Eventually at most only 21 million coins for 6.8 billion people in the world if it really gets huge. But don't worry, there are another 6 decimal places that aren't shown, for a total of 8 decimal places internally. It shows 1.00 but internally it's 1.00000000. If there's massive deflation in the future, the software could show more decimal places.

Completely non-reversible transactions are not really possible, since financial institutions cannot avoid mediating disputes. The cost of mediation increases transaction costs, limiting the minimum practical transaction size and cutting off the possibility for small casual transactions, and there is a broader cost in the loss of ability to make non-reversible payments for non-reversible services. With the possibility of reversal, the need for trust spreads.

The price of any commodity tends to gravitate toward the production cost. If the price is below cost, then production slows down. If the price is above cost, profit can be made by generating and selling more. At the same time, the increased production would increase the difficulty, pushing the cost of generating towards the price.

The result is a distributed system with no single point of failure. Users hold the crypto keys to their own money and transact directly with each other, with the help of the P2P network to check for double-spending.

The timing is strange, just as we are getting a rapid increase in 3rd party coverage after getting slashdotted. I hope there's not a big hurry to wrap the discussion and decide. How long does Wikipedia typically leave a question like that open for comment? It would help to condense the article and make it less promotional sounding as soon as possible. Just letting people know what it is, where it fits into the electronic money space, not trying to convince them that it's good. They probably want something that just generally identifies what it is, not tries to explain all about how it works.

Difficulty just increased by 4 times, so now your cost is US$0.02/BTC.

There would be many smaller zombie farms that are not big enough to overpower the network, and they could still make money by generating bitcoins. The smaller farms are then the "honest nodes". (I need a better term than "honest") The more smaller farms resort to generating bitcoins, the higher the bar gets to overpower the network, making larger farms also too small to overpower it so that they may as well generate bitcoins too. According to the "long tail" theory, the small, medium and merely large farms put together should add up to a lot more than the biggest zombie farm.

The average total coins generated across the network per day stays the same. Faster machines just get a larger share than slower machines. If everyone bought faster machines, they wouldn't get more coins than before.

I've developed a new open source P2P e-cash system called Bitcoin. It's completely decentralized, with no central server or trusted parties, because everything is based on crypto proof instead of trust. Give it a try, or take a look at the screenshots and design paper: Download Bitcoin v0.1 at

Bitcoin - Open source P2P money

Bitcoin is an innovative payment network and a new kind of money. Find all you need to know and get started with Bitcoin on bitcoin.org.

To implement a distributed timestamp server on a peer-to-peer basis, we will need to use a proof-of-work system similar to Adam Back's Hashcash, rather than newspaper or Usenet posts. The proof-of-work involves scanning for a value that when hashed, such as with SHA-256, the hash begins with a number of zero bits. The average work required is exponential in the number of zero bits required and can be verified by executing a single hash.

Total circulation will be 21,000,000 coins. It'll be distributed to network nodes when they make blocks, with the amount cut in half every 4 years. first 4 years: 10,500,000 coins next 4 years: 5,250,000 coins next 4 years: 2,625,000 coins next 4 years: 1,312,500 coins etc... When that runs out, the system can support transaction fees if needed. It's based on open market competition, and there will probably always be nodes willing to process transactions for free.

I've been working on a new electronic cash system that's fully peer-to-peer, with no trusted third party.

The attacker isn't adding blocks to the end. He has to go back and redo the block his transaction is in and all the blocks after it, as well as any new blocks the network keeps adding to the end while he's doing that. He's rewriting history. Once his branch is longer, it becomes the new valid one.

I don't know anything about any of the bug trackers. If we were to have one, we would have to make a thoroughly researched choice. We're managing pretty well just using the forum. I'm more likely to see bugs posted in the forum, and I think other users are much more likely to help resolve and ask follow up questions here than if they were in a bug tracker. A key step is other users helping resolve the simple stuff that's not really a bug but some misunderstanding or confusion. I keep a list of all unresolved bugs I've seen on the forum. In some cases, I'm still thinking about the best design for the fix. This isn't the kind of software where we can leave so many unresolved bugs that we need a tracker for them.

You can get coins by getting someone to send you some, or turn on Options->Generate Coins to run a node and generate blocks. I made the proof-of-work difficulty ridiculously easy to start with, so for a little while in the beginning a typical PC will be able to generate coins in just a few hours. It'll get a lot harder when competition makes the automatic adjustment drive up the difficulty. Generated coins must wait 120 blocks to mature before they can be spent.

Once the latest transaction in a coin is buried under enough blocks, the spent transactions before it can be discarded to save disk space. To facilitate this without breaking the block's hash, transactions are hashed in a Merkle Tree, with only the root included in the block's hash. Old blocks can then be compacted by stubbing off branches of the tree. The interior hashes do not need to be stored.

The proof-of-work is a Hashcash style SHA-256 collision finding. It's a memoryless process where you do millions of hashes a second, with a small chance of finding one each time. The 3 or 4 fastest nodes' dominance would only be proportional to their share of the total CPU power. Anyone's chance of finding a solution at any time is proportional to their CPU power.

The solution we propose begins with a timestamp server. A timestamp server works by taking a hash of a block of items to be timestamped and widely publishing the hash, such as in a newspaper or Usenet post. The timestamp proves that the data must have existed at the time, obviously, in order to get into the hash. Each timestamp includes the previous timestamp in its hash, forming a chain, with each additional timestamp reinforcing the ones before it.

The credential that establishes someone as real is the ability to supply CPU power.

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