"We define an electronic coin as a chain of digital signatures." There is a helpful diagram in the paper explaining the concept. If Alice has a coin and wants to give it to Bob, she takes the transaction in which she received the coin, adds Bob's public key to it, and digitally signs it to create a new transaction. Then if Bob wants to give it to Charlie, he takes this new transaction and adds Charlie's public key to it and signs it. And so on. That's what it means to create a chain of digital signatures. Anyone can prove that Charlie is now the legitimate owner of the coin because they can verify (with Bob's public key) that Bob signed it over to Charlie. And we know that Bob was the legitimate owner before Charlie because Alice signed it over to Bob. (How the very first owner got the coin is addressed later in the paper.)

SHA-256. All hashing in Bitcoin is SHA-256 (except for addresses, which use RIPEMD-160 as well).

Because the chances of two valid blocks having the same hash are so astronomical that anyone who suggests it's anything less than impossible will be laughed at. If you have a hash, and you have a block with the same hash, you can bet your life that that is the block the hash refers to.

No. You were right the first time:

I was just thinking of that. A standard Monopoly set originally contained $15,140, but that was increased in 2008 to $20,580. At that time, about 250 million sets had been sold, and since then about 3 million were sold per year. So the Monopoly money supply in 2008 was $3.785 trillion, increasing by about $62 billion per year, for an annual inflation rate of 1.6%. Since a Monopoly set costs about $15, one US dollar currently buys 1,372 Monopoly dollars. Assuming an inflation rate of 9.6% for the US dollar (based on increasing gold prices since Nixon abolished the gold standard because the CPI is useless) and that Hasbro keeps printing money at its current rate, the Monopoly dollar will achieve parity with the US dollar in just under 100 years.

One capable of displaying Tonal digits, such as this font. Blame Luke-Jr for this.

Such as those who grew up in the days before AdBlock and trained themselves to subconsciously ignore colourful flashing banners?

Not to put too fine a point on it, but no, you can't. You claim that the current system is bad and that your alternative is better, yet you don't actually have the faintest idea how the system works, what requirements it must meet, or even how to implement your alternative. You'll get no support from anyone until you take the time to understand what Bitcoin is and how it works and what technical problems it needs to address, and can explain in detail exactly how your alternative is supposed to work.

3 oz AU

You're looking at a brand new wallet, not your old one. Two possibilities: you didn't copy the old one into the correct directory, and/or you copied the wrong wallet entirely. Remember, each user account gets their own wallet, so if you logged into your virtual machine as a different user to the user who mined the coins (eg, Administrator when you weren't logged on as Administrator when you were mining), you'll be looking at an empty wallet. What operating system(s) are you using?

FTFY. You can have as many connect= lines as you need. Adding connect=127.0.0.1 should do the trick.

Unless you really think we're going to see negative prices by 2015, stop drawing straight lines on a linear chart.

It becomes instantly useful again the moment the attack ceases.

That would require a lot more than 51% to do in any reasonable timeframe. For example, to rewrite 1 year of transaction history within 1 year would require 67% of the hashing power. That's a whole year of continuous mining with double the hashing power of the rest of the network before you can even begin your attack. And that's assuming no checkpoints. With checkpoints, such an attack is completely and utterly impossible.

The attack will stop if legitimate miners can upgrade their equipment faster than the government does (which the government has to constantly pay for). Also, I didn't know the government got free electricity.

Double spends can't be fixed by reverting to a back-up blockchain, but apart from that (which is probably not a major problem anyway, since nobody will trust any transactions that occur during the attack), nothing will need fixing anyway. As disruptive as a 51% attack would be, the disruption is only temporary (though even a temporary disruption might still be economically disastrous).

You've got some more reading to do.

The 51% attack cannot "collapse the whole system", and in fact attackers are very limited in what kinds of damage they can do. They can only fraudulently reverse or modify their own transactions, not anyone else's. They can (temporarily) prevent other people's transactions from being confirmed, but not modify them in any way or reverse transactions which were already confirmed before the attack. They cannot steal other people's coins (except for sending his own coins and taking them back), and cannot create coins out of thin air. Such an attack would also be extremely obvious and users would be warned not to perform any transactions until it is clear the attack has stopped.

Also, the attackers can only do anything during the time they are actively mining with 51% of the hashing power. As soon as they stop mining, or if legitimate miners summon enough resources to regain the majority of the mining power, the network will resume normal operation, all transactions which the attacker blocked would soon start being confirmed, and it'll be almost as though nothing had ever happened.

That's not to say such the 51% attack is nothing to worry about. It would cause a total (but temporary) disruption of all Bitcoin services and probably a loss of faith in the currency resulting in a massive price crash, and it may take a long time to recover, but it's not the end of the world either.

Depending on your graphics card (the CPU is useless for mining), you might make a penny or two per day, minus the increased electricity cost of constantly running your computer at full load. Unless you have very cheap electricity, you'll be making a net loss.

Probably, unless you're willing to spend some money on more specialised mining equipment (FPGAs or ASICs).

Don't know, sorry.

If you're talking about a paper backup of your wallet, allowing anyone else to see it compromises the whole wallet. If you're talking about PrintCoins or Casascius coins and other such things intended to be circulated as cash, then only the address is "compromised", but you want it to be compromised: the idea is that people who receive such bills and coins can use the private key to transfer the bitcoins to their (digital) wallet, after which the bill/coin is worthless and is taken out of circulation.

The blockchain will have fewer transactions, as people conduct some transactions offline, but the bitcoins won't stay offline forever (see above). You might as well ask, "Will people withdrawing cash from their bank accounts ultimately ruin banks?", to which the answer is no, because the cash almost always gets deposited again at some point. Note also that lost or destroyed bitcoins are not a problem, as this simply has the result of increasing the value of all remaining bitcoins (slightly decreased supply + same demand), and bitcoins can be divided to 8 decimal places. Even if so many bitcoins were lost that only a tiny fraction of a bitcoin remained, the economy would still function just fine on that fraction of a bitcoin.

Which is exactly why it is worth less. For a central bank, "prudent action" and "making money" are mutually exclusive.

That's page 7, not page 9.

You remember incorrectly. Only the option in the GUI was removed, due to its uselessness. The miner is still present, presumably for the sake of being a complete implementation of everything needed to run the Bitcoin network, and can be invoked by starting Bitcoin-Qt or bitcoind with the gen option (either as a command line argument or in the configuration file), or with the RPC command setgenerate true (and setgenerate false stops mining, of course).

Yes, but it only uses your CPU, not your graphics card, and is therefore completely useless (which is why the option was removed from the GUI). It will take you many years or even decades to find a block this way, if ever. If you actually hope to ever make even a small amount of bitcoins, download a real miner such as cgminer and join a pool.

He's talking about Bitcoin-Qt's rarely-used (and for good reason) built-in miner. Running as a server is not required when mining this way, though it is an astoundingly bad idea.

What's the difference? How is buying and selling dollars fundamentally different from buying and selling anything else? Moreover, if nobody traded bitcoins for dollars, where would new users (which is what the community really needs) obtain them in the first place?

Miners receive the transaction fees in additional to newly mined bitcoins. This is to ensure that mining (which is necessary for the security of the network) will still continue even after all 21 million bitcoins have been mined, with mining then being supported entirely by transaction fees.

Yes, anyone can mine, though powerful hardware is required if you expect to make a decent amount, and you have to consider your electricity costs as well. Mining is not a get-rich-quick scheme, and in fact you are likely to make a net loss unless you have very cheap electricity or specialised mining hardware.