Yup, that's really the simplest way to avoid the race attack.  Check the transaction on Blockchain.info.  If it shows there and doesn't show the flag of being a possible double spend, it is pretty safe to conclude it will eventually confirm.   There still is a tiny bit of risk though, including the Finney attack, so that's where you do risk assessment.  

A thief isn't going to mess with all this to try to get your $100 in a race attack.

And if you are trading a thousand dollars worth, it might be in your best interest to wait the ten minutes or so to get one confirmation.




There's no way to "cancel", but if you accept as payment on "0/unconfirmed" there is a risk that the payment will never confirm -- so it has the same effect as being "revoked".  Again, there have been no reports of anyone losing funds to this (MyBitcoin claimed losses due to double spending but never provided transaction IDs or other blockchain evidence to back their claim so it likely never happened.)

Yes. If you are on Wi-Fi and running the Bitcoin.org client, then the counterparty knows the IP address for your node.  If you are configured to allow incoming transactions, then the counterparty might have a pretty good attack vector if you have your node misconfigured for acting as a merchant.  

With proper preparation, the counterparty has a node specifically connect to yours.  Then at the time of the trade creates a payment to your address and broadcasts that transaction to your node only.  At the same time, or a fraction of a second earlier another transaction using those same coins for the payment to you is broadcast instead to well connected nodes and known miner nodes.    As a result, you may see the transaction at 0/unconfirmed and you would then think you have the funds.  But the miners will likely reject that transaction relayed by your node because a transaction they just had received had already spent the coins your node thinks it will be receiving.  

In that situation, the transaction you see will remain 0/unconfirmed, and the counterparty take the cash you handed over, never to be seen again.  

If the counterparty had bad luck and the transaction sent to you got relayed first to a miner that solves a block, that transaction would then eventually confirm but then it is just a normal trade -- you got coins and the counterparty got your cash.  When this happens then unless you were specifically monitoring the network looking for a double spend attempt, you wouldn't know that you were almost cheated. So there is little risk to a thief to keep doing this race attack until successful.

To prevent that, use the proper "merchant configuration" on your node -- which is to not allow incoming transactions (specifically -nolisten) and have it explicitly connect to a well-connected node.   There still is a small chance that you could be cheated though due to this race attack, and also a small chance of losing due to a Finney attack which the "merchant" configuration doesn't even protect you against.

Here's the double spending article on the Bitcoin wiki:

 - http://en.bitcoin.it/wiki/Double-spending

That being said, there have been no reports to-date of anyone losing funds due to an in-person trade where a double spend occurred.  It is much easier to operate a scam that defrauds the gullible than it is to execute a race attack that requires near perfect execution and a failure rate high enough that it will, over time, remain unprofitable.

There are many options for Buy coins and Send coins:

 - http://en.bitcoin.it/wiki/Mobile_Payment_Apps


Bitcoin Spinner (Android) has a Buy coins button but that just uses BitInstant.

CoinBase is probably going to be the closes to what you are looking for.  Think PayPal, with a linked bank account and where you can send a payment funded with a credit card, but uses bitcoins instead of USDs for the payment.   They are a young company yet though and those methods aren't even in testing yet.  It's coming.

In the meantime, combinations of services work pretty well.  A mobile app wallet (e.g., Blockchain for Android  + an exchange account) can be used together fairly easily.

Membergroups; or: Why do some users get colored coins under their names?

 - http://bitcointalk.org/index.php?topic=86580.0

The Bitcoin.org client will show you the transaction number for each transaction.  You can then check SatoshiDICE.com and see the status.

A photo from a mobile phone works too.

Ya, you might consider using Blockchain.info/wallet rather than trying to run Bitcoin from a system that has no persistent storage.

$100 worth of Bitcoin mining hardware has often returned BTC worth more than the $100 invested, even after subtracting the cost of electricity.

$100 worth of Bitcoin mining hardware rarely will return more than the number of BTCs that those $100 would have purchased.  Nearly all the gain has been the increase in the BTC/USD.  So let's go back to November 2011 when spending 1,000 BTC (worth $3,000 at the time) was a great idea, or so lots of miner's thought.  So today they've gotten back just 500 BTC from mining (now worth $6,000) and they still see it as having been an excellent investment.  This is because $6K is better than $3K, and they still have all the GPU hardware.

But those GPUs can mine for years and only bring in a few dozen more BTCs -- production will never reach the 1,000 BTC amount that they cost.

What is DF?


Installing Bitcoin won't harm an existing installation but it is always a good idea to make a backup before upgrading the software, for instance.


Just to make sure you aren't misunderstanding something ... your wallet doesn't have "an address" it has "many addresses".

Your wallet will hold many addresses, and you can still receive funds at a previously used address.

If you click the Addressbook, you will see your addresses.

Things I learned from a bit of Googling.  The source of income is in the U.S. and therefore the the US LLC or corporation would need to withhold 30% of the dividends and quarterly pay those withholdings to the IRS.  There could possibly be a similar withholding requirement for the state.   This is not a "maybe", but instead mandatory.    If the actual taxes due would be less, the foreign entity might want to file a tax return to get a partial refund of the withholding.

A country likes it when foreign sources of money arrive and are invested.  So the laws are just fine with an foreign entity having ownership in a U.S. corporation or LLC (as a rule of thumb ... there are certain protected industries and other specific restrictions on foreign ownership).

The challenge is finding a foreign jurisdiction that doesn't have prohibitive securities law.  One that doesn't care that a corporation or LLC is listed on unregulated exchanges in foreign jurisdictions.  I know Iceland had a virtual company provision on the drawing board.  That's about the closest thing I think.

Is this for a transaction you are receiving or for one that you sent?

Ok, try this.  Run Bitcoin-Qt with the -rescan paramater.





Well, it doesn't happen accidentally very easily.  In SatoshiDICE's instance, they have custom code that did that.  The Bitcoin.org client can possibly do that also if you are spending at the same time from the same copy of a wallet in two different places. 

So that's why even though this is a known problem, there aren't many reports of this problem occurring.  There is a fix ... you can perform wallet surgery using pywallet to remove ALL the transactions, and then rescan and it should be gone.  Just make sure you have made a backup of your wallet.dat first.

Sorry, I don't provide escrow service.

And for my view on this, you may have good intentions or you might not.  But the track record for anonymous operators is horrible and for the most part I keep my distance (and money) from them.  (BetsOfBitco.in is about the only one that I make an exception for)

Here's the latest example.  A new approach, with a very motivated individual:



And ... guess what?  Two weeks later:



So, sorry, but this just isn't something I wish to have any involvement in.

I think Open Transactions does everything you describe.

If that was a transaction sent to you, then perhaps it was a double spend.  If so, it will never confirm because the funds it was expecting to use have since been confirm in some other transaction.

To clear this transaction from your memory pool, you can simply close your client and restart it.

If this was from SatoshiDICE, here's the explanation:
 - http://bitcointalk.org/index.php?topic=77870.msg1191732#msg1191732

The getrawtransaction call, new in Bitcoin.org v0.7, should make collecting this type of info easier.

Also Armory has sample code (in extras) that should help make this job easier.

 - https://github.com/etotheipi/BitcoinArmory/tree/master/extras

Other options include libBitcoin, ABE, and more.

Staking a flag is associated with claiming of property as your own.

That's what a Mastercard would like to do, exclusive access to the market, with the backing by the State which keeps the Vodaphone/Orange or Safaricom (M-PESA) mobile payment types out as competition (or vice-versa, whatever the method, just the goal that some are allowed and favored by the State and others are excluded.)

Bitcoin doesn't need any government backing or support.    There isn't even a need to be exchanged into and out of the local currency through the banks ... because there are no banks:


 - http://blogs.the-american-interest.com/fukuyama/2012/09/06/what-myanmar-needs/

What is missing, however, is a decent SMS-based EWallet.    Coinapult could do this however they still are stuck at supporting the U.S. and Canada only.    Other mobile methods have SMS support, but the SMS is just notification and not the actual wallet like what Coinapult offers (where no web access is needed to set up and account nor to claim funds, etc.)

There are mobile payment systems that use voice-activated instruction instead of SMS.  That might be an alternative method to offer a mobile wallet for those with only feature phones  (either an additional method for transacting with an EWallet or as the sole method).

There is nobody working on building a voice-enabled bitcoin wallet as far as I know.  While the Burmese language is not widely used, there may not be many other geographic regions so ripe for a voice-enabled Bitcoin wallet to be introduced.

[Update:  Wow 1% internet penetration, and just 2% mobile penetration.   Even with feature phone capability it will be a long time before bitcoin could be used much here.  There could be bitcoin agents though who receive coins sent from abroad for remittance payments and pay out cash.]

Incidentally, they've change the name and the URL., ... no more hyphen in the name.


 - http://www.BitPay.com   or   http://BitPay.com

If not, there are numerous well-written alternatives:



You Can Learn Bitcoin 
 - https://www.coindl.com/page/item/391


or

Bitcoin  - The Libertarian Introduction
 - http://evoorhees.blogspot.com/2012/04/bitcoin-libertarian-introduction.html

or

Bitcoin: A Technical Introduction
 - http://vimeo.com/27177893



There might be some press and online media that explains it better than others:

 - http://bitcointalk.org/index.php?board=77.0  (2012)
 - https://en.bitcoin.it/wiki/Press  (2011 and prior)


A lot of people really enjoyed Linux Outlaws podcast (June 2011):
 - http://sixgun.org/linuxoutlaws-215/

or the Omega Tau podcast (March 2011):
 - http://omegataupodcast.net/2011/03/59-bitcoin-a-digital-decentralized-currency

When I am at a restaurant and see written on the menu the words CASH ONLY there is then no question as to how I will be paying for dinner. My only options are to leave without ordering, or to pay cash.

Now the restaurant owner knows that some customers prefer to pay with a credit card, but cash works better for the restaurant owner -- probably because of the credit card merchant processing fees of 3% or more.

Now if that is the only reason, the restaurant might wish to put up a sign "credit cards, add 5%", but in the U.S., in many states yet, that is prohibited by law.     So we as consumers are just used to letting the merchant raise prices to accommodate our preference for a convenient payment method.  (and those paying cash get stuck paying the higher prices even though they weren't responsible for any credit card fees.).

So Bitcoin adoption for consumer purchases will likely be led by merchants that wish to receive bitcoins over other payment methods.   When at the counter, you might get some perk when paying with Bitcoin versus paying with any other method.   Like, ... for your $40 tab, you can swipe your card and sign for $40 or you can pay $38.80 worth of bitcoins (a 3% discount).  Which would you choose?

Now, consider this.  Right now the fraud that credit card companies absorb is spread out over the massive amounts of legitimate purchases.  Now if consumers switch to cash methods (including PIN-based debit cards), then the fraudulent purchases that remain on credit cards starts eating up more and more of the profits for the card companies.   So they increase their merchant fees, which drives even more merchants away from accepting them, which causes the amount of fraud on a per-dollar basis to increase even more since that doesn't drop at all.    Credit cards just don't work well for quite a number of areas where payment card fraud occurs, including with online purchases.

Also, there are other merchants that are accepting bitcoin exclusively.  If you want Nestor's Unity board game then your payment choices are bitcoin, gold or silver.  That's it. ... no fiat currency whatsoever:
 - http://nestorgames.com/#unitydeluxe_detail


But that specific example is not going to be typical.  The 3% discount for paying with bitcoin certainly could become standard practice though.

Well, the block reward drop occurs at block 210,000 (when 10.5 million coins are issued, which is half of the 21 million total.)

So there's about 80 some days left (probably near the end of November):

 - http://www.BitcoinClock.com

As far as the exchange rate goiing up ...   this block reward subsidy drop wasn't unexpected.  The market tends to price in future events that it already knows about.