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I installed it on winXP and while running it, I was asked to update "something", dont remember exactly what it was.  After this update, BTC trader didnt start again! I uninstalled and reinstalled it, restart winXP, but BTC trader dont start. I only see for short time the "start window". What can I do? Thanks. Hi, realcoin! First, you can try to wipe all cached data which are usually stored at "C:\Users\<you>\AppData\Roaming\.btctrader\dev". And file me IDE log please if something goes wrong after wiping cache. |
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sending spam emails is certainly not going to make me sign up
Huh! Leaked MtGox database in action? |
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Does telnet service provide also historical quotes?
No. Live data only. In sierrachart feed I'm using bitcoincharts only for historical data (except using "-w" option to disable websocket), but delaying makes big problem - once bridge download historical data (delayed) and then start streaming quotes using websocket (realtime), there remain 15min gap without quotes in datafile, forever. And currently I'm thinking about some clean solution...
And here's a trick. I don't store live data into the datafile but aggregate and cache only historical data (that are delayed). Live data are sticked to the historical ones and are eventually replaced when historical data become available. Take a look to the source code. |
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Just rolled out automatic spike filter See britcoinGBP: | Before | After |  |  |
Get updated from BTC Trader: -> Help -> Check for Updates. |
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Do you mean BTC Trader does not have delayed data? Do you use different data source then?
Bitcoincharts has 2 channels of data, web api and telnet service. Only web data are delayed so I combine archive data with live ones. Just after starting the application there is 15-min data gap but it is filled after 15 min uptime. |
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1) OK, it is usefull to make ASIC less effective. But it is not enough. At least, they can use 20,000-40,000 GPUs to make the 51% attack. We need one more solution for this case.
Modern GPUs are memory-limited too. My HD6990 has >3000 cores and only 4GB RAM. This is ~1M per core. And this is only a good starting point for further thoughts. Also I mentioned earlier: if Bitcoin ever reach popularity comparable to Bittorrent that 51% attack should take much more GPUs, especially when POW is memory-bounded. But there is one more issue. Favoring GPUs or any other highly-specialized solution for minig doesn't encourage wider Bitcoin popularization. We should keep the doors open for newcomers. And in average they don't have top-level GPUs. 2) What new POW do you suggest? Your scheme with N=32M/32=1M ? IMHO, it is not good because calculation of 2^20 sha256 is too time-consuming. Each node (not only miners) needs to calculate POW each time when recieves a new block. Do you have another one idea? We can remember results of intermediate steps 0,8,16,24,32,40,48,63 of sha256 calculation, for example. It is 8 times more information,
but 2^17 calculations of sha256 is very time-consuming too.
2^20 sha256 computations over 32-byte vectors is equal to 1 sha256 computation over 32M file. It takes less than a second on my box. So I considering this to be acceptable. Moreover I don't insist on hashing something million times. That was only an example. Digging a little I've found interesting paper: Exponential Memory-Bound Functions for Proof of Work Protocols. Scheme that described in the paper is also two-dimensional (by memory amount and successive POW criteria). And I don't have any idea how to adjust memory requirements and "leading-zeros count" together with difficulty. Yes, if we will make "net of trust", then an attacker with more then 50% of computational power can create "alternative reality" in bitcoin, i mean alternative block chain, that will begin with the same generic block but then diverses with the "real" block chain. In fact, in this case can exist more then two block chains. And for a node that connects to the net, there will be impossible understand wich of them to connect and belief. IMHO, this problem can be solved only by out-of-bitcoin methods. All sites that work with bitcoin may\have to publish in what reality\block chain they work. I belief that they can detect which block chain is real. And usual users will check from time to time that they live in the same reality. It is not excellent, but I don't see any better solution. At least, by this approach it is possible to eliminate other problems of 50%+ attack:
Reverse transactions that the atacker sends while he's in control
Prevent some or all transactions from gaining any confirmations
Prevent some or all other generators from getting any generations
That would be something like Reeple, not like Bitcoin. |
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Ha-ha!  bitcoincharts.com is also delays its data for 15 min I have to do some tweaks in BTC Trader to handle this correctly. |
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I worked for 5 years for a company that creates ASIC chips, and I understand the process well enough. My estimation is that it is possible to create such an ASIC that will feed the same power as Radeon 5870 (for example), and calculate 20-100 times more hashes. It is not surprising because the chip is special-purpose, and GPU is universal. I suppose that it is possible to create such an ASIC in 6-12 months. The power of network now is approximately 12 Thash, that is equivalent to ~ 20000-40000 GPUs. That means that 2000 such chips would be enough to attain more than 50% of the computing power. I think, the cost of creating such a number of chips is approximately 5 million dollars. Indeed, the major part of this money would be spent on designing the chip, not on manufacture. Therefore, to create 10,000 chips like this, one would need approximately 10 million dollars. And 10,000 chips is 80% of the nets computing power.
So, I think that ASIC is the most possible way to accomplish 51% attack.
Agree. What can we invent to prevent net destruction? I have thought about it but I have not found any decision. IMHO, change POW method is useful only for the first time, because we can change our miners quickly, but it is not possible to change an ASIC chip. They would need to make another one (+3-6 months). Adding memory requirements in POW method is good idea, but it changes not much. Let us say, not 10 but 20 million dollars per 80% of the nets computing power.
Not agree. Idea isn't in just adding memory requirements to the POW but making the POW seriously memory-constrained. Say 1 POW needs 1 million sequential computations and 32M of RAM at a whole for each computation and that 32M can't be shared between POWs because there are different data. So the only way to implement such POW in ASIC is to add 32M of RAM to the chip wasting its area and dramatically increasing its cost and reducing its efficiency. And you can't make 32M of on-ASIC RAM cheaper than 32M of DDR module RAM. I think the better way to find the decision is to think about changing a way of cooperation of nodes. For example it is possible to create a system of trust between nodes. If one node makes some suspicious actions (destributes a new block that not contains a majority part of transactions or new block chain that removes the last 10 blocks), its "rank" decreases. If a node destribute good information, its "rank" increased. Information from nodes with too low "rank" is skipped. Its only a raw idea, I know. I just want to show the direction of how else it could be.
Bad idea. No one can prevent me from making millions of nodes each of which trusts to each other. Newly connected nodes have to trust my malicious sub-network with high probability only because of its size. If you propose to dedicate one bootstrap node and make it trusted by default (hard-coding certificate into client for example) you just invent PKI in its traditional form and that trusted-by-default node would become a central authority and would perform central-bank like functions. That's not we're all want to happen with Bitcoin. Anyway, what we can do just now (except finding decision) is to recognize the problem. And change in wiki the status of this vulnerability from "Probably not a problem" to "Might be a problem".
You damn right. It's "Might be a problem". |
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Personally though, I think the biggest threat is actually botnets, so the dominance of GPUs is actually preferable to me. For now it's true. But if you look to the BitTorrent network size you'll see more than 100 million peers. I think if Bitcoin would ever reach such popularity botnets shouldn't be a problem. |
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My suggestion was to have two chains verifying all transactions.
The one we have today + another with a different hashing algorithm which favors generic cpus. That's a problem. Is there any existing well-known hashing algorithm which favors generic CPUs and have some properties preventing it to be implemented in highly-effective GPU/FPGA/ASIC for acceptable cost? |
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I not sure why, buy my graphic card's cooler getting mad, when I'm starting this software. Same I had when tried to generate btc.
What? There's a built-in miner? That would be a first, I think. Way to make "free software"  I doubt it, though, has anyone checked? That was in v1.4.1.1 because of infinite repainting bug. Now it's fixed by commit 6d5fcc34. There is no neither built-in miner nor any other type of malicious features. |
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A Radeon 6990 has 4 gigabytes of ram.
If the task is "find a number that bcrypts/scrypts to less than a given hash target," I don't see anything that would stop a GPU programmer from implementing bcrypt/scrypt on the CPU and parallelizing at the try-different-nonces level.
Maybe I'm missing something; I'm probably biased because I worked at SGI from 1988 to 1996 and saw first-hand the evolution of GPUs from very-special-purpose chips with very limited memory to very-general-purpose vector-processing pipelines with very fast access to lots of memory. HD6990 has more than 3000 processing units so bcrypt/scrypt/whatevercrypt can be relatively easy parallelized. My idea is to make each processing unit requiring a lot of RAM for intermediate data thus adding "GByte" dimension to "GHash" race and then keeping GByte-GHash profile similar to that one of the general-purpose PCs somehow. |
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From RedditI've read about many units of supercomputer, but not being an expert I couldn't relate to it. If someone wanted to do a 51% attack on the whole bitcoin network, effectively rewriting it's whole credit history, what kind of computing power would be needed? Does a company like Google or IBM, or some military installation has enough computer power at it's disposal to overwrite the current blocks? Is it possible? Lets do a trivial research: - Current network hashrate is 15 TH/s
- My $600 Radeon HD6990 performance is 700 MH/s
- Successful 51% attack should involve 21'500 such GPUs
- Cost of the attack is about 13 million dollars
As mentioned in the discussion... There's a very distinct difference between needing more computing power than the world's supercomputers combined and needing around 4-13 million dollar in equipment. Anything in that magnitude is very cheap not only for a government, but for most banks and big corporations - heck it's atainable even for a very rich individual. Honestly I don't see why what would be the motivation, but it's technically a fragile system.. Sad but true... The cause of such weakness is in the chosen POW method: sha256(sha256(H)). It allows building highly specialized, cost and power efficient mining rigs so shifting the balance from ordinary users having only their general-purpose PCs to governments and corporations with their resources for R&D in mining. How can we fix this issue? I propose a main criteria of specializability of POW method - the order of magnitude of the number of processing and storage elements necessary for 1 unit of rig. In case of sha256(sha256(H)) it's 10 ALUs + 8 RAMs per round and it's relatively simple to trade off processing power to storage and vice versa (I mean pipelining technique) because of high data locality. But we must keep the criteria as close to the general-purpose PC as possible yielding extensive techniques of specialization to be limited by exponential growth of the cost of such optimization. I haven't any idea better then increasing storage requirements for rig unit thus breaking the data locality. Say we have N storage units <S> where - S0=sha256(H);
- Si+1=sha256(Si+Sj), i=1..N, j=Si mod i;
- And finally POW=sha256(SN).
We need N to be big enough to outfit processor registers and cache with intermediate <Si> values and small enough to store whole that data at RAM without swapping. And also N need to be adjusted to the difficulty somehow. Any thoughts? |
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There are arbitrage robots |
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This is a crosspost from Trading Discussion forum thread. My name is Coinfreak and I proudly present: BTC Trader - opensource crossplatform live charting and technical analysis desktop application.  Current version 1.4.2 includes - Live data feed from bitcoincharts.com
- Daily data feed from Yahoo Finance
- Rich collection of tech-analysis tools
- Facebook and Twitter integration
- Automatic updates
- A lot of bugfixes since v1.4.1.1
Bundles for Windows, Linux and Max OS X are available. In order to update to v1.4.2 you have to completely uninstall v1.4.1.1 because of Automatic Updater was broken in previous version.This project is at beta-stage now. Bug reports and code contributions are welcomed! |
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This is a crosspost from Trading Discussion forum thread. My name is Coinfreak and I proudly present: BTC Trader - opensource crossplatform live charting and technical analysis desktop application. Current version 1.4.2 includes - Live data feed from bitcoincharts.com
- Daily data feed from Yahoo Finance
- Rich collection of tech-analysis tools
- Facebook and Twitter integration
- Automatic updates
- A lot of bugfixes since v1.4.1.1
Bundles for Windows, Linux and Max OS X are available. In order to update to v1.4.2 you have to completely uninstall v1.4.1.1 because of Automatic Updater was broken in previous version.This project is at beta-stage now. Bug reports and code contributions are welcomed! |
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This is a crosspost from Trading Discussion forum thread. My name is Coinfreak and I proudly present: BTC Trader - opensource crossplatform live charting and technical analysis desktop application. Current version 1.4.2 includes - Live data feed from bitcoincharts.com
- Daily data feed from Yahoo Finance
- Rich collection of tech-analysis tools
- Facebook and Twitter integration
- Automatic updates
- A lot of bugfixes since v1.4.1.1
Bundles for Windows, Linux and Max OS X are available. In order to update to v1.4.2 you have to completely uninstall v1.4.1.1 because of Automatic Updater was broken in previous version.This project is at beta-stage now. Bug reports and code contributions are welcomed! |
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Hot new BTC Trader v1.4.2 is available! 
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