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Topic: The cost of Bitcoin attacks (Read 1758 times)

sr. member
Activity: 412
Merit: 287
October 27, 2015, 10:27:49 AM
#23
Check the blockchain.info page on blockchain forks. You'll see one-block-deep forks happen all the time. Your application needs to be able to undo a 'successful payment' because reorgs occur.

Should a certain someone Wink have his signature malleator running, a transaction with TXID A that confirmed in block A might have a different TXID if block B replaces block A.

So you have to be able to totally undo a successful transaction if the tip changes and orphans any block you have that includes a payment.
legendary
Activity: 1260
Merit: 1019
October 27, 2015, 08:47:20 AM
#22
It's near impossible to get a double transaction with even 1 confo.
yes. in mainnet. today
legendary
Activity: 1232
Merit: 1030
give me your cryptos
October 27, 2015, 06:13:57 AM
#21
It's near impossible to get a double transaction with even 1 confo.

Just think about the usual 3 confos... Jeez!
legendary
Activity: 1778
Merit: 1043
#Free market
October 25, 2015, 10:03:54 AM
#20
you would need to fork the blockchain. i'm sure he cant do it.
I can not do it today on mainnet.
I haven't said that it is impossible always.

Maybe tomorrow?
hero member
Activity: 935
Merit: 1002
October 25, 2015, 09:51:47 AM
#19
you would need to fork the blockchain. i'm sure he cant do it.
I can not do it today on mainnet.
I haven't said that it is impossible always.
All you need is just a simple orphan block.
legendary
Activity: 1260
Merit: 1019
October 25, 2015, 09:46:37 AM
#18
you would need to fork the blockchain. i'm sure he cant do it.
I can not do it today on mainnet.
I haven't said that it is impossible always.
legendary
Activity: 2464
Merit: 1145
October 25, 2015, 09:23:56 AM
#17
Can you make a test?
This is my address bitcoin 1GkGt3218AM8FU7ZGDCeZS4LWZR8xeZcjf  send me a PM once you'll start.
Not today, man.
On mainnet.
We can test this on testnet or on altcoin network.


Why not the real BTC blockchain?

because he cant.

He said I'm wrong, but you can't double spend a 1 conf. BTC transaction. It's real impossible  Roll Eyes.

you would need to fork the blockchain. i'm sure he cant do it.
legendary
Activity: 1778
Merit: 1043
#Free market
October 25, 2015, 09:21:55 AM
#16
Can you make a test?
This is my address bitcoin 1GkGt3218AM8FU7ZGDCeZS4LWZR8xeZcjf  send me a PM once you'll start.
Not today, man.
On mainnet.
We can test this on testnet or on altcoin network.


Why not the real BTC blockchain?

because he cant.

He said I'm wrong, but you can't double spend a 1 conf. BTC transaction. It's real impossible  Roll Eyes.
legendary
Activity: 2464
Merit: 1145
October 25, 2015, 09:04:37 AM
#15
Can you make a test?
This is my address bitcoin 1GkGt3218AM8FU7ZGDCeZS4LWZR8xeZcjf  send me a PM once you'll start.
Not today, man.
On mainnet.
We can test this on testnet or on altcoin network.


Why not the real BTC blockchain?

because he cant.
hero member
Activity: 935
Merit: 1002
October 25, 2015, 08:46:14 AM
#14
Can you make a test?
This is my address bitcoin 1GkGt3218AM8FU7ZGDCeZS4LWZR8xeZcjf  send me a PM once you'll start.
Not today, man.
On mainnet.
We can test this on testnet or on altcoin network.
Do it on litecoin/dogecoin network.Are you going to orphan block that included your transaction?
legendary
Activity: 1778
Merit: 1043
#Free market
October 25, 2015, 08:37:05 AM
#13
Can you make a test?
This is my address bitcoin 1GkGt3218AM8FU7ZGDCeZS4LWZR8xeZcjf  send me a PM once you'll start.
Not today, man.
On mainnet.
We can test this on testnet or on altcoin network.


Why not the real BTC blockchain?
legendary
Activity: 1260
Merit: 1019
October 25, 2015, 08:34:35 AM
#12
Can you make a test?
This is my address bitcoin 1GkGt3218AM8FU7ZGDCeZS4LWZR8xeZcjf  send me a PM once you'll start.
Not today, man.
On mainnet.
We can test this on testnet or on altcoin network.
legendary
Activity: 1778
Merit: 1043
#Free market
October 25, 2015, 07:26:39 AM
#11
However, you can't double spend a tx once it has 1 or more confirmation.
wrong

Can you make a test?
This is my address bitcoin 1GkGt3218AM8FU7ZGDCeZS4LWZR8xeZcjf  send me a PM once you'll start.



Good luck !
legendary
Activity: 1260
Merit: 1019
October 25, 2015, 07:21:16 AM
#10
However, you can't double spend a tx once it has 1 or more confirmation.
wrong
legendary
Activity: 1778
Merit: 1043
#Free market
October 24, 2015, 04:04:19 PM
#9
How much does it costs, for an attacker to double spend a coin at:

0 confirmations
1 confirmation
...
?

Trying to get some borders for buyers to wait, so the double spend doesnt happen.

Thanks

To double spend (send two times the 'same' TX) you have only to use a custom client (the RbF -replace by fee | bitcoinCore). However, you can't double spend a tx once it has 1 or more confirmation.
i remember seeing this video on youtube that explained that double spending can have more than 1 confirmation but the two tx would have to be confirmed at the same time? but the chances are very low of that happening. Does it work like that or if you double spend theres a 0% chance of both of them getting 2 confirmations each?


It is impossible to get confirmed the 2 transactions (double spend). Because for a successful double spend one of the two tx must not be confirmed, this is how it works.
hero member
Activity: 756
Merit: 500
October 24, 2015, 03:26:55 PM
#8
How much does it costs, for an attacker to double spend a coin at:

0 confirmations
1 confirmation
...
?

Trying to get some borders for buyers to wait, so the double spend doesnt happen.

Thanks

To double spend (send two times the 'same' TX) you have only to use a custom client (the RbF -replace by fee | bitcoinCore). However, you can't double spend a tx once it has 1 or more confirmation.
i remember seeing this video on youtube that explained that double spending can have more than 1 confirmation but the two tx would have to be confirmed at the same time? but the chances are very low of that happening. Does it work like that or if you double spend theres a 0% chance of both of them getting 2 confirmations each?
copper member
Activity: 1498
Merit: 1528
No I dont escrow anymore.
October 24, 2015, 11:51:52 AM
#7
Is this something that could be possible when a person is buying goods <100$? In a physical store.

Its possible, but you should read this thread -> https://bitcointalksearch.org/topic/double-spending-how-to-1197567
staff
Activity: 3458
Merit: 6793
Just writing some code
October 24, 2015, 08:39:24 AM
#6
Is this something that could be possible when a person is buying goods <100$? In a physical store.
Theoretically, yes. They would need custom software on their mobile device that would allow them to spend the same inputs again and with a different fee.
hero member
Activity: 560
Merit: 501
October 24, 2015, 06:57:07 AM
#5
Is this something that could be possible when a person is buying goods <100$? In a physical store.
legendary
Activity: 1778
Merit: 1043
#Free market
October 24, 2015, 06:52:37 AM
#4
So you can double spend a 0 confirmation transaction with no cost? Shocked

You have to put & spend the correct fee(s), and choose the 'right' inputs.
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