been trying to attack for a decade and yet not smart enough to blend into an anonymous network. http://en.wikipedia.org/wiki/Occam's_razor |
|
|
|
Not enough. On 820K LUTs if your placement was no more efficient then Spartan-6 boards maybe 1 GH/s. Spartan-6 is kinda hard to place though so maybe you get 50% better (50K LUTS per SHA-256 loop). Routing is greatly improved so a 4ns critical path is plausible. That means running the chip at 250Mhz. Ballpark we are talking ~ 1.8GH/s. If you could achieve 3ns critical path you might get that up to 2.4GH/s. That is on the largest Stratix IV which runs ~$8K. You would have a higher cost per MH/s on the smaller chips. That was all back of napkin guestimate. Don't go buying $9K chips based on that.  The power of Stratix line comes from the ability to perfect a design on a $9K chip which can be reprogrammed at will. Once you perfect that hypothetical 2GH/s you build a half dozen and torture test them. $100K investment sounds like a lot but honestly it isn't compared to the huge fixed costs and large run sizes of sASICS. It allows your team to perfect the design, tweak out any PCB issues, bugs, glitches, power and cooling concerns, etc. Catching a problem here is relatively cheap. You can get new prototype boards with 3 day turn around for <$100. Remember the goal isn't to be economical. It is all about perfecting a design as quickly and cheaply as possible. Once you are completely satisfied with final design and your investors sign off, Alterra would "clone" that bitstream to produce a mask for etching sASICS. The mask is going to cost you $100K+ (my number is probably dated, it might be triple that). The good news is the sASIC of the same chips is likely less than $2K each in bulk and probably uses 33% to 50% less power. Still you are looking at a minimum order of 1,000 units and 5,000 units would be more cost effective. There is no "do over" on a sASIC. If your chips have some critical flaw which produces invalid hashes under certain conditions well you got $10M in defective chips (it happens sometimes even to Intel). With those kind of numbers I think you can see how getting it right on a "cheap" $9K chip makes sense. Chips like Stratix are designed to allow low cost, low risk PROTOTYPING not retail use. Only if the market segment is so small that you could never sell more than a hundred units or so (like some high end enterprise networking devices) would you use the chip in a retail product. |
|
|
|
Isn't this just a 'guess' since hashrate is calculated based on block solving rate? If someone has bypassed the proof of work, we would be calculating the hashrate incorrectly.
However if someone has broken SHA-256 and can solve 3 blocks per hour with a handful of computers why not buy 10 handful of computers and solve 30 blocks per hour? He wants money but only the amount of money that 1.4TH/s "effective" produces. Not less money and not more money he has just decided that is the right amount. Seems implausible at best. If nothing else one would expect greed to creep in. If you had a method to print $750 per hour you wouldn't be tempted to "boost" that to say $1000 per hour or $1250 per hour? Nope. Not going above $750 per hour. Also not going lower to reduce suspicion, and not going to include tx which really makes me stand out. |
|
|
|
or those users could simply include fees and increase the economic incentive for miners to process them promptly. If fees were high and the miner was still excluding them I would be inclined to agree. Still I don't think "mystery" actions are affecting Bitcoin users in any meaningful way. 1 confirm time has increased from 10 minutes to 11.5 minutes but most users look at 6 confirm time. That has increased from 60 minutes to 61.5 minutes. A 2.5% slowdown and well within the normal variance of confirmations so that an uninformed users wouldn't even notice tx being "slower". So I agree there is a tragedy of commons effect but as long as the # of miners excluding all tx remains a minority it is unlikely to have any meaningful effect. |
|
|
|
|
I know bitcoind generates the "getwork" but does p2pool have any control over it. Say I wanted to only include paying transactions with a fee of >= 0.01 BTC in my blocks.
Does that require modifying p2pool to request modified work from bitcoind or simply modifying bitcoind to only include the matching transactions in the merkle tree?
|
|
|
|
I don't say that I'm right, I'm merely repeating the argument as I understand it. And I do find it convincing -- slavery has vanished all around the world; and only the USA needed a civil war to sort it out (and there were alternatives as mentioned above). To me, that's strong evidence that slavery inherently doesn't work.
Slavery "vanished" (although human trafficing, forced prostitution, sweatshops, forced labor camps, etc still exist) because it is a societal and humanitarian issue. You haven't proved that slavery isn't economical. It was very economical. If it wasn't then farmers in the south would have simply paid freeman and profited more. Are you saying plantation owners intentionally sacrificed their profits in order to keep slaves? Simpler analogy. Dinosaurs vanished too. It likely wasn't economics which caused them to vanish. At best your theory that economics ended slavery is unproven, at worst it is wrong. |
|
|
|
|
nobody bypassed that issue. The miner likely has 1.0 to 1.4 TH/s of hashing power. Nothing indicates he has bypassed the proof of work. If he has why stop at 1.4 TH/s "effective hashing power". Why not 10 TH/s and make 8x as much.
He is a big miner. It would be like saying Deepbit solved 3 blocks last hour so they must have broken SHA-256.
|
|
|
|
But then: The point in cryptographic tools (like hashing the block to verify) is that the verify is quick, the reverse (brute-force) painfully slow? It was fast. The block chain took over 1000 days to create. If you downloaded and verified it in a day it was ~1000x faster to verify than create. With things like ramdisk (or improved client which keep portion of chain in ram) and the improvements the developers made to 0.6 it likely is 10,000x faster under optimal conditions. |
|
|
|
It's not even clear that this miner would include transactions if the fees were higher. Right now he isn't including the transactions with fees. He's including zero transactions. No one knows the reason for this. There is a fixed cost (in terms of software, complexity, bugs, troubleshooting, etc), for including ANY transaction. The aggregate transaction fees are so beyond worthless (a few pennies per block) that it doesn't make any economical sense to include any transactions. Including only paying transactions doesn't improve that dynamic. Including only paying transactions may lead to more paying transactions but that is an unknown and indirect benefit. If transaction fees were higher then there may be interest. At a minimum the miner may need to consider it either now or in the future. Today he is pulling down ~$250 per block. However say difficulty rises, the reward falls, and there is a crash on the market. That might make a block only worth $100. Now $100 is great unless you have gotten use to months and months of $250 per block. While realistic transaction fees wouldn't bring him back to $250 maybe they boost it to $100 vs $105. If $5 enough? I am not sure but it might be. This miner has some cost. Even as a botnet (if he is a botnet) he has opportunity cost. Fees create an economic incentive to include transactions. No economic incentive exists now. Having a few fees with a token amount doesn't change that. The avg block has about 80 tx. Even at 0.02 BTC each that is 1.6 BTC. When block reward falls to 25 and extra 1.6 BTC is significant. If transaction volume increases 50% over the next year if avg fee was 0.02 BTC that would be ~ 10% less income by excluding fees. Is 10% enough to change his method of mining? Who knows but 0.3% certainly isn't. |
|
|
|
For my watercooled servers I am buying 1 more 5970 (and maybe buy a hot spare) and then I likely will only consider new 7970s or 7990s going forward. The bad news is for watercooling only dual GPU make any sense so I will need to wait. My pump and radiator has enough capacity for 2 more rigs of 5970s but honestly their age is starting to concern me. Now if the price drops to sub $300 that concern will go out the window. |
|
|
|
One of my friends asked me if I could sell him 1 to 3 Bitcoin each month, because he needed it for small purchases (like a VPN). I showed him that he could mine them with a Radeon he had, and make 3-4 Bitcoins each month. He's really happy of getting his 3-4 Bitcoins/month and he doesn't really need more than that. My point is that in time he won't be earning 3-4 BTC per month he will be getting 0.1 BTC per month "for free" and paying 20 BTC in electricity to get it. Either he will be forced to become a specialized miner and devote significant capital and other resources or he will start buying his coins. Lots of people buy Gold Coins, not that many people mine them. Even if you had gold under your house you likely couldn't extract it for less than market rates without specialized equipment and skill (or pay someone else to do it). My hypothesis is that over time the miners as a % of Bitcoin users will decline (from 100% prior to exchanges) down to 10% or so. The margins will be so small even for optimal miners (cool summers, low electrical cost, lots of space, capital for largest most efficient rigs, etc) that non-optimal miners will simply be mining at a loss. Then again maybe I am wrong. |
|
|
|
|
Miners will never be more than a small fraction of the Bitcoin population.
By protocol the reward if fixed. More miners simply means the reward is split into smaller and smaller chunks. The price/difficulty ratio is set by the lowest cost miners (in terms of uptime, electrical rates, size, skill, hardware, etc). If there is profit for the network to expand they will expand. When there isn't sufficient profit people like your Grandmother will be the ones forced out.
As time goes on Bitcoin mining will become a more and more specialized industry. Someday giant warehouses with rack and rack and racks of ASIC servers will hash full time being monitored by dedicated staff with profits going to owners or even shareholders.
|
|
|
|
|
They may or may not be able to do that legally however it will take a lawsuit to find out. So far any seizures they have done haven't been worth the effort for anyone to contest them. The fact that they are in Japan and most of their customers are not in Japan hasn't helped.
Eventually I would suspect they will be sued and if found in violation hopefully get slammed with some massive punitive damages on top of actual damages.
I can't see how even the most forced reading of KYC or AML laws requires them to track tainted coins and if they did what is "tainted"? Did Bitcoinica file a police report? If not then based on what due process are they even considering the coins stolen? Because an anonymous person (no offense Zou) on an anonymous message board said their anonymous funds were stolen.
Mt Gox. I had 783901237129037289312701389 coins stolen 9 seconds ago. I will send you some addresses please comply with "the law" and block all the tainted coinz and stuff.
Complying with the law is one thing, being the Bitcoin Police is another. Someday I expect a lawsuit but it likely won't happen until they fuck over the wrong person (someone with both the means and opportunity to strike back).
|
|
|
|
Newegg listing is obviously a misquote. http://www.tomshardware.com/reviews/geforce-gtx-680-review-benchmark,3161-4.htmlFirst, we launch a single run of the Central Park level at 1920x1080 in DirectX 11 mode, without anti-aliasing. We get a 72.3 FPS result, and we observe GPU Boost pushing the GeForce GTX 680 between 1071 and 1124 MHz during the run (up from the 1006 MHz base).
The top chart shows that we’re bouncing around the upper end of GK104’s power ceiling. So, we increase the target board power by 15%. The result is a small jump to 74.2 FPS, along with clocks that vacillate between 1145 and 1197 MHz.
Figuring the power target boost likely freed up some thermal headroom, we then increase the offset by 100 MHz, which enables even better performance—76.1 FPS. This time, however, we get a constant 1215 MHz. Nvidia says this is basically as fast as the card will go given our workload and the power limit.
So why not up the target power again? At 130% (basically, the interface’s 225 W specification), performance actually drops to 75.6 FPS, and the graph over time shows a constant 1202 MHz. We expected more performance, not less. What gives? This is where folks are going to find a problem with GPU Boost. Because outcome is dependent on factors continually being monitored, performance does change over time. As a GPU heats up, current leakage increases. And as that happens, variables like frequency and voltage are brought down to counter a vicious cycle.
The effect is similar to heat soak in an engine. If you’re on a dynamometer doing back to back pulls, you expect to see a drop in horsepower if you don’t wait long enough between runs. Similarly, it’s easy to get consistently-high numbers after a few minute-long benchmarks. But if you’re gaming for hours, GPU Boost cannot be as effective.
Our attempt to push a 200 MHz offset demonstrates that, even though this technology tries to keep you at the highest frequency under a given power ceiling, increasing both limits still makes it easy to exceed the board’s potential and seize up.
Sliding back a bit to a 150 MHz offset gives us stability, but performance isn’t any better than the 100 MHz setting. No doubt, it’ll take more tinkering to find the right overclock with GPU Boost in the mix and always on. |
|
|
|
|
This has been proposed many times the issue comes down to centralization and trust.
Say I start D&T Coin. 1 USD buys you 1 D&T coin. Lets ignore the risk of 51% attacks, etc.
I promise to buy D&T Coins back for 1 USD. I sell D&T Coins for 1 USD. If people have confidence it will exchange at roughly 1 USD per D&T Coin (minus friction costs).
You buy 1 D&T I put 1 USD in the bank. = good.
You buy 100,000 D&T coins I put 10,000 in the bank and buy myself a 90K sportscar = bad.
Worse I cheat on my taxes and IRS seizes the bank account holding the reserve of coins.
If you trust me (and you trust my employees, and my govt, and my security, and my bank) and I don't break that trust well everything is fine but if I break that trust you are screwed.
|
|
|
|
|
Show Posts
