Cheaters (double spenders) and what the gambling sites are doing against them

[gizane]

You could do what luckyb.it does and wait for it to confirm with a low fee, or have instant play with a fee of at least 0.0002BTC. Should stop most double spenders, as it needs to be a large tx size for it to not confirm for a while with that kind of fee. Most players won't really notice a difference with paying 4 cents extra for the fee if they can play instantly, but it protects you a lot more. It also shouldn't affect the people that like small fees, since they can choose to wait for it to confirm.

When the network is under heavy stress or under stress tests even the 0.0002 BTC fee may take some time to be included in a block.


It is an improvement, but of course not the solution for everything

That's correct, we've seen confirmations take up to an hour with the recommended fees!

If there are no new blocks you can wait 1 hour even if you put 1 bitcoin fee

Which is exactly why we would rather do a 0 confirmation deposit policy. However safety must always come first I guess!

Yes it is true that safety must come first but if people wait too long just to deposit, how secure your site is they wont come to play because need need fast deposit. I think safety and confirmation of deposit need to be balance so this will attract more people

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[BitcoinBlackjack]

It seems like we got the answers we were looking for. For now the 1 confirmation deposit policy will remain!
If any other website owners are having similar issues with 0 confirmations, I encourage you to do the same and protect yourselves from the cheaters.

[DogecoinMachine]

Yep, we switched to 1 confirmation deposit also. We had one double spent deposit with 20k satoshi fee.It's not really safe to allow instant deposits with higher fees.

[gyo9i]

Yep, we switched to 1 confirmation deposit also. We had one double spent deposit with 20k satoshi fee.It's not really safe to allow instant deposits with higher fees.

What was transaction size? 0.0002 per kb?

[LFC_Bitcoin]

Not many people have the intelligence or know how to be able to double spend. It is a pretty disgusting thing to do though. People shouldn't try & pull those kind of dishonest tricks

[DogecoinMachine]

Yep, we switched to 1 confirmation deposit also. We had one double spent deposit with 20k satoshi fee.It's not really safe to allow instant deposits with higher fees.

What was transaction size? 0.0002 per kb?

It was fixed 0.0002 btc per 1 BTC.

[cjmoles]

Well, I might add that the same type of scenario played out in the credit card taking online casinos.  I've witnessed it many times.  A person would credit his account with his credit card, make very risky wagers hoping for a large return, and if they'd lose, they'd just refute the charges on their card.  Of course, if they won, they'd just allow the charge to go through and then withdraw their winnings.

Mandating a one confirmation standard for bitcoin before wagering is allowed is quite generous....allowing a zero confirmations standard is the same as allowing credit so that's a risk....gambling with credit is very risky for several reasons.  And, it's not a good practice to permit.

[BitcoinBlackjack]

Well, I might add that the same type of scenario played out in the credit card taking online casinos.  I've witnessed it many times.  A person would credit his account with his credit card, make very risky wagers hoping for a large return, and if they'd lose, they'd just refute the charges on their card.  Of course, if they won, they'd just allow the charge to go through and then withdraw their winnings.

Mandating a one confirmation standard for bitcoin before wagering is allowed is quite generous....allowing a zero confirmations standard is the same as allowing credit so that's a risk....gambling with credit is very risky for several reasons.  And, it's not a good practice to permit.

Very good comparison! Thanks for the feedback

[BoXXoB]

As far as I am aware LuckyB.it system is pretty flawless as it is.


Currently the precautions they take (that I am aware of) are:

-0.0002 fee per KB with always a minimum fee of 0.0002 for instant bets
-Unconfirmed inputs must have 0.0002 fee per KB also
-The transaction must not have a malformed signature or a RBF-enabled one
-Transaction must not have output of less than 5460 satoshi

(credits to stingleword for the more detailed information)

Besides that they will not go into detail regarding the algorithm they have

[gyo9i]

As far as I am aware LuckyB.it system is pretty flawless as it is.


Currently the precautions they take (that I am aware of) are:

-0.0002 fee per KB with always a minimum fee of 0.0002 for instant bets
-Unconfirmed inputs must have 0.0002 fee per KB also
-The transaction must not have a malformed signature or a RBF-enabled one
-Transaction must not have output of less than 5460 satoshi

(credits to stingleword for the more detailed information)

Besides that they will not go into detail regarding the algorithm they have

It seems pretty safe and if something is not looking good they will delay bet until it is confirmed

[JasonXG]

Double spending is so very difficult to do, if at all. I wouldn't even be worried about it. I mean when's the last time this has even happened ? I haven't heard of double spending forma very long time.

[DarkStar_]

Double spending is so very difficult to do, if at all. I wouldn't even be worried about it. I mean when's the last time this has even happened ? I haven't heard of double spending forma very long time.

Umm, pretty recently? Double spending happens every day, and most people don't really look into it. Why bother anyway? Blockchain.info has a list of all double or triple spent transactions, I will see if I can find it. Double spending is definitely possible and even if it happens infrequently, it must suck for the gambling site owner to have to pay out a win that could have easily been double spent if he lost.

[BitcoinHodler]

Double spending is so very difficult to do, if at all. I wouldn't even be worried about it. I mean when's the last time this has even happened ? I haven't heard of double spending forma very long time.

Umm, pretty recently? Double spending happens every day, and most people don't really look into it. Why bother anyway? Blockchain.info has a list of all double or triple spent transactions, I will see if I can find it. Double spending is definitely possible and even if it happens infrequently, it must suck for the gambling site owner to have to pay out a win that could have easily been double spent if he lost.

there is nothing to find it is literary on the first page of blockchain.info
https://blockchain.info/double-spends

and i gotta say this is not a serious thing, nor a common thing that happens. look at this page and look at the dates and times the newest one is from yesterday. so it is not like people are double spending thousands of tx!!

also i should add that from all that list not all are fraud. there are times where you double spend to include more fees for your tx to get confirmed.

p.s. this is avoidable easily with 1 confirmation requirement.

[Avirunes]

Well i think better way to deal out is to stop the withdrawal or payout(onchain) until the deposit by a user/player gets 1 confirmation or further more confirmations that a site owner is suitable with.Also same should be with account balance transfer.Most of the sites uses that to prevent loss of double -spending

[DarkStar_]

Well i think better way to deal out is to stop the withdrawal or payout(onchain) until the deposit by a user/player gets 1 confirmation or further more confirmations that a site owner is suitable with.Also same should be with account balance transfer.Most of the sites uses that to prevent loss of double -spending

It seems you don't really understand what people are actually discussing about. The problem isn't withdrawing a double spent deposit, but rather people depositing money that can be easily double spent, gambling with it a risky way (like going 2x with his entire balance). If the bet wins, then he will let the deposit confirm and not double spend it. If he loses, he double spends the transaction and even though he lost money, he didn't actually lose it because he changed the transaction, and the gambling site owner gains nothing, but has a chance to lose money.

Double spending is so very difficult to do, if at all. I wouldn't even be worried about it. I mean when's the last time this has even happened ? I haven't heard of double spending forma very long time.

-snip-

there is nothing to find it is literary on the first page of blockchain.info
https://blockchain.info/double-spends

and i gotta say this is not a serious thing, nor a common thing that happens. look at this page and look at the dates and times the newest one is from yesterday. so it is not like people are double spending thousands of tx!!

also i should add that from all that list not all are fraud. there are times where you double spend to include more fees for your tx to get confirmed.

p.s. this is avoidable easily with 1 confirmation requirement.

I didn't look for it yet, since I was on my phone and it's hard to look for stuff on the mobile version. It is a serious thing for gambling site owners. Sure, it might not be done everyday, but one person could do a deposit with 1 bitcoin, double spend if he loses, but he could try bets like 10x, which would allow the casino owner a chance to lose 9 bitcoin with a very low chance for reward (the double spend fails). Even if it's done once every week, it still hurts.

[LoyceV]

As a player, I understand the need for at least one confirmation.
As a Mod on a dice site, I often see people wonder why their deposit takes so long. Especially when it takes a long time to find the next block.
Unfortunately, there is nothing to do about this, other than using a faster altcoin or changing the fundamentals of Bitcoin. Both aren't really an option.

Don't forget that Sathoshi's original recommendation is to wait for 6 confirmations before you can fully trust the transaction. One confirmation is already moving far towards a better user experience instead of full security. I know at least one exchange that requires 6 confirmations before you can trade.

[Abitcoinbetter]

Hi, new member here, but not new to btc casinos.

I remember one time playing at mbitcasino 1 of my deposits for .5 btc got double spent and I have no idea how. I had no clue it got double spent as I lost the entire deposit. Months later, after many more deposits I finally won but they would not let me cashout.  When I contacted support they said a deposit from months ago was "double spent" and never went through.

They wanted the .5 btc taken out of my current winnings because some deposit from over a month ago supposedly got double spent and never went through. I was pissed to say the least, especially since I've deposited 20+ BTC over the past year or so, without incident.

It literally took 1 month to straighten out and in the end they did not make me repay the .5 btc. To be fair, they even credited my account .5 btc without playthrough for the hassle.

I did not do the double spend and they a knowledge that. Has anyone ever heard of anything like this before? I mean, the supposed double spend deposit they never received was played and lost.  They continued to allow me to deposit and lose and the 1 supposed double spend only came to attention when I tried cashing out.

This might be a little confusing. If so I can provide corresponding emails I had with mbit at the time...

[BitcoinBlackjack]

Double spending is so very difficult to do, if at all. I wouldn't even be worried about it. I mean when's the last time this has even happened ? I haven't heard of double spending forma very long time.

It was happening for us nearly every day. These cheaters are professionals that do this for a living.

[lister storm]

they just ask people for confirmations when they make a deposit because i doubt it is possible to cheat with the deposits though that is just my thoughts

[bapparabi]

OMG now day how all hacker and user try to find way to trick the website to get bitcoin ..in anyway they can ..so this i quite good finding ..hope like this new trick will be found and taken action to stop it