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1481  Other / Beginners & Help / Re: getwork protocol work failure/success on: March 12, 2013, 12:05:52 AM
If that is the case, how does the server know not to ask another client to perform this work ? since that would be a waste.

There are multiple valid solutions for any piece of work.  Any hash at or above the specified difficulty.  So for a given unit of work, eventually someone else will also find a hash that meets the minimum difficulty requirement. 

But even that doesn't matter as the work to be performed changes with every new transaction or when work on a new block is started.   So a miner that solves a block but withholds publishing the solution harms the pool.   Over a period of time the pool can determine that a specific miner is doing this and give that miner the boot.

Even when that is discovered, it isn't worth going back and re-doing that work because since that time the work has changed (as now there are new transactions or new blocks or both).
1482  Other / Beginners & Help / Re: Hey guys, Just saying hi! on: March 11, 2013, 11:04:34 PM
But I was just told by BFL Support that they aren't released yet, and wont be until June?

BFL speculation is an olympic sport around here.

1483  Bitcoin / Bitcoin Discussion / Re: Miners: Demand more in fees from the userbase by blocking spam transactions on: March 11, 2013, 11:01:32 PM
My solution for the Satoshi Dice spam is here:
1) Pools or big solo miners remove all transactions from blocks they mine that don't have at least a 0.01 BTC fee attached to them
2) which don't have at least 0.01 BTC per each output.

So SatoshiDICE could respond by paying a miner which controls just 3% of all hashing strength to include all of SatoshiDICE transactions.  On average this operator with 3% of capacity will would get a block four times a day (once every six hours).  
1484  Bitcoin / Development & Technical Discussion / Re: New Exchange on: March 11, 2013, 10:31:53 PM
I'm interested in starting a new bitcoin exchange, and am currently looking for some potential partners with development experience.

Suggested reading:

So you think you're going to start a Bitcoin business, right?
1485  Economy / Service Discussion / Re: Okpay debit card - experiences on: March 11, 2013, 10:26:28 PM
i just stumbled across the Okpay debit card and for as far as i could see it looks promising. but i have a few questions about it.
- can you fill it up with bitcoins ?

It is a prepaid debit card, denominated in USDs.  You can "top up" your OKPay debit card using bitcoins as the source of funds (which they convert to USDs).

2.5% fee for a deposit/payment.


- do they need your personal data ?


- does it work just like a normal mastercard ?

Just like a normal prepaid debit card from Mastercard. 

What are the experiences in general with this card ?

I'm curious as well.
1486  Bitcoin / Technical Support / Re: Bitcoin-QT restore backup on: March 11, 2013, 10:15:57 PM
So i recently got back into bitcoins again, and on my current wallet I have a small amount already. But now I found back my old bitcoin backup where I had 2 BTC sitting for me. Now i've been searching around on how to restore bitcoins and all but I wonder if I need a complete newly installed Bitcoin-QT client to back it up, or can I use my current one with some cents on it to restore my 2 BTC to that? And if so, how?

So you have two wallet.dat files, one that use currently and an older one that should have 2 BTC on it?

There's no "merge" method, unless you manually export the keys from one and import them into another.

The easy way to resolve this is to just import the backup wallet.dat into a new and spend those funds to wherever you are running with the small amount today.
1487  Other / Beginners & Help / Re: I want to build a mining rig. on: March 11, 2013, 09:54:59 PM
well in my opinion depending how much you want to commit to bitcoin just stick with the 2 cards for now and wait untill we find out whats happening with the ASIC miners

I think we know what's happening with the ASIC miners.

If it weren't for the corresponding skyrocketing exchange rate as well, nobody would be talking about adding more GPUs.

Difficulty is going up at least 10% with this next adjustment then we get to see all of the Avalons kick in, and ASICMINER continuing its assault.

Unless there's a good place to use these GPUs after a few months, buying more GPUs today is probably not a good idea.
1488  Other / Beginners & Help / Re: Newbie is looking for the code of the mining process on: March 11, 2013, 09:48:19 PM
But I'd like to find the mining code - especially the main part where the block headers are hashed until a fitting hash is found which creates a new block.

Mining software comes from multiple sources.

Here's one that might help you see what it is doing though:

New pure-python CPU miner, for fun and testing
1489  Other / Beginners & Help / Re: splitting private key in two and giving it to two people on: March 11, 2013, 09:42:27 PM
Your thoughts?

Encrypted paper wallets. 

The encryption key goes to DeadMansSwitch and to some other trusted party.  If this is worth anything of significance you can pay an attorney to hold it and that attorney is bound by the attorney-client privilege to not share any of that information except as directed by you.

The paper wallets go to A and B.

Described here:

So the encrypted paper wallet(s) go to family members.  DeadMansSwitch gets the decryption key, as does the trustee.  From another thread:

I changed the colour to blue for encrypted paper wallets to provide distinction between encrypted/unencrypted paper wallets - a version in the original yellow is included in case you really like yellow, just delete 'note_encrypted.png' and rename 'note_yellow.png' in its place.

This solution (encrypted paper wallets) robably isn't ready for prime time, but give it a few weeks and that will probably become a very good method for offline / long term savings that is secure.
1490  Other / Beginners & Help / Re: Sorta new to this whole thing on: March 11, 2013, 09:23:12 PM
I was told to ask questions about bitcoining here (recommended from another forum), I am new to this whole process and I don't quite understand the whole process of bitcoin mining, other than it is a very slow process.

Does anyone have any links, I have read the wiki page on the main bitcoin page, but I still don't get it.

Short (and inaccurate) answer: Mining pools make available some computational work to be performed, mining operators perform that work and get paid.  Specialized hardware does this work much faster than general purpose computing hardware (e.g., A GPU is much faster at mining than a CPU on a desktop PC is.  An ASIC built for mining is much faster than a GPU.)    The decision to invest in mining hardware involves speculation of a handful of factors with significant unknowns.

Long, drawn out answer:

Mining is the process that records the history of all bitcoin transactions over time.  

When you withdraw money at an ATM, that machine first requests permission to withdraw N dollars from your account and after the transaction your bank ledger system subtracts that amount from your account.   Your bank is the authority over what transactions occur and what the history of your account looks like.   Their ledger is where that history is stored and is the master authority for each subsequent withdrawal request.   If there is an issue, you need to appeal to your bank to get it straightened out.

Bitcoin's value is in being decentralized.  There is no "master authority".  

So why would a merchant, say, ship out gold coins if I am paying in a form of money that has no physical form and which there is no authority?

So they must be able to trust that the transaction cannot be reversed under any circumstances.  

That's what miner's provide -- a way that a Coinabul can accept payment without concern about the payment being reversed.

So, how do miner's do this?

When a transaction is sent, it gets relayed to peer nodes (a typically number of peer nodes connected to might be Cool.   When a peer node first sees a transaction it first does a check to make sure the coins used to pay have no previously been spent.  Each node verifies the transactions and then further relays it to other peer nodes.  So within seconds nodes around the entire world have seen and verified a new transaction.  

Mining nodes are special nodes which are not just verifying the transactions but trying to construct a batch of them.  This batch is called a block.  Each block has a reference to the prior block.  They are chained together.  So by looking at all the blocks in the chain, the software can determine what coin transactions have not yet been spent.    Miners build blocks because they are rewarded financially for doing so.  Currently most of the reward comes from a subsidy paid for through issuance of the currency.  A smaller amount of the reward comes from the transaction fees that are paid.   With all of the miners combined it will take about ten minutes before one miner figures out a solution that is acceptable and the block is valid.  So today that reward is 25 BTC per block every ten minutes.  At nearly $50 per BTC, that's about $180K USD being paid to all the miners combined each and every day.

Because mining nodes learn of transactions at different times, not every miner is building the same history.  If a transaction arrives too late, or the miner ignores it for whatever reason, the contents of the block could be different from the block produced by another miner.   But there can only be one truth.  So let's say two miners, Bob and Alice, are both working on the next block, say block #100, and they both submit a block of transactions and the contents differ.   With a solution for block #100, miners start working on block #101.  Some of Bob's peer nodes who are mining will extend on his block #100 and not even know about Alice's block #100.  At the same time some of Alice's peers will start extending her block #100, unaware that other miners are already working on extending Bob's block #100.  So the mining work is splintered.  There needs to be a conflict resolution method so that either Bob's wins or Alice's wins.   If Alice's block ends up winning, Bob loses his reward.  And vice-versa.   How does Alice's win?   By having #101 extend off her #100 and not Bob's, then #102 must extend off the #101 she was party responsible for.  Then #103, and #104, #105, #106, etc.    Once a block has another five blocks that have extended off of it, there's essentially no chance remaining that she would lose that reward.  It isn't up to Alice though, it is up to other mining nodes to extend off of her block.  

Miners don't know each other, so it isn't like Fred who is a friend of Bob will choose Bob's #100 over Alice's.  Instead what happens is the miners extend off of whichever block they get first.  So if a miner knows of block #99, and now receives Alice's #100 that's the one that gets extended.  If a few seconds later Bob's block #100 shows up it doesn't matter.  The miner is already hard at work trying to build block #101 that extends off of Alice's #100.

That conflict resolution determines which is the truth -- either Alice's or Bob's will become truth.  Once a block has five more blocks that have extended off of it (so a total of six blocks including the one with the transaction) it becomes "truth" -- at least as far as a merchant like Coinabul is concerned.

So mining is the process of building consensus of the truth.

If all that makes any sense, then you probably have a dozen more questions about mining.  Like why did Alice and Bob submit a block #100 and not a thousand other people all at the same time.  Or if there is a reward that produces profit, more people will be attracted to mining -- won't blocks com faster and faster? etc.

For those, Satoshi's white paper is excellent.

Bitcoin: A Peer-to-Peer Electronic Cash System
1491  Economy / Goods / Re: Any long distance calling cards for sale for BTC? on: March 11, 2013, 08:01:40 PM
I have seen wireless cards for sale but not long distance cards.

NET10 sold here:

I'ld seen on some cards sold at one time but none currently.
1492  Economy / Marketplace / Re: What escrow systems do people use? on: March 11, 2013, 07:56:18 PM
is there an actual service, or do people simply use trusted forum members to handle exchanges?


Escrow list
1493  Bitcoin / Legal / Re: Legal deterrent to 51% attack on: March 11, 2013, 07:54:51 PM

I noticed this blog post that speculates that a 51% attacker could be prosecuted under fincen rules.  If that were true wouldn't that also mean that all miners would also be subject to the fincen rules (even though they don't have 51%)?

I think it is a moot point, essentially.

The reason a 51% attacker would do that attack is to either harm bitcoin (and thus has no intention of selling newly mined coins) or to gain economically by double spending transactions the attacker previously made (i.e., to where the attacker obtained value which was paid for prior to the attack, but then was able to double spend as part of the attack and thus defraud the seller who accepted bitcoin payment from the attacker.)
1494  Economy / Marketplace / Re: Selling to Europe on: March 11, 2013, 12:10:37 PM
Someone should open a warehouse in Europe dedicated to Bitcoin commerce.  In fact, there should be one in a major port city on every continent.

Fulfillment by Amazon, ships to 65 countries.

1495  Bitcoin / Project Development / Re: Bitcoin Price Image Generator on: March 11, 2013, 11:54:14 AM
I wanted a little weekend project and it seemed like there was a need for this!

There sure is!

Nice work.

This one is decent too:

1496  Other / Beginners & Help / Re: Best place to sell BTC in Europe? on: March 11, 2013, 11:51:44 AM
Where do you guys buy/sell for euros?

There are a few purchase and withdrawal methods

BITSTAMP,, and Mt. Gox. 

1497  Other / Beginners & Help / Re: Need help with sending BTC to myself on: March 11, 2013, 11:48:36 AM
I sent my coins from an independent site where I had a wallet, I checked the status on yet it says there has been no sorts of transactions on that address.

When using a hosted (shared) EWallet provider, your withdrawal is simply a request for the operator of that wallet to send the funds from their wallet.  If you aren't seeing it in the blockchain, the operator didn't send it.

If this was InstaWallet, they just had wallet/bitcoind issues recently hat should be resolved but if not check their thread for the latest as you may need to contact the operator directly.

1498  Other / Beginners & Help / Re: Invalid exchange? on: March 11, 2013, 11:21:13 AM
I've just opened up my very first wallet on Blockchain and deposited 50 bucks no problem a few days ago, but now when I tried to do it again it says Invalid exchange.  What does that even mean?  Huh Anyone else having a problem with this site? uses external partners for making it possible to buy bitcoins.

Was this the BitInstant/moneygram (U.S.) form, or UK form, or what currency?
1499  Other / Beginners & Help / Re: Do I contribute to the network just by running Bitcoin-Qt client? on: March 11, 2013, 11:18:40 AM
Conceptual question: Do I contribute to the bitcoin network just by running the Bitcoin-Qt v0.8 client?

If you accept incoming connections (e.g., firewall opened up to your IP) that might give other nodes an easier time of connecting.

A Tx is supposedly trusted after "6 confirmations". Who does the confirming? What constitutes a confirmation? Is it simply when 6 additional blocks have been added to the block-chain?[/quite]

Miners are the ones who include transactions into a block.    A confirmation is the name simply for the transaction making it into a block.  Blocks are chained together, so that first block plus the next five gives a chain of 6 blocks, each block is a confirmation so that gives you six confirmations.

When I first ran the client, I had to wait several hours for the block list to sync. Is it just that I got the block list from other clients,  and that's the "peer2peer" nature of the thing?

That's fast.  It used to take several days.

The full set of blocks since Satoshi's block #0 need to be downloaded.  That's what your client was doing.  Now that your is sync'd, it will share any blocks it knows about with any other peers that connect to you.
1500  Other / Beginners & Help / Re: Bitcoin CFD? on: March 11, 2013, 11:10:28 AM
is there any broker service out there to buy/sell BTC CFDs?

1Broker,com might.

BitFinex might. offers BTC/USD futures contracts that settle in bitcoins.

MPOE offers CALL and PUT options.


Don't discount counterparty risk.
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