Where To Find Exact Confirmation Time?

[Hayati]

I want to create a simple game, people deposit into address and post on a thread. They guess at what time their transaction will be confirmed, the first person to guess their transaction time correctly wins everything inside the deposit address. (Minimum transaction 0.001 BTC)

I know blockchain.info shows how many confirmations and lots of other information about a transaction but how do I find out the exact time a transaction was confirmed?

[Cereberus]

I want to create a simple game, people deposit into address and post on a thread. They guess at what time their transaction will be confirmed, the first person to guess their transaction time correctly wins everything inside the deposit address. (Minimum transaction 0.001 BTC)

I know blockchain.info shows how many confirmations and lots of other information about a transaction but how do I find out the exact time a transaction was confirmed?

I am afraid this option is not available yet in the block explorers website. Because no one cares about such games and people only like to check whether their transaction have received the confirmations they need for different websites. So far block explorers only show the received times and nothing more. I don't think this option will be implemented anytime soon.

[DannyHamilton]

It cannot be done.

Bitcoin is a decentralized system with no accurate built in clock.

Therefore it is impossible for anyone other than the person that solved the block to know exactly when the block was solved (and if that person doesn't have an accurate clock, then even they won't know).

Bitcoin does not use time to determine the ordering of transactions.  Time is irrelevant to bitcoin for anything other than adjusting the mining difficulty (and a time within a margin of error of a few hours is fine for that purpose).

Instead, bitcoin uses blocks and proof-of-work for ordering transactions.  As such, you can tell that a transaction was confirmed AFTER some other transaction by the fact that it is in a block with a higher block height without ever needing to know when either of the transactions occurred.

Block explorer services will generally do one of 2 things when reporting a block time.

Either they will report the timestamp that the miner, or pool, embedded in the block when they created it (which was done BEFORE the block was solved, and which the miner or pool has the ability to set significantly differently than the actual time).

Or they will report the time (according to the service's clock) that the service first received the block relayed to them from a peer (which may be much later than the block was actually solved).

[krisnt80]

Sounds a great opportunity people does like to gambling and this might be just another option for them to play with their bitcoins if this wil be done let me know later.

[Hayati]

It cannot be done.

Bitcoin is a decentralized system with no accurate built in clock.

Therefore it is impossible for anyone other than the person that solved the block to know exactly when the block was solved (and if that person doesn't have an accurate clock, then even they won't know).

Bitcoin does not use time to determine the ordering of transactions.  Time is irrelevant to bitcoin for anything other than adjusting the mining difficulty (and a time within a margin of error of a few hours is fine for that purpose).

Instead, bitcoin uses blocks and proof-of-work for ordering transactions.  As such, you can tell that a transaction was confirmed AFTER some other transaction by the fact that it is in a block with a higher block height without ever needing to know when either of the transactions occurred.

Could I not build a script to listen to blockchain and award winners who are correct within 60 seconds of their guess?

[DannyHamilton]

Could I not build a script to listen to blockchain and award winners who are correct within 60 seconds of their guess?

You could, but you'd have two significant problems.

1.  If you used the time (according to your own clock) that you first hear about the block from a peer, then players in your game will need to trust you to report that time accurately.  You could easily adjust the time by a minute or two if it helps you or your friends win.  Therefore most players will suspect that you are mis-reporting the time (especially when that time doesn't match the timestamp in the block, which will be most of the time).

2. If you use the timestamp in the block, then miners and mining pools will have an incentive to play your game and adjust the timestamps in their blocks to match exactly what their guess is.  That way, they guarantee that they will win every time and will increase their mining revenue.  Why would ANY non-miner play in this game, since they are really just making a donation to the miner that solves the block?  Any miner that solves less blocks than another miner won't play either, since they are just contributing a percentage of their revenue to the miner that solves the most blocks.  The only miner that will play will be the miner that solves the most blocks, and he'll only play if you are paying more in winnings than he is betting.

[Hayati]

Could I not build a script to listen to blockchain and award winners who are correct within 60 seconds of their guess?

You could, but you'd have two significant problems.

1.  If you used the time (according to your own clock) that you first hear about the block from a peer, then players in your game will need to trust you to report that time accurately.  You could easily adjust the time by a minute or two if it helps you or your friends win.  Therefore most players will suspect that you are mis-reporting the time (especially when that time doesn't match the timestamp in the block, which will be most of the time).

2. If you use the timestamp in the block, then miners and mining pools will have an incentive to play your game and adjust the timestamps in their blocks to match exactly what their guess is.  That way, they guarantee that they will win every time and will increase their mining revenue.  Why would ANY non-miner play in this game, since they are really just making a donation to the miner that solves the block?  Any miner that solves less blocks than another miner won't play either, since they are just contributing a percentage of their revenue to the miner that solves the most blocks.  The only miner that will play will be the miner that solves the most blocks, and he'll only play if you are paying more in winnings than he is betting.

Yeah, I don't think people will trust me enough to do that because I am new.

Could I instead award the first person to guess the last letter or number of their tx id instead?

[DannyHamilton]

Yeah, I don't think people will trust me enough to do that because I am new.

Could I instead award the first person to guess the last letter or number of their tx id instead?

I can write a program that creates a transaction but does not broadcast it.

I can then look at the transactionID of the transaction and know exactly what it is.  If I like the ID (it matches a guess), then I can send it.  If I don't like the ID, I can just delete it without ever sharing it on the network.  I can generate millions of transactions like that every second until I get one that matches whatever I need to win.  Then I can make sure that I win EVERY TIME that I play your game.