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3541  Economy / Trading Discussion / Re: Localbitcoins.com -- unusual request to sell -- Paranoid or Legit? on: July 20, 2013, 01:48:28 AM
If you don't feel comfortable about a transaction it is best to back out. It is your money and possibly even your life that is at risk. No one else can tell you what that's worth.
3542  Bitcoin / Electrum / Re: Why is there no "new wallet" function? on: July 19, 2013, 06:28:46 AM
Just run it via the command line:

electrum -w mynewwallet

Then make a shortcut with the above command in it for easy access.

Sure, there are a lot of workarounds, but I think this should be part of the GUI.

Yes we'd all like our choice of features to be part of the GUI. But it is a lot of work to support multiple wallets. Just look at a screenshot of armory and compare it to how electrum looks. The whole user interface will have to be overhauled. And would it be worth the effort? Most people are fine with one wallet. They would not like a cluttered UI that would only benefit a small percentage of users. People like you and me that want multiple wallets can use the command line.
3543  Bitcoin / Bitcoin Technical Support / Re: how to use paper wallet? on: July 18, 2013, 11:33:28 PM
bitaddress.org for bitcoin paper wallets.

And to import a private key you can just use the bitcoin-QT menus. There is an option for importing private key there.
3544  Other / Beginners & Help / Re: Broadcast Double Spend Transactions on: July 17, 2013, 09:53:18 AM
namecheap has become the first merchant to accept bitcoin payments without waiting for confirmations.

How about EVR bar?  Cups & Cakes Bakery?   Room 77 and the rest at Bitcoin Kiez?     The Pao Cafe?    Green Ave Market?   

All these are bricks & mortar businesses that don't wait for confirmation.

None have reported any double spending having occurred.

As you can see from my sig I live in Asia so I've never heard of these businesses before. I thought namecheap was the first in this regard.


Quote
I'd like to know what you think of the recent namecheap move? Do you think other merchants will follow suit?

A merchant category that would have the highest risk of loss from accepting payment on 0/unconfirmed would be the quarter machine at an unattended laundromat.    In that instance, there is little (or no) profit from each sale, and thus any losses due to double spend translate directly into losses to the merchant.   If the attacker has to try twenty-five times before finally succeeding at a double spend attempt with try #26, the attack is profitable to the attacker -- the attacker has both the loot and the bitcoins that were double spent.  Since the merchant won't know about the double spend until after the attacker has left (at the soonest), it can be presumed the chance of the attacker getting caught is nil.

We don't have these machines where I live but I assume by the name that only small sums are involved? Would a thief go through all that trouble for a few dollars?

Quote
Namecheap is a merchant that is on the other end of the spectrum.  Namecheap registers domain names, provides web hosting, etc.   If an attacker is successful at a double spend, as soon as Namecheap learns of the double spend  they have at their disposal their full control of the domain and any hosting services they provide.  So at most an attacker would get hours (or maybe a day) of domain registration or hosting and then lose access to the domain.  Thus there's absolutely no benefit from attempting to double spend against a merchant like Namecheap.

Actually one of the problems that hosts face is that people sign up, start spamming  or otherwise abusing their services and then chargeback. With bitcoin it would be a double spend instead of a chargeback. You can spam quite a bit even within a few hours and the host is left to clean up the mess. So there is always a risk.
3545  Other / Beginners & Help / Re: Broadcast Double Spend Transactions on: July 17, 2013, 04:51:42 AM
If the retailer can make it economically unprofitable to try to double spend then there won't be a problem.  i.e., if the attacker/thief has to buy 19 hamburgers before the 20th is "free" from a successful double spend, then an attacker probably isn't going to try.  But the merchant isn't looking to figure out a way bitcoin will work, the merchant is looking only to sell hamburgers, and if a payment network gives hassle and risk it is not likely to be embraced.

Sorry to bump up this thread but I think it is relevant given that namecheap has become the first merchant to accept bitcoin payments without waiting for confirmations. So looks like Stephen was at least half right above.

Stephen, if you are still subscribed to this thread I'd like to know what you think of the recent namecheap move? Do you think other merchants will follow suit?
3546  Bitcoin / Electrum / Re: Why is there no "new wallet" function? on: July 16, 2013, 01:24:50 AM
Just run it via the command line:

electrum -w mynewwallet

Then make a shortcut with the above command in it for easy access.
3547  Economy / Service Discussion / Re: Help understanding payment verification via blockchain.info JSON API on: July 14, 2013, 06:20:24 PM
Another thing is that there is a question mark on the accuracy of blockchain.info's output when using getreceivedbyaddress. Blockexplorer is correct in this instance:

18+ http://blockexplorer.com/q/getreceivedbyaddress/1H9uAP3x439YvQDoKNGgSYCg3FmrYRzpD2

15+ http://blockchain.info/q/getreceivedbyaddress/1H9uAP3x439YvQDoKNGgSYCg3FmrYRzpD2

I created the following script and it outputs the blockexplorer number both times even when using blockchain.info data:

Code:
<?php
$target_address 
'1H9uAP3x439YvQDoKNGgSYCg3FmrYRzpD2';
$tx json_decodefile_get_contents"http://blockchain.info/address/$target_address?format=json" ), true );

//print_r( $tx );
$sum 0;
foreach( 
$tx'txs' ] as $transaction ) {
foreach( $transaction'out' ] as $output ) {
if( $output'addr' ] == $target_address ) {
//echo $output[ 'value' ]/100000000 . "\n";
$sum += $output'value' ];
}
}
}

echo 
"blockchain.info sum of received: " $sum/100000000;

$bec json_decodefile_get_contents"http://blockexplorer.com/q/mytransactions/$target_address"), true );

//print_r( $bec );
$bec_sum 0;
foreach( 
$bec as $transaction ) {
foreach( $transaction'out' ] as $output ) {
if( $output'address' ] == $target_address ) {
$bec_sum += $output'value' ];
}
}
}

echo 
"\n" "Blockexplorer.com received sum: $bec_sum";
3548  Economy / Service Discussion / Re: Help understanding payment verification via blockchain.info JSON API on: July 14, 2013, 05:42:14 PM
I looked into this a little more and you might be better off using getreceivedbyaddress:

https://blockchain.info/q
http://blockexplorer.com/q

You can see an implementation of this in the function BWWC__getreceivedbyaddress_info in bwwc-utils.php of this WP plugin:

http://wordpress.org/plugins/bitcoin-payments-for-woocommerce/
3549  Economy / Service Discussion / Re: Help understanding payment verification via blockchain.info JSON API on: July 14, 2013, 05:23:50 PM

I am going to issue a unique payment address to all sales and get the total received to enter into my DB/ecommerce system, but what if someone then pays on the same unique address. is there a better way that i can get the amount actually received rather than the total received? (as if some one can break things, i find they usually will)

Any help at all or advice would be great (and if anyone finds this code or thread useful, great feel free to use it)

Best Regards
Ford

First up I had no idea you could query blockchain.info data in json format like that. So thanks for that.

Second the solution to your problem is to use a separate address for each transaction. This is actually the recommended way to do things. It will help you to track individual transactions and assign credit to different customers.
3550  Bitcoin / Bitcoin Technical Support / Re: Created a new address in bitcoin-qt, and it already contains 0,001 BTC ??? on: July 12, 2013, 06:37:27 PM

Even with trillions of addresses, there would still be no collision. 2^256 is a very big number, almost as all the atoms in the visible universe.

It's a big number but not as big as you said. 2^256 is 0.12% of the atoms in the visible universe:

click

Of course a collision is highly unlikely.

It's just as big as I said. I never said it was bigger than every atom in the observable universe. I was saying stars. Which is already a pretty big number, atoms of course is even bigger.

I wasn't replying to you.
3551  Bitcoin / Bitcoin Technical Support / Re: Created a new address in bitcoin-qt, and it already contains 0,001 BTC ??? on: July 12, 2013, 06:28:28 PM

Even with trillions of addresses, there would still be no collision. 2^256 is a very big number, almost as all the atoms in the visible universe.

It's a big number but not as big as you said. 2^256 is 0.12% of the atoms in the visible universe:

click

Of course a collision is highly unlikely.
3552  Bitcoin / Bitcoin Discussion / Re: POLL: How much blockchain data is filling your hard drives? on: July 11, 2013, 03:37:15 PM
Switched to electrum so no blockchain locally for me. It wasn't practical running bitcoin-qt on a 1Mbps connection anyway.
3553  Other / Off-topic / Re: Name some good stratergy games on: July 10, 2013, 08:26:07 PM
Rise of nations. Old but very good.
3554  Economy / Service Discussion / Re: If you used Brainwallet.org - MUST READ! - Security Breach! on: July 06, 2013, 10:56:31 AM
Sounds like a weak passphrase to me.  We already know that people have created huge 'rainbow tables' of bitcoin addresses generated from SHA256 of weak passphrases, and they just sit watching the blockchain for any of them to come up and then siphon off the funds.  This is yet another reason why a 'brain wallet' is such a terribly bad idea for anyone to do.

Will

A brain wallet when done right is perfectly fine. A deterministic wallet like electrum is like a brain wallet. 12 words that are the seed to all your bitcoin keys. Of course the entropy is greater than your typical brain wallet. 128 bits for electrum.
3555  Bitcoin / Bitcoin Technical Support / Re: Securely watching for transactions on large numbers of addresses. on: July 05, 2013, 04:09:15 PM
There is a plugin for wordpress that does this:

http://terk.co/wordpress-bitcoin-tips-plugin/

It uses a free service by blockchain.info. Basically blockchain.info generates a unique address each time you call it and it forwards all bitcoins sent to that address to an address you specify. It also callbacks your script each time someone sends bitcoins so you can keep track of transactions:

http://blockchain.info/api/api_receive
3556  Bitcoin / Bitcoin Technical Support / Re: Corrupt Wallet?? on: July 04, 2013, 10:20:20 AM
It could be a problem with your hard disk. You should check it for bad sectors.

Other possibilities are malware. So a virus scan would be a good idea.

2) Maybe.

3) Yes.

4) Maybe.

If you are worried about this sort of thing I recommend using electrum. You only have to back it up once and the backup is just 12 words that you remember/write down.
3557  Bitcoin / Bitcoin Technical Support / Re: blockchain wallet backup on: July 04, 2013, 10:17:29 AM
Use the email backup option. It will send you an encrypted copy of your wallet. Just save the attachment of that email. Keep in mind that if you create new addresses or send coins using your wallet you will need to create a new backup too. Otherwise you risk loosing coins.

If you are looking for a good desktop wallet client I recommend electrum. It does not require you to download the blockchain and it is deterministic which means that backing it up is as easy as remembering 12 words (you can write them down and store them somewhere safe). You only have to do this once with electrum regardless of the number of transactions you do.
3558  Bitcoin / Bitcoin Technical Support / Re: Minimum spec vps to support bitcoind? on: July 01, 2013, 02:06:07 AM
I had swap on my openvz vps. 256mb of vswap + 768mb dedicated RAM. Yet it wasn't enough. But I was using 0.8.2. I hear there are some bug fixes for memory problems in 0.8.3. So maybe less RAM will do for the newer version.
3559  Local / Other languages/locations / Re: Pakistan on: June 27, 2013, 04:17:52 PM
Welcome bro.
3560  Local / India / Re: Blockchain.info - WatchOnly address scam on: June 27, 2013, 06:05:41 AM
If people only took the time to learn the basics of bitcoin they would never be fooled by this scam. I mean you don't even have to know about how blockchain.info my wallet works just how bitcoin works. The private key behind an address is the key to spending the coins in that address. A wallet is just a collection of private keys and anyone who has had access to a wallet has those private keys. So there is no question of transferring wallets. Not even those that do contain private keys.
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