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Topic: BTC Transaction time - page 2. (Read 2240 times)

legendary
Activity: 1260
Merit: 1019
September 28, 2014, 09:29:29 AM
#28
Quote
What about this vs this?
The two different transactions are broadcast at the same second (according to bc.i received time) and have 2 different destination addresses.

It is not a big problem to create two (three, four...) transactions to different addresses and send them in one second to different nodes.

Quote
It might have been an experiment of sorts
Definetely yes.
copper member
Activity: 1498
Merit: 1520
No I dont escrow anymore.
September 28, 2014, 09:28:15 AM
#27
What about this vs this?
The two different transactions are broadcast at the same second (according to bc.i received time) and have 2 different destination addresses.

Perhaps the "wording" used in blockchain.info could be better (i.e. "double-spend attempt" vs. "double-spend").


Yes, my problem is basically that for me a double spend would be if one of the TX had at least one confirmation, but I cant tell how common this idea is.


-snip-
While double-spending is rare, I don't think it is that rare.
You can take a look at https://blockchain.info/double-spends to check the latest 20 double-spending attempts.

People generally have different ideas of what a double spend actually is. I have no idea what this list by bc.i want to tell me, most of the TXs look pretty normal.

What about this vs this?
The two different transactions are broadcast at the same second (according to bc.i received time) and have 2 different destination addresses.

This looks interesting. The time is not relevant though. Its just the time bc.i received the TX. They however spend the exact same inputs. It might have been an experiment of sorts, since one was transmitted to bc.i from a node in germany and the other one from a node in japan and the amount of BTC transfered is very low.

Code:
{"double_spend":true,"block_height":322877,"time":1411876758,"inputs":[{"sequence":4294967295,"prev_out":{"n":0,"value":30000,"addr":"15KUh45rrsDWxffxyAvNtZZqivA3uuSWT2","tx_index":65485082,"type":0,"script":"76a9142f5f1af9b3dc4806d8f4b11aa5fb880d18b12da988ac"},"script":"483045022100eec570ea9dd29d0c25be3f56cf5e13f3be53e129e16f63d032c0b817ed1e9f0c0220344bfe30580bfe3e255a80c321694fceed28061692e045918cc25ef7d4ef4f9d01410400d81973c54901ea63f2fe2b5214f707dbac4e5c499ad1364d8148ee9c93663bded0f86c0f6ceaa2747d8ad4034dfeea781c9b16f202f22e76cfe64f01d49980"}],"vout_sz":1,"relayed_by":"106.187.96.219","hash":"1ae0763c896d1da162c7be8c998970231c5b38786db0ec93e6efc6cdd7d240a9","vin_sz":1,"tx_index":65484044,"ver":1,"out":[{"n":0,"value":10000,"addr":"1tokyoKz3RTWDNVLdGCBjEHkdvbAxh9rm","tx_index":65484044,"spent":true,"type":0,"script":"76a91409cc3ef2423ff7d0c3552d6b2b8efdcfef7c8fbb88ac"}],"size":224}

Code:
{"double_spend":true,"time":1411876758,"inputs":[{"sequence":4294967295,"prev_out":{"n":0,"value":30000,"addr":"15KUh45rrsDWxffxyAvNtZZqivA3uuSWT2","tx_index":65485082,"type":0,"script":"76a9142f5f1af9b3dc4806d8f4b11aa5fb880d18b12da988ac"},"script":"483045022100a96c1da1bc72172180ebab6ef9837727c065f851d50813059f188ada07c19faf022018365f048eab41617ab706c2e62f1379e1918d1fa26f0c163a1ff8f4248ddb7a01410400d81973c54901ea63f2fe2b5214f707dbac4e5c499ad1364d8148ee9c93663bded0f86c0f6ceaa2747d8ad4034dfeea781c9b16f202f22e76cfe64f01d49980"}],"vout_sz":1,"relayed_by":"5.9.104.212","hash":"9ea1dc2e2d9dca8e66022df9d63f4922e2ee92ad2354db1d6b3128d8b71cd7bd","vin_sz":1,"tx_index":65484042,"ver":1,"out":[{"n":0,"value":10000,"addr":"1o24eTapXpEWZcPi1B3JDegjDuhWPauN7","tx_index":65484042,"spent":true,"type":0,"script":"76a91408b4057f38740cc77c3b15c2e9e3ca81a9c26a1188ac"}],"size":224}
legendary
Activity: 1890
Merit: 1078
Ian Knowles - CIYAM Lead Developer
September 28, 2014, 09:21:57 AM
#26
What about this vs this?
The two different transactions are broadcast at the same second (according to bc.i received time) and have 2 different destination addresses.

Perhaps the "wording" used in blockchain.info could be better (i.e. "double-spend attempt" vs. "double-spend").

Of course until at least 1 confirmation has occurred it is impossible for them to identify which one is the one that "will go through" (apart from perhaps guess by looking at the tx fee which would not have helped in this case - but they should probably change the wording after x confirmations as the other is never going to confirm then).

Note that https://blockchain.info/tx-index/65484044 has 47 confirmations (so it is a *real* tx) whereas https://blockchain.info/tx-index/65484042 has no confirmations (and is never going to get any unless Bitcoin has a major disaster).
sr. member
Activity: 406
Merit: 250
September 28, 2014, 09:16:30 AM
#25
-snip-
While double-spending is rare, I don't think it is that rare.
You can take a look at https://blockchain.info/double-spends to check the latest 20 double-spending attempts.

People generally have different ideas of what a double spend actually is. I have no idea what this list by bc.i want to tell me, most of the TXs look pretty normal.

What about this vs this?
The two different transactions are broadcast at the same second (according to bc.i received time) and have 2 different destination addresses.
legendary
Activity: 1890
Merit: 1078
Ian Knowles - CIYAM Lead Developer
September 28, 2014, 09:14:13 AM
#24
Yes - the term "double spend" seems to imply that someone "spending the same BTC twice" has been recorded in the blockchain (but no such event has or *can* occur - because if it *could* then Bitcoin would be *pointless*).

What the term is generally referring to is a "double-spend attempt" whereby one tx spending certain UTXO's can end up being "replaced" by another (most usually when 0 confirmations have occurred - and in fact I'm not aware of any such events happening when there was 1 or more confirmations although potentially that might have happened we had the "fork" back in early 2013).

The easiest way to perform such an attack is to provide *no fee" in the initial tx and provide a "generous fee" in the "replacement tx".

Depending upon how you do this it can be actually successful (and is not so hard) so it is never advised for vendors to accept zero confirmations (especially those without any fee).
copper member
Activity: 1498
Merit: 1520
No I dont escrow anymore.
September 28, 2014, 09:10:28 AM
#23
-snip-
Or, the supermarket will accept your 0-confirmation bitcoin transaction as long as it has minimum fee attached.
Double-spending is extremely hard unless you have a significant proportion of network hashrate, and so it is very very unlikely a casual supermarket customer has the ability to double-spend successfully.

As far as I know, there hasn't been a double spend in over 2 years. I doubt there will be one ever again.

This all depends on what you understand as "double spend". Its especially hard if you want to revoke a confirmation (">50%-attack"), which seems not to be the case here. Why be afraid of a 1 confirmation revoke if you are talking about 0 confirmation TX?

Anyway a 0 confirmation TX can be "double spend"* if the TX is badly propagated through the network and has a low or no fee. In this case it would be possible to generate another TX that spends the same inputs but pays a (higher) fee and uses a full node with plenty connections to broadcast it to the network.
This is indeed nothing a casual supermarket customer would or could pull off. On the other hand the supermarket could demand a fee on the TX and set up several nodes to see how good the TX has been propageted to make a possible doublespend even harder.


* its not actually spend twice, but for the sake of the argument lets call it that.

-snip-
While double-spending is rare, I don't think it is that rare.
You can take a look at https://blockchain.info/double-spends to check the latest 20 double-spending attempts.

People generally have different ideas of what a double spend actually is. I have no idea what this list by bc.i want to tell me, most of the TXs look pretty normal.
sr. member
Activity: 406
Merit: 250
September 28, 2014, 09:05:17 AM
#22
How is regular shoping going to work if it takes a while to confirm? like you go to a supermarket with your phone and then pay, what happens if you have to wait to get it confirmed??

One way is off-blockchain transactions.  So if then exchange had a deal to be a processor for the supermarket and you can send funds from your Exchange account so it all happens within the exchange.  There could also be deal to use "green addresses" where your online wallet sending address is trusted by the supermarket.  So if you sent funds from your exchange wallet and the supermarket trusts the exchange. 

Or, the supermarket will accept your 0-confirmation bitcoin transaction as long as it has minimum fee attached.
Double-spending is extremely hard unless you have a significant proportion of network hashrate, and so it is very very unlikely a casual supermarket customer has the ability to double-spend successfully.

As far as I know, there hasn't been a double spend in over 2 years. I doubt there will be one ever again.

While double-spending is rare, I don't think it is that rare.
You can take a look at https://blockchain.info/double-spends to check the latest 20 double-spending attempts.
legendary
Activity: 3052
Merit: 1273
September 28, 2014, 08:35:45 AM
#21
How is regular shoping going to work if it takes a while to confirm? like you go to a supermarket with your phone and then pay, what happens if you have to wait to get it confirmed??

One way is off-blockchain transactions.  So if then exchange had a deal to be a processor for the supermarket and you can send funds from your Exchange account so it all happens within the exchange.  There could also be deal to use "green addresses" where your online wallet sending address is trusted by the supermarket.  So if you sent funds from your exchange wallet and the supermarket trusts the exchange. 

Or, the supermarket will accept your 0-confirmation bitcoin transaction as long as it has minimum fee attached.
Double-spending is extremely hard unless you have a significant proportion of network hashrate, and so it is very very unlikely a casual supermarket customer has the ability to double-spend successfully.

As far as I know, there hasn't been a double spend in over 2 years. I doubt there will be one ever again.
sr. member
Activity: 406
Merit: 250
September 28, 2014, 07:26:07 AM
#20
How is regular shoping going to work if it takes a while to confirm? like you go to a supermarket with your phone and then pay, what happens if you have to wait to get it confirmed??

One way is off-blockchain transactions.  So if then exchange had a deal to be a processor for the supermarket and you can send funds from your Exchange account so it all happens within the exchange.  There could also be deal to use "green addresses" where your online wallet sending address is trusted by the supermarket.  So if you sent funds from your exchange wallet and the supermarket trusts the exchange. 

Or, the supermarket will accept your 0-confirmation bitcoin transaction as long as it has minimum fee attached.
Double-spending is extremely hard unless you have a significant proportion of network hashrate, and so it is very very unlikely a casual supermarket customer has the ability to double-spend successfully.
hero member
Activity: 510
Merit: 500
September 27, 2014, 11:01:33 AM
#19
How is regular shoping going to work if it takes a while to confirm? like you go to a supermarket with your phone and then pay, what happens if you have to wait to get it confirmed??

One way is off-blockchain transactions.  So if then exchange had a deal to be a processor for the supermarket and you can send funds from your Exchange account so it all happens within the exchange.  There could also be deal to use "green addresses" where your online wallet sending address is trusted by the supermarket.  So if you sent funds from your exchange wallet and the supermarket trusts the exchange. 
newbie
Activity: 14
Merit: 0
September 27, 2014, 09:11:16 AM
#18
How is regular shoping going to work if it takes a while to confirm? like you go to a supermarket with your phone and then pay, what happens if you have to wait to get it confirmed??
full member
Activity: 434
Merit: 101
https://www.payaccept.net/
September 25, 2014, 12:46:54 AM
#17
it usualy takes ~ few minutes
hero member
Activity: 510
Merit: 500
September 24, 2014, 10:00:30 PM
#16
You are discussing 2 separate problems.

The first is the probability of getting your transaction accepted by a miner.  This depends on the individual miner requirements to accept transactions.  You can't really calculate this easily because it is up to the miners own internal rules.

The next part of the problem is the time waiting for the next block.  That is a random process.  First you have to get the probability of being included in a block from step one and then multiply it by the probability of finding the next block. If you want to do caculations see http://bitcoin.stackexchange.com/questions/8028/given-the-probability-of-finding-a-block-and-time-taken-can-i-infer-hashrate and https://bitcoil.co.il/pool_analysis.pdf
legendary
Activity: 1120
Merit: 1000
September 24, 2014, 09:19:20 PM
#15
I think this is one of the biggest problems to solve about bitcoin in the close future
legendary
Activity: 2296
Merit: 1014
September 24, 2014, 07:20:11 PM
#14
This is quite complicated, but i would assume personally that 1st confirmation is in 10 minutes around
legendary
Activity: 4354
Merit: 3260
September 24, 2014, 05:57:26 PM
#13
Why do block times vary? whats the variable that says, it will take this or that time to process? I dont get this.. i thought it all depended on, the miner fee or something.

The time is random, but is designed to an average of 10 minutes.
legendary
Activity: 868
Merit: 1004
September 24, 2014, 05:51:22 PM
#12
Why do block times vary? whats the variable that says, it will take this or that time to process? I dont get this.. i thought it all depended on, the miner fee or something.
copper member
Activity: 1498
Merit: 1520
No I dont escrow anymore.
September 23, 2014, 04:28:17 PM
#11
It takes ages unless you spend more than the default set miner fee. I think about 25 minutes at default fee.

I don't think that is true.
From my own experience, about 95% of my transactions with standard fee (0.0001/KB) are included in the next block and all the rest are included within the next 3 blocks.

Yes it makes no sense to pay above standard fee. AtheistAKASaneBrain probably has no clue that block times might vary.
hero member
Activity: 614
Merit: 500
September 23, 2014, 11:50:55 AM
#10
It takes ages unless you spend more than the default set miner fee. I think about 25 minutes at default fee.

I don't think that is true.
From my own experience, about 95% of my transactions with standard fee (0.0001/KB) are included in the next block and all the rest are included within the next 3 blocks.
hero member
Activity: 770
Merit: 509
September 23, 2014, 11:40:44 AM
#9
It takes ages unless you spend more than the default set miner fee. I think about 25 minutes at default fee.
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