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1  Economy / Gambling / Re: ▶Nolimits-Lottery.com - Provably fair, DAILY WEEKLY MONHLY draws. NO price limit on: September 10, 2013, 05:35:42 PM
I've added very interesting feature (as I think) - instant preview of the draw results - because server knows the secret it can simulate the draw like if it would stop right now and get results, so if you transaction is got confirmed, server will perform the computation and return results, so you can instantly see who will win if there would be no more transaction in this draw, and if there will be more transaction the results will be regenerated again and of course they will be completely different.

This can bring a very different feeling to the lottery, for example if you've made a large transaction and you have high odds to win, but currently there are other transactions winning, you can send a very small transaction just to "shuffle" the results.
2  Economy / Games and rounds / September 2013 draw at Nolimits-Lottery.com. New lottery. on: September 10, 2013, 11:03:46 AM
September 2013 draw at Nolimits-Lottery.com

Hi guys I would like to introduce a new bitcoin lottery - Nolimits-Lottery.com Where you can play daily, weekly and monthly draws.

So starting from this September we will have a monthly draw that should hopefully attract more people and pot size should be much bigger than in weekly and daily draws

The lottery is completely provably fair, we even have a script and API to check our fairness. You can read more in the main thread https://bitcointalk.org/index.php?topic=290975.0

Feel free to get in and good luck.
3  Economy / Gambling / Re: Nolimits-Lottery.com - Provably fair, DAILY WEEKLY MONHLY draws. NO FIXED price on: September 09, 2013, 02:10:58 PM
CHANGELOG:
  2013-09-10:
     Added instant results, you can see who is going to win the draw like if the draw would end right now.
  2013-09-09:
     If the current draw haven't received more than 5 participations before it have been closed, all participations of the current draw are moved to the next one.
4  Economy / Gambling / ▶Nolimits-Lottery.com - Provably fair, DAILY WEEKLY MONHLY draws. NO price limit on: September 09, 2013, 12:14:14 PM

Hi guys, I'd like to introduce a site I've been working on: Nolimits-Lottery.com

Features
  • no registration
  • no tickets
  • no price limit
  • instant results (kind of)
  • the more you send the higher your chances
  • 5 winners
  • daily, weekly, monthly draws
  • 2 confirmations
  • provably fair

Description
So, basically this is a lottery with unusual properties: it's completely anonymous, no registration required, it doesn't have tickets or number guessing, there is no limit to the amount of bitcoin you can send in the each draw and chances to win are proportional to the amount you've sent. So for example if the draw pool is currently 75 BTC and you've just sent 25 BTC, totalling the pool at 100 BTC, your chances to win will be 25%

Winners
There're 5 winners in each draw: 1st place winner takes 50% of the pool, second - 25%, third - 12.5%, forth - 6.75%, fifth - 3.125%, remaining amount is the house edge.

Draws
Currently there is DAILY, WEEKLY and MONTHLY draws, their names are self explanatory I think.

Provably fair
It is provably fair of course. We use a combination of server side seed and transactions hashes: a server side seed and is pregenerated for each draw and its hash published while the draw is active and when the draw ends we publish the original seed. We concatenate it with transaction hashes to generate an unpredictable number that is used to determine lottery winners, you can read more at the Fairness page
And we also have a python script that implements the algorithm and verifies results, you can inspect and run it, just give the draw id: python verify.py 25
Code:
#!/usr/bin/env python
# -*- coding: utf-8 -*-

from __future__ import print_function

import json
import requests
import sys

from hashlib import sha256

def make_draw(amounts, hash):
    hash_num = int(hash, 16)
    total = sum(amounts)
    total_bits = len(bin(total)) - 2
    rand_num = int(bin(hash_num)[-total_bits:], 2)
    offset = 0
    while rand_num > total:
        offset += 1
        rand_num ^= int(bin(hash_num)[-total_bits-offset:-offset], 2)

    i = lottery(amounts, rand_num)
    return i

def lottery(elements, rand):
    value = 0
    for i,el in enumerate(elements):
        value += el
        if rand <= value:
            return i

def prettify(dictionary):
    return json.dumps(dictionary, indent=4, sort_keys=True)

URL = 'http://nolimits-lottery.com/api/draw/' + sys.argv[1]

draw = requests.get(URL).json()

#print "DRAW: ", prettify(draw)

participations = sorted(draw['participations'], key=lambda p:p['amount'], reverse=True)
amounts = map(lambda p:p['amount'], participations)
combined_hash = sha256(reduce(lambda acc, p: acc + p['txid'], participations, draw['seed'])).hexdigest()

total = sum(amounts)
reward = total/2
fee = total * 0.03125
i=0
results = []
while reward >= fee:
    if not participations:
        if results: results[-1]['amount']+=total-fee
        break
    winner = make_draw(amounts, combined_hash)
    result = dict(
        participation_id=participations[winner]['id'],
        place=i+1,
        amount=reward
    )
    results.append(result)
    winning_participation = participations.pop(winner)
    amounts = map(lambda p:p['amount'], participations)
    total = reward
    reward = total/2
    combined_hash = sha256(combined_hash + winning_participation['txid']).hexdigest()
    i+=1

#print "RESULTS: ", prettify(results)

real_winners = sorted(draw['winners'], key=lambda p:p['place'], reverse=True)
expected_winners = sorted(results, key=lambda p:p['place'], reverse=True)

for i, winner in enumerate(real_winners):
    if not expected_winners[i]['participation_id'] == winner['participation_id']:
        print("VERIFICATION FAILED")
        exit(1)

print("RESULT VERIFIED")

Testnet
And you can test it out safely for free using testnet version http://testnet.nolimits-lottery.com/ just use some testnet faucet like http://testnet.mojocoin.com/ to get  free testnet bitcoins

Any feedback and suggestions are appreciated and welcomed.
Good luck to all.
5  Economy / Gambling / Re: TossBits.com - toss a coin like game with variable payout. Provably fair on: August 22, 2013, 09:15:39 PM
the more you lose the higher probability to win

Sounds like gambler's fallacy to me.
Smiley
Maybe I wasn't clear enough: it is not the probability of winning is higher - it is always 50% it is the chances to win you money back because you decrease the bank in geometric progression.
6  Economy / Gambling / Re: TossBits.com - toss a coin like game with variable payout. Provably fair on: August 22, 2013, 08:53:30 PM
another problem I see is that if a payout % is lower than 99% , why would I play at your site instead of just-dice for example that will always give me 99% return if I win?
Because it doesn't work like a dice game - that's the whole point, lets consider the following example:
We have a 1BTC bet, with the payout 50%, you may think that this is not a nice situation to get in the game, but actually you could have the following strategy
1. Ensure you have enough balance to make something like 5-6 bets (i.e. 5-6 BTC), lets say we have 5 btc
2. Start betting, if you have lost, bank will have 2 btc and payout will be 100% and you have 4 btc in balance
3. You can continue to bet, if you lost again you will have 3 btc in balance and bank will be 3btc and payout is 150%
4. As you can see bank and payout are heavily depend on the current streak if it is all loses - it will quickly grow, but if it all wins you can quickly recover all loses, and the more you lose the higher probability to win. Also bank grows in arithmetic progression and decreases in geometric.
5. Lets say you bet again and you win, you won 1.5 btc, your balance now is 4.5 btc and bank is 1.5 btc
6. You bet again and you won 0.75 btc and you balance will be 5.25 BTC - it is already higher than you had when you started!



So to sum up: in dice games it all about luck, here you can have some strategy, but because this is gambling no one guaranteeing that there is a strategy that will always make you money, for instance some dude could watch the site while you making these bets and he could just make a bet in between your bets and win.

And if this thing will take of, be sure it wouldn't be people who play it but bots. Lol, I was even thinking that I should take some time and release a bot at the same time with the game so that people will be equal in their chances Smiley But I already had a deadline for this thing a week ago, so I just had released it without any fancy bots Smiley
7  Economy / Gambling / Re: TossBits.com - toss a coin like game with variable payout. Provably fair on: August 22, 2013, 07:48:56 PM
The problem with this aproach, is that everytime I access your site I will have to check the code to see if you didn't change it. Will be way better if you implement a way for us to change it.
Yep. added to the todo.


The seed can't be global, but attached to the session. IMO, the best way to do it is to generate a seed to our session, show it to the user just before any bet, provide a way so we can set our client seed and after the bet generate another server seed to the next bet.

Okay, I'm gonna think on it.
8  Economy / Gambling / Re: TossBits.com - toss a coin like game with variable payout. Provably fair on: August 22, 2013, 05:34:46 PM
Why wouldn't it make sense to create a different server seed beforehand for each game and after it is used, immediately publish it?
Just wonder how will you check it? You decide to check our honesty - you check the client seed, remember it, you make a bet - and check what was the server seed - seems ok? But it isn't in this scenario we could just easily fool you by using any seed that will make any outcome we want - just enumerate few random seeds that would give us desired outcome. Even if we would somehow publish a hash of this seed - you cannot be sure that hash you see is for the seed that you will get when you bet, since any other player might use this seed before you.

But if a player uses that hash just before me, I could easily confirm this on the right side. Now you can say: doesn't prove anything since we could already do this.

Well with your current implementation you could also skip hashes from the batch and add fake bets to the right to compensate.
Sorry, but I don't follow what you trying to say - have you found any significant flaw in this scheme compared to to others or you suggesting an better solution? We can't skip hashes from the batch, because they are taken sequentially
9  Economy / Gambling / Re: TossBits.com - toss a coin like game with variable payout. Provably fair on: August 22, 2013, 04:00:16 PM
Why wouldn't it make sense to create a different server seed beforehand for each game and after it is used, immediately publish it?
Just wonder how will you check it? You decide to check our honesty - you check the client seed, remember it, you make a bet - and check what was the server seed - seems ok? But it isn't in this scenario we could just easily fool you by using any seed that will make any outcome we want - just enumerate few random seeds that would give us desired outcome. Even if we would somehow publish a hash of this seed - you cannot be sure that hash you see is for the seed that you will get when you bet, since any other player might use this seed before you.
10  Economy / Gambling / Re: TossBits.com - toss a coin like game with variable payout. Provably fair on: August 22, 2013, 03:43:28 PM
I first read it incorrectly and assumed the batch hash was the hash of the next server seed, which is not the case.

Why did you take this approach instead of just publishing the hash of the next seed?
Do you mean kind of the server seed that changes, say, once a day and its hash published somewhere on the site?
Well, with this I should also make sure that you cannot use client seed twice, since it will be obviously exploitable, so I just thought making unique random seed for each bet would be more secure, the problem was that publishing hash of this seed wouldn't make much sense because it would always change with each bet, so I decided to combine them in batches and publish the hash of the batch.
11  Economy / Gambling / Re: TossBits.com - toss a coin like game with variable payout. Provably fair on: August 22, 2013, 03:20:10 PM
do i have to make an account to use the test site?
Yep, but it doesn't check emails, so, you can use whatever email you want =)
You can also use testnet faucet to get the coins - http://testnet.mojocoin.com/
12  Economy / Gambling / TossBits.com - toss a coin like game with variable payout. Provably fair on: August 22, 2013, 02:54:00 PM
clickable: TossBits.com
testnet for those who want to try it safely: http://testnet.tossbits.com/

Hi guys, I've been working on a new gambling site, it is like a coin toss game, where your chances are 50%. But unlike other sites, I've made payout variable, basically, when you lose, your wager goes to the bank, and when you win you get 50% of the bank.

Some other features:
  • Low house edge: 1%
  • Provably fair
  • Off the chain transactions
  • Realtime
  • Chat

Gameplay:
We have fixed size bets: from 0.0005 to 1 BTC, that's because we have a bank for each bet type. As I've mentioned payouts are not fixed and depend on the result of the previous bets, if you lose, or other players lose, their wager goes to the bank, rising the available payout. If someone wins they get 50% of the current bank, so in theory it is unlikely that bank can be emptied. What that means for you as a player? You can choose your own strategy, for instance you can watch bets in realtime and play only when the payout is significant enough for you, or you if you have enough coins in you balance you can play agains the bank - because all coins you lose go to the bank a series of wins can recover all loses, so you playing until you leave the bank with less coins than were there when you started

Provability:
All results are provably fair. We use random client and server seeds to generate a hash that is used to determine luck, server side seeds grouped into batches by 1024, and we calculate a hash for a batch, therefore guaranteeing that we cannot alter the server seed without altering entire batch. Client side seeds generated after each bet - it is all embedded right into html and is not minified, so you can inspect the code.
Here also the python script that can check results:
Code:
# -*- coding: utf-8 -*-
from __future__ import print_function

import requests
import sys

from hashlib import sha256

URL = 'http://tossbits.com/api'

bet_id = sys.argv[1]
bet = requests.get(URL + '/bet/' + bet_id).json()
rand_hash = sha256(bet['server_seed']+bet['client_seed']).hexdigest()
luck = bool(int(bin(int(rand_hash, 16))[-1]))

print('Luck: ', luck)

batch = requests.get(URL + '/batch/'+bet['batch']).json()
if batch.get('error'):
    print("couldn't verify batch, because it is not exhausted yet")
    exit(1)

acc = ''
for hash in batch['hashes']:
    acc += hash

batch_hash = sha256(acc).hexdigest()
assert batch_hash == bet['batch']
You need to install `requests` library first. To run: `python verifybet.py <bet-id>`, for example python verifybet.py 34


I would like if you guys give it a try
Any feedback?

Thanks!
13  Economy / Service Announcements / Re: Predict Coins - Bitcoin price prediction game! on: May 20, 2013, 07:40:23 PM
Looks nice... but contrast is to low... man you should check http://contrastrebellion.com/
14  Local / Работа / Re: BTC-XRP шлюз on: May 18, 2013, 11:53:19 AM
Биткоиновские IOU можно менять на XRP прямо через саму рипплу, насколько я понимаю
15  Bitcoin / Project Development / Re: Yet Another Decentralized Exchange on: May 18, 2013, 10:53:39 AM
I would argue that the handling of fiat should be completely decoupled from any future exchange, P2P or otherwise.

We let dealers/brokers/banks/mtgox handle fiat. They can worry about regulations, AML compliance etc.

When we deposit $ with them, they give us a colored Bitcoin or an alt-chain coin that is backed by our deposit.

Once we have our MtGoxUSD coins, we can trade in real-time on the P2P crypto currency exchange. No waiting for bank transfers etc.

So perhaps efforts should be focused on creating an open source crypto-coin-only exchange. It does not even need to be P2P for it to be useful.

What you describing is already exist and called Ripple, just FYI
16  Alternate cryptocurrencies / Altcoin Discussion / Re: The DHS Can Seize All Your Ripple Balances With One Court Order on: May 16, 2013, 07:49:15 AM
Another question, if the devs for any of the other coins just gave up and quit tomorrow then somebody else could pick up where they left off (or not) and people would still have access to all their coins.

If the owners of Ripple.com decide to stop paying for their domain or web hosting, what happens to your thousands of XRPs...?
What if owners of Google.com decide to stop paying for their domain or web hosting?
17  Local / Трейдеры / Re: Где можно торговать в шорт другими валюта on: May 13, 2013, 01:22:19 PM
Отличный план!
18  Bitcoin / Development & Technical Discussion / Instant transactions without third parties by exchanging private keys on: May 07, 2013, 12:07:00 PM
Well, maybe this idea is already proposed but what if we could make instant (as instans as the speed of light in optical cables) transactions by exchanging private keys.

The idea is to made transaction with a number of outputs each with some little amount of bitcoins, for example a 10 outputs with $10 worth of bitcons each. And wait for its confirmation.

Then when you want to buy something that costs, say, $22.5 you give the merchant 3 outputs with the corresponding private keys, merchant ensures that these outputs indeed have $30 worth of bitcoins and have 6 or more confirms and then merchant creates a transaction that deposits $22.5 to his address and $7.5 to yours as a change.  You immediately can spot a scam if merchant doesn't issue a change transaction so in a face-to-face situations this might not be a problem. Simple and as instant as possible, no third parties, requires only some trust to the merchant, you can lower risks by making outputs with smaller amounts, like $1, $5 etc.
19  Bitcoin / Development & Technical Discussion / Re: Preventing double-spending attacks with semi-trusted 3rd parties on: April 30, 2013, 08:41:44 AM
The problems with this approach (if i understand correctly)
1. You still have to send bitcoins to this "M of N" address and so you still have to wait while this transaction get 6 confirmations.
2. What is incentive for the trusted auditors? You could send fees as an output in transaction, and if they see that tx includes fee they provide a signature, but tx would be huge, compared to standard tx
3. What to do in case of auditor closing its service, well, there is small chance that all auditors shutdown their services at once, but if you send bitcoins to this address and then want to use it after 2 years you may, to your surprise,  find that these auditors don't exists anymore.

However this is still much better than trusting to the one green address provider.
20  Alternate cryptocurrencies / Altcoin Discussion / Re: the disposable blockchain on: April 29, 2013, 07:08:56 AM
Why someone would create such chain? If it's for local spending, or for some entities with established relationship then why they would use it in a first place, why just don't use trusted third party (in the case if you trying to keep the blockchain more clean), no hashing, no mining, small fees, very simple.
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