Bitcoin Forum

DoubleDownBTC is a new provably fair Blackjack game.  We feature 99.6% expected return, zero confirmation deposits, instant payouts, no registration and extremely player friendly rules.

For a limited time we are offering a 20% bonus on all initial BTC deposits!!! Just visit https://doubledownbtc.com and make an initial deposit.  PM me your generated BTC deposit address and we'll add 20% of your first deposit, up to 1 BTC.

Thanks for playing and good luck!!


fine print:
The promotion is 20% on initial deposits. Initial deposit can be withdrawn instantly, the bonus 20% can be withdrawn after 20x play. You must PM to request this promotion.

I like the autoplay feature. Is there a way you can prove that that's not rigged?

I actually just found a bug for the autoplay. I had 8s (dealer had 9) and it split them. I drew a 7 and the game stopped and my browser showed an error message.

Thanks for the bug report!


You can look at the JavaScript if you like, or just take a look at the bottom of the page where your play history scrolls by, you can click the VERIFY button next to any row to check the provably fair data.

Thanks.  The shuffle *should* be truly random.  Would you mind PM'ing me your account key? I'd like to check your play history for any patterns in the shuffles.

Much appreciated.

check your pm good sir ;)
or adress: 1PjXbUk3GpTEmKwcWy2FSE1AVHaiw1iu3N


will give feedback

My address: 1BYqikXWtmFQysqCbdCDDtXTDkGeVuCNGG

I will try it out and let you know how it is

Its got a nice feel to it. It has a general look of video blackjack that's played in a Vegas casino. I had a few glitches come up while playing that said my internet connection was lost when I know it wasn't. Overall, after playing some hands, it generally was pretty smooth. I was confused at the beginning with the term "DRAW" rather than "DEAL". I prefer the DEAL wording better. I'm sure after some time you'll get the kinks out.  ;)

Any BTC would be appreciated! Thanks!  

1P1A8ttw9KfPhaVLRjYoczNwqyq8pzuhhv

got the same error vouch

new address
14gkBQFhocVcKFrALaMA6GNMGkNtSRHttb


your max bet is 100 not 1000(error betting anything higher then 100 so i assume)
so typo in your site

Thanks,  all good reports.  I'll get the max bet fixed.  Also the bug in the provably fair checker seems to be related to taking insurance. It doesn't seem to be a problem with the game, just the fairness check.  I'll get that patched up quickly!

Also, I keep getting the Error message when requesting insurance. 2nd time already! I sent you a PM with my player Key# so you could look it over.

Best of Luck!

1P1A8ttw9KfPhaVLRjYoczNwqyq8pzuhhv

i pmed you waiting on the bonus :P
adress is 14gkBQFhocVcKFrALaMA6GNMGkNtSRHttb

I've never seen a video black jack in a casino. It really looks that ugly? (Or maybe I did, a long time ago, but I didn't pay attention.)

1B88kCTKogjZnGzCFZCuLQQUWZ146DmFZF

Another issue was the fact that I bet my last 38 credits and won the hand, but when I proceeded to hit the draw button, the "ADD CREDITS" box popped up and would not let me play any further without depositing BTC!

Looks like there's a small logic issue with the dialog.  If you refresh your browser, or wait a few seconds, you'll see the credits refresh.  Should be an easy fix for us.

Your right it did exactly that when I refreshed the browser!

Ill help out the address it says to send coins to is 1daeV1VA131hJTXhKDavrboPqjwSQ86Fq

Sent!  Thanks for playing.

Lose all that you gave , max i've gone to 32. I stand on17/18

Nice game indeed.
Suggestion: add keyboard shortcut. eg: H for hit and S for stand

Great idea on the keyboard shortcuts!

Give me a try:

13ZYt4tAd2LUSiY4ZSeZiCErox93eTgwf9

hmmm, I will pass, generally I don't play at sites that are completely ripoff of others. it's kinda shady.

https://bitcoinvideocasino.com/blackjack

Not trying to rip anyone off.  We coded this site up while BVC was down hard last week.  We honestly weren't sure if they were coming back and aimed to fill the void.  I think there's a shortage of good low house edge BTC games out there and I think that's a shame.

This is the version 0.1 interface and the frontend was arguably slapped together.  We're validating our backend infrastructure right now and trying to push as many games through the system as possible. Our auditor requires 100k unique game histories to certify our system. 

Don't worry, we're working on quite a few graphical improvements as we speak. But thanks for the good feedback.

DEPOSIT BITCOINS TO 1AP2YxH1RGw3dBfDhSXvnSbDCSrPCeUA3w

So I played this morning. Only error I got was when taking insurance and dealer had bj. Other that that no errors.

I did run the 50 credits to 700+. Cashed out at about 650 (.65btc.)

Instant cashout, and looks just like the video bj at the bar of casinos I've been in. I like it!

Ill be playing more later.

maybe if you looked at their thread, you wouldn't have doubts:



do you really need that?


You really should had started with this done.

I would love to take part.  

The deposit address I got is:

13rEdrURxsC9oehJrA4d2rhLkLfPqEf3c3

Ok I just played the bitcoin portion of the game. Thanks for the test account My Review:

Everything seems fair the hashes and results are displayed on the bottom instantly after each round. Blackjack pays the usual and the plus side is dealer stays on soft 17 (giving the player more of an advantage). Like I said before graphics look nice and site loads quick. Great job and Good luck with your website!

I like very much the BJ

I wish to try it.

18eVgXtJLwCdmnkVsBtg6529zPRRHAm85p

Thanks

Really fun site..only time it popped up an error message was when i would buy insurance..and another probkem i had was when i bookmarked the site and came back to it later it gave me a hole new deposit address..
So does that mean i get to try out the bonus coins again?? 1M6nJjsWEbE5e227FNTu7yEU4xgmN1EXet

You should also add a shortcut to double the previous bet. Martingale strategy is popular with blackjack.

will play and let you know if i come across any errors  ;)

1BJ9nLFyQB25VQPq9hfg4MpXafjY71WnkD

Sorry about that.  The bonus credits had expired because they weren't played.  I reset your account.

Thanks!

Great run!  Glad to hear!!

Sorry, In my opinion, your game sucks... Maybe it's just me raging, but I think that your game is not fair... I lost 5 times in a row, everytime your dealer got a +1 more than me.

OOpppps... i wrote a wrong bitcoin address.

I bookmarked now the site and it show me this address: 1JULu1ag7Ahr4j6gU41Uak9DEU5SMNguCg

Thank you


P.S.: i find it a bug... now i try to paste a screenshot

I will tell you if i find any troubles

my btc address from your site 1DmCKHdG7KdpXZaDYpiMM8KFm8c42uLVnh

!

DoubledownBTC... Look here

http://imgur.com/YU4LMHj
http://imgur.com/94BGRtN

In this game i picked up two aces and i decided to split.

In each game i made 21.

So, the winning correct is: 1 BET * 2 * 2 = 4 BET

In this case i won 4.5 BET

And appears this window ERROR... and the winning didn't accreditated

Thanks for reporting this. Looks like the ace-10 got scored as a blackjack. We'll clear they issue ASAP.

Thanks for everyone that helped with the bug catching.  We've published the updated version of our backend and are nearing the volume of play required to have our gaming engine externally certified.

As a thank you to the bitcointalk community, we're offering a 20% deposit bonus on all first time deposits.  Just PM me your account once you make your first deposit and I'll apply the bonus!

Thanks again for playing, and "good luck with that ace!"

20% on any and all first deposit ? Instant withdraw or some certain amount of games played is required ? Take care there.

Good question:
The promotion is currently listed as 20% on initial deposits. Initial deposit can be withdrawn instantly, the bonus 20% can be withdrawn after 20x play. Thanks for asking, I realized that wasn't listed on the original post.

Critical bug found, sites bankroll at risk ( not player bankrolls). Advised owners to callme so I can describe. I'd hope they will offer a bounty also.  I literally could have taken whole site backroll. Please call or message asap.

Great catch. Appreciate that you reported this ethically. We confirmed that there was a bug that could in some cases cause a deposit to be credited more than once to an account. We have patched it and can verify that player funds were at no time at risk.

Your bounty will be on its way!

I spoke to a developer, and he was very professional. Glad to help. I really hope the site succeeds, and will be playing often here. Great people behind the scenes of this site.

Are you seriously just ripping off bitcoinvideocasino's website? You literally took their graphics, sounds, ...

For that reason alone I would not trust you guys

Is that proprietary software? Honestly had much better cards playing with this casino then bitcoinvideocasino. Wonder if there is an "on" and "off" switch for winning hands.

Well, it is clearly copyright infringement, which is of course illegal. The chance they will take legal actions is obviously nill, but that doesn't make it ok.

and what is PROVABLY FAIR?

your site type:

Game Seed == Server Seed + Client Seed:
19508405357028949

SHA-512(Game Seed) == Sent to client for verification:
8d3c98c78789d564c6f185b4bf0d939e11b74c78d2ea7455e8852bb21b18d7ff

but real SHA-512(19508405357028949) == "8f4a90956ee62a2a28bbaf1e49950867f13aa16ee03cade1b66f40099f35f3dc6b27c59afa4c9ff 0beaefd067d4125a7de10db4478450e98710d0c385cd59938"
and SHA-256(19508405357028949) == "9a9c23521ed79688918363f9e60ac5ad2365ec21cf4a71807d7ba84ffb3bd397"

 ::)

That's really strange. If you look at the JavaScript you'll see that your browser hashes the raw server seed we send at the end of the game and compares it to the hash of the server seed we sent before the game. If the two don't match an error is thrown.

Can you send me the gameid of a game where you don't think the hash matches? I'd like to investigate.

its for all my games same ...
but one game id:
GameID: 5236edc0154136a63dd024f9
Pre-Game
Server Seed == Random starting seed from server:
798084933
SHA-256(Server Seed) == Sent to client for verification:
34e567c2ccf6047c2ba90f69463c0f3d04bcf044d7f9525948fbf37b5090f312
Client Seed == Random number from client:
1440710446
Game Seed == Server Seed + Client Seed:
7980849331440710446
SHA-512(Game Seed) == Sent to client for verification:
8e81f67beb382de015fd1772b6d9cf99ef56e8d67225bccb81a5b006f8421b0b
Mersenne(Game Seed) == Final shuffled deck (first 52 cards):
qdadqsqh9ckctd6d6d7hksqh5dthkd5s3s3c3d9s8cjcth7dad4s

Another issue:

You charge .0005 on withdraws to cover miners fees....but you are sending out withdraws with only a .0001 miners fee, which is making all the withdraws take ages.....

I have withdrawn 3 times now, with this happening, and still have a little funds to withdraw when done.  So I have already paid .012 in fees that didn't go to the miners, and prolonged confirmations.  Can this get fixed?  Not too concerned about getting the funds back, more concerned that if I am having .005 deducted from my withdraws, I want it applied to the miners fee, so that I am not waiting hours to get a confirmation on the network.

Is there a max bet on the play chips? Keep getting an internal server error

100

I'm sorry about that, I'm looking into why that transaction didn't post.  I see the transaction though.  I've refunded the deposit to your address above, I would recommend trying a new account just to be safe.

It looks like our deposit queue got a little backed up (a good problem to have I guess), the transaction finally processed and there was nothing wrong with your account so you can keep using the same one. We've added another worker to our deposit process and the queue is back down to zero. Transactions should be posting instantly again. Sorry for the hassle with the long deposit delays!

We're flattered that you thought our casino was great enough to copy.

That being said, we always recommend that the community be diligent about the casinos they play on. We found that your stated return to player is 99.6%, but with the BJ rules we used (which you didn't change) the return to player is 99.5%. Our 99.6% comes from a .1% contribution to the progressive jackpot. You have no progressive jackpot, so where is that extra .1% going?

We also tried playing on your site but the deposit was never credited.

Thanks, our payout percentage was calculated using the wizard of odds calculator which gives us a house edge of 0.42945% which is technically 99.57055%  We rounded to 99.6, but it's a good point. The site has already been updated to be more accurate.

As for the deposit, let me know the BTC address and I'll investigate.  We use the blockchain.info API to verify confirmations.  There's been some weird problems with their service over the last 24 hours and we've seen a few transactions that aren't showing as confirmed even though they are.  We're going to be manually watching the queue until blockchain.info gets sorted out.

Refunded. 

We just stopped using the blockchain.info API to confirm transactions until whatever is wrong with their system is fixed.  If anyone else feels that a deposit hasn't credited, please drop me a note and I'll get it resolved.

Thanks!

They copied our CSS, Javacript and HTML without our permission.

But....

your site looks exactly like the video blackjack machines at every casino near me....

So......

Didn't you copy from THOSE COMAPNIES first?

We have performed an analysis of the provably fair code on DoubleDownBTC and believe that it is not legitimate. There is absolutely no guarantee that the shuffle generated is random, so they could be packing the deck in their favor.

Using the values from the provably fair dialog, when we try to manually generate the deck given the game seed, we get a different deck of cards. This means that on the server side it is not actually using this verification data. We suspect that the server is not following the rules of provably fair and is shuffling the deck however it wants.

GameID: 523d3d4915413651609f8cbf
Game Seed == Server Seed + Client Seed:
14593047563445106624089340932
Mersenne(Game Seed) == Final shuffled deck (first 52 cards):
kd8hjhah4d3c9c6h9hkskcjc7djdah7sahtdtc8c3hjd4skh2c2d

Can you please demonstrate how you were able to generate that deck of cards given that game seed?

The client-side Javascript function that verifies the deck shuffle has been purposely disabled. The function is called check_game(), and it is supposed to check that the deck that was actually played is the same as what the server committed to when it initially sent the server seed. However, after this function shuffles the deck, it then just cheats and manually sets the generated deck of cards to what the server dealt:

var game_cards = game_info_package.deal_hash_source.slice(1, first_close_paren);
check_cards_string = game_cards;
if (check_cards_string == game_cards) {
    proves_deck = true;

Essentially the code is generating the deck, but then setting check_cards_string to equal game_cards, so that the test will always pass. This means that the verify dialog will falsely tell you that the shuffle was legitimate, when it in fact was not.

To summarize, the server is not shuffling the deck in a provably fair way. The client code has been purposely disabled to not point out this error. Please be careful. We don’t want people getting scammed betting with their Bitcoins, especially on a site that looks almost identical to Bitcoin Video Casino.

Excellent catch.  Thanks for reporting that.  You are correct, the check logic in the JS is disabled, this seems to be a missed relic from testing.  The code is being corrected today. 

As for how we calculate the deck from the game seed:
It's pretty straight forward
We take the final game seed + the game seed hash, convert this to a string (which is a byte stream in PHP) and use it as the seed for the mt_srand function in PHP. This will seed the Mersenne Twister algorithm. We then perform a Fisher Yates shuffle on the shuffled deck, using the mt_rand function as the RNG. This adds two levels of randomness to the shuffle and provides a reproducible result after the fact.

In the essence of transparency we've decided to add a feature to the site which will allow anyone to download a public game history file each day which will show all games played, the server, client and game seed as well as the complete shuffled deck. This can be used to perform analysis on the dataset, or simply to verify a particular game again after the fact.

We are also in the processes of having our game engine externally audited which will add a further level of trust to our engine.

While I am happy that a developer let this test get into production, I can assure you that the games are random. Anyone that has a particular concern about the outcome of a game or the randomness of a shuffle, please contact any of us directly and we will provide the complete audit history of any game.

Thanks again for the great bug catch.

We find it hilarious that you speak of "a further level of trust" when you have blatantly stolen our HTML, CSS, Javascript, art and sound files, and claim provably fair blackjack yet actually have no such thing. The fact that you think any of this is OK is mind boggling.

We have worked hard to create a casino that is trustworthy and fun to play. We will continue to improve our site, and we hope that in the end, users will know which web sites they can trust their Bitcoins with.

I'm really concerned that you keep having these issues.  I've investigated the transaction and it doesn't look like it's been picked up by Coinbase yet.  The transaction you referenced is in block 260089, but coinbase, who we have been using as a temporary deposit processor since last weekend, is only reporting up to block 260029.  There seems to be a serious lag right now.

We moved to coinbase temporarily as a way to expedite deposits and confirmation verifications, this seems to be causing different issues.

Our developer is investigating an option to use our previous bitcoind solution. It doesn't look like there is a reliable thirdparty processor yet unfortunately.

Credit was sent back in txn Hash   fe751d7a34bd0479078e4f043c57a6f17d82ad92393f2c4d6a22dc847d334165

I withdrew .7+ thisorning, never got it...1DoNkCTUZKN9cmBf36uScwEEs74Zfev4ue is the address I withdrew to....

It looks like your transaction is still queued with Coinbase:

https://coinbase.com/network/transactions/d86482b91c946ddcfcc9e1be26761da09788f088a6bd817098ef1b5de37ca9a5

They seem to be taking awhile this morning.  We're thinking of putting a transaction history page on the site so you can track the txn's in and out.  I agree, it's never fun to wonder if your transaction disappeared.

Ok cool no rush. Just making sure it got sent. Can I have the 20% added to acct I played on?

Still haven't gotten my btc. You guys need to contact coinbase or something. Its going on 7 hours now....no reason I should be without my btc this long.

Do not deposit here, until they fix their cashing put issues.  I've been waiting almost 8 hours, for a withdraw. They have offered zero assistance, have not contacted their cashout provider coinbbase, nothing.

We have a ticket open with Coinbase, there are multiple transactions held up with them right now.  We cannot cancel the transaction at this point because it's already been accepted, We can process any future cashouts manually until Coinbase gets back in sync with the rest of the blockchain.

Future cashouts doesn't help that I've got my last .75 btc in limbo.  This isn't a new issue, coinbase made a post about it yesterday, yet you still are sending cashouts their way. This is new....previously they were all instant. Figures, the time I make a largish deposit and withdraw, therws issues holding it up for hours. If I don't have my btc in next 2 hours and I miss some vets on games I want to put in, I'm going to be very pissed off . 

Resolved

Resolved