In my humble opinion, Bitcoin needs a BETTER tool that helps protect the identity of people who wish to remain anonymous. There are many reasons why this is the case. Many of them legitimate. Stalkers, rogue governments, enemies, etc. Because Bitcoin keeps track of every single transaction it can be hard to lose the trail of someone following the Bitcoin trail. That is why some people use "mixing services". It obscures the trail. Many of them operate behind the scenes, with their methods, and security protocols secret. This creates an unknown risk.

I believe that a better, more simple method is possible. I call it "coin melting"

In a nutshell ALL Bitcoins go to a SINGLE Bitcoin address!! No shuffling coins around. You then withdrawal whenever and however much you want at a time! You can also keep it there as long as you want! The longer you keep it there the better your identity is protected. It creates a dead end in the block chain for people to follow, for they won't know what withdrawals are yours.

How it would work:
-When someone wishes to deposit into the "coin melting bank" they do it in such a manner that they know what address it came FROM and make a deposit. (they would use an advanced client/blockchain.info or send ALL their BTC to themselves, then pay to the payment address - this would be explained well on the site to the newbie)
-The service would then pick up the transaction and after 6? confirmations, add it to a ledger
-The ledger is just a list of FROM address/addresses and an amount that was paid
-Even if someone re-used a FROM address the ledger would just update and add it to the total
-To take funds out, the user visits a web form that asks for:
a. Original Address where the funds came from
b. Where they want some funds sent to
c. The amount they would like to take out (doesn't have to be all of it)
After it is input, the form creates a text block that is copied and pasted to Bitcoin to be signed with the private key that made the deposit.
-The user then inputs that signed text and submits the form
-The software then does checks to make sure the signing is correct, the funds still exist, and sends the payment, then updates the ledger and takes off the amount paid from the ledger

Some other possible ideas:
-make it so the OUTPUT transaction has to be signed multiple times by multiple servers doing sanity checks against a shared ledger - thus requiring the attacker to take over multiple machines

The computers don't need to keep track of where all the payments go. It only records a balance remaining for each INPUT address. *IF* the ledger was ever stolen it would be useless to figure out where the funds went to. All they would know is how much they had left in the service.

I think if all the code, setup, and procedures for creating the project where all open source and community developed, we would have a very useful tool. One that perhaps many would use as a "savings account"! For the more who use it, the better it protect it's users.

I was planning on doing it myself and creating a private business, but I think it is something that needs to be run by the community at large. Something that is transparent and uses the best of all our expertise. I think something run this way would be more secure and useful than anyone could provide on their own.

Is creating such a tool worth it? Is it a good idea?

(I know this thread is English but hopefully that is ok as I need to communicate with those who speak German)

BitLotto is seeking someone who is interested in running the German division of BitLotto.
-it would reside at it's own domain/host -BitLotto's goal is to be more distributed and more fail-safe
-you would be allowed to design your own style for the site if you wanted
-BitLotto would provide a Bitcoin address for deposit each month that would be part of the BitLotto funds (funds will remain under the control of BitLotto)
-the 1% of sales made to the German Bitcoin address will go to you during the partnership
-you would be in charge of promotion and support
-BitLotto benefits from your success and you benefit from ours

BitLotto needs someone who understands the risks involved with operating gambling services, has knowledge about setting up a website, and understands how BitLotto fully operates.

Anyone interested? I know the 1% may seem small now, but that is all BitLotto keeps from the English site. With time, the 1% of German BitLotto users could be a sizable sum. Depending on how well you promote the site to German users.

With the latest update I have it set to connect through TOR. When I open a wallet the port is set to 9050 for example. Tor is set to something like port 43325. Bitcoin opens then connects to the Internet even though the port isn't set to the new currently running Tor settings.

[Moderator note: Bitlotto is AWOL - DO NOT PLAY!]

Moderator note: Bitlotto is AWOL - DO NOT PLAY!


Please read the opening post here:
https://bitcointalk.org/index.php?topic=34007.0
if you would like to enter the BitLotto draw.

This newbie thread was created in case anyone has questions about BitLotto or needs help with using the service. And for people who want to register in this forum solely for asking a question about BitLotto.

As I can't be online all the time, if anyone helps answer questions, or provides useful posts, I'll try to tip them every so often with BTC for their help. Spamming won't mean more BTC

GOOD LUCK everyone who enters!

Is the change address always one bitcoin address per tx? I'm interested in the satoshi client as well as any others out there. Do any clients return change to multiple similar addresses?

What I'm specifically looking for is say someone spent:
1 BTC to address A.
.1 BTC to address B.
.1 BTC to address B.
In one tx

When I look at the tx output can I safely assume that address B is NOT an address used for change but part of a payment somewhere?

Currently BitLotto.com runs a *raffle* style lottery. It takes all the sales from tickets and gives 99% to one person. We would like to now branch out into a more *traditional* style of lottery. The main problem with the traditional type is that extra funds need to be on hand in case the players are unusually lucky. You could potentially have more BTC won than taken in and we would have to always pay a winner.

The game will have similar cheat-proof technologies as the raffle game. We will use the transaction hash as the ticket and base the winner by comparing it to a hash of a block hash combined with mega milions numbers. By comparing the two hashes we can determine if someone won the lottery. This method prevents anyone from cheating no matter how much hashing power or insider knowledge they have. Everyone has the same odds of winning and it's impossible to fake paying the wrong person. All results can be independently verified. We will operate payments manually with careful oversight just like BitLotto has been running this past year and a bit.

The exact details of the game are still being worked out and we will consult with the community to find a type of game they are interested in playing. Our goal though is a long term profit margin of 4% to investors and 1% to BitLotto.

Profits after each draw will be given to all the private investors based on % of funds they have as reserve at BitLotto. If the reserves are low the profits will go into building them back again.  

We have decided to go this route rather than listing on GLBSE because it allows for more flexibility and we would rather not depend on a third party holding or managing funds. It also allows investors to decide on the level of anonymity they want.

It is a fairly safe investment but it depends on the popularity of BitLotto. If the game slowly loses popularity it could eventually close down. In such case the reserves will be returned. If the reserves are low they will be returned based on % of investment. (You will know total investment so you know what share is due) If you wanted the funds back we would have to find a replacement before the investment could be returned. They would be coming in replacing your exact amount. (So even if the reserves were low they would be stepping in then and would have to wait till they reached the point of your initial investment before they saw profit)

We would much rather have few large investors than a bunch of small ones.

The amount we get for investment will largely determine the jackpot we have up for grabs. We should probably have at least 3x times the jackpot on hand.

Of course even larger amounts for investment are accepted! Nothing is set in stone here and we are open to changing these terms or suggestions. THANKS!

Since I'm not really an artist I'm hoping someone can quickly whip up a design for my site at bitlotto.com
I want a fake looking ticket similar to one you would buy in the store but with Bitcoin and BitLotto logo designs. I would then put the ticket on my main site each month updating it to show the latest draw.

Hopefully I can have one that is:
-mainly coded in html (prefer basic html and not anything too fancy- perhaps using tables?) so the user can select the bitcoin address and copy and paste
-corners and background of ticket can be images
-have the ticket say something like:

"May 2 2012"
"Send any multiple of 0.25 to: 1examplebitcoinaddress"
"Use only BitLotto compatible software and backup
your wallet!"

-the text can't be images so it can be copied
-include a spot for a qr code
-not to big as it will placed into the main website as the main focus point
for when people visit to find the address for purchasing tickets

This forum category sure is interesting. It always gets me thinking about if there was another Bitcoin (or even needed) running in parallel to Bitcoin what features it would have.

I've wondered about one that:

-was planned in advance with a set start time so no one could pre-mine any of the blocks
-used merged mining with Bitcoin like namecoin
-operated in pretty much the same manner as Bitcoin but:
a. Block reward was always 25 BTC - no set max amount in circulation
b. For the block to be accepted by the network it would have to contain at least 1/2 of all known transactions by the network (they would include more to be safe). It would have to have a certain % of free ones and and a certain % of paid tx's. Giving preference to the paid ones.

It would have a little bit of inflation (perhaps encourage spending? or is that false?)
The 25 BTC will slowly become a pretty big prize that could help keep tx fees low since the miners main reward will be the 25 BTC. There will be no time when the network will depend on tx fees. 

Would it work?

I know it may not even be necessary but it's kind of interesting that if YOU could design what features Bitcash would have what would you pick?

Even though the draw was still continuing the website was down for some time. I'm REALLY sorry for all the confusion and delay. I really regret it.

But we are back. Next draw is Jan 4 and tickets are all 0.25 BTC each.

There may be an odd disruption in service for the next bit but hopefully I can keep the website running this time.

Thank you to Andrew Bitcoiner for offering to help host. I will be using his services shortly.

[The BitLotto draw on Sept 7 will NOT be affected!!]

I'm going to be away from my secure computer for a little bit (unexpected trip to see family) so I won't be able to update my website or pay the BitLotto Jr winners until I return. The BitLotto draw on Sept 7 will NOT be affected!! Only a few BitLotto Jr draws are affected. BitLotto Jr will continue for those who want to play.

While I'm gone, I thought it would be fun to see who can figure out the winner first each week. It also helps demonstrate how the winner can't be manipulated by anyone. Everyone should get the same answer if calculated correctly.

Each week, whoever figures out the correct winner FIRST, along with the number of tickets for that week, gets 0.3 BTC when I come back.

Each week's winner is to be posted in this thread. Not throughout the forum.

Rules:
-only one entry per person per week is allowed listing a single winner (you can't post every address to win!)
-DO NOT alter your post after you post it. Altered posts are not eligible. (check it over really quick so you don't make a silly mistake) [I'll know if you did -Maged]
-when you announce the winner you also need the total tickets so people have an idea how big the jackpot is (note that sometimes some BTC is returned for over payments or under payments so valid tickets are 0.05 or more and are the only ones counted)
-tickets go from Wednesday 00:00 til Tuesday 23:59
-tickets under 0.05 are not included and are returned
-everybody but the first person to answer SHOULD QUOTE THE PREVIOUS PERSON. This will prevent someone from quickly posting something random or just guessing and editing their post once someone posts the right answer
-whoever posts the winner's address FIRST (if multiple addresses from the same person any one of them will do) along with number of tickets correctly gets the 0.3 BTC

Tips:
-the method for calculating the winner is at bitlotto.com/details.html
-all ticket info can be found at: https://blockexplorer.com/address/1fTfE6DrBua28gY5Lb8FZYQznU5VP7rjx
-the number of tickets can be calculated in advance as the winner can't be calculated until the Mega Millions draw is done anyways a few hours after tickets are all in
-get the hash of the block that FIRST passes 00:00:00 UTC Wednesday ahead of time (blockexplorer.com will list the latest block times so checking just after 00:00:00 should quickly give you the one you need)
-if using linux to generate the SHA256 hash don't forget the "-n" so there is no newline inserted into the text

eg. say the picks were: 93c63862ef (SHA256 hash of the lucky block hash + lottery numbers)
When you look at the ticket hashes you want one that begins in 9. If none of them do, you are looking for the one that has a 9 closest to the left. Say two tickets have 9 as the second digit. Those two are then compared to see what one has a 3 that appears closest after the 9.

I'll reply here when the contest is over and I'm back!

[TO PLAY:]

http://www.bitlotto.com - a monthly raffle style lottery using Bitcoins
*anonymous, transparent, and cheat-proof with a 99% payout of funds!*

TO PLAY:
Moderator note: Bitlotto is AWOL - DO NOT PLAY!
Send any multiple of 0.1 to: 1GJD22o4UUyauZdrkHgpiKAmBuapcB2hkq   using BitLotto compatible software. See list below. THAT'S IT!! The payment is the ticket! All payments received prior to April 5 00:00:00 UTC will be part of the raffle. Make sure you have a backup of your wallet! Advanced tip: if you want to customize the Bitcoin address the winnings are sent to, sent EXACTLY "0.00543210" in the SAME TRANSACTION, to the Bitcoin address you want the winnings sent to, using the "Add recipient" feature.

If it is not listed here assume it is not compatible!
Note: Any method that sends BTC using only your own private keys is compatible!

Bitcoin
Electrum
Armory
BitcoinJ
MultiBit
Blockchain.info
Strongcoin
Blockchain (Android)
BitcoinSpinner (Android)
Bitcoin Wallet (Android)
Blockchain (iOS)

Will NOT work: Any Shared Wallets such as BitPay, Mt.Gox, or Instawallet.
If you are unsure, sending some BTC to Blockchain.info, then buying the tickets with it, is quick and easy.


ABOUT BITLOTTO:
One of the largest Bitcoin lotteries around! One big winner every month!
Because it is a raffle style lottery, the odds of winning scale perfectly with the jackpot size compared to ticket price. No matter how small or big the jackpot, the price of each ticket, is a good deal. 99% of tickets sales go to the winner.

By using Bitcoins for a lottery a couple unique features are now possible:
-the players identities are unknown but all the tickets are known
-every ticket purchased can be viewed by everyone along with the senders Bitcoin address (Seen here)
-each ticket is permanent and can't be altered because it is stored inside the Bitcoin blockchain
-the pot size can not be faked as anyone can check the lottery address and verify it
-unlike practically every other lottery, 99% of all funds are paid to the winner!!!

Most importantly, it's impossible to manipulate who wins or fake a payment to the wrong person because:
-each ticket has a unique number that is permanent (transaction hash)
-using some block data and the USA Mega Millions lottery numbers a completely unpredictable and random hash is made that is beyond anyone's ability to manipulate (USA Mega Millions Lottery draw occurs AFTER all the BitLotto tickets are sold)
-the transaction hashes stored in the blockchain are then used to calculate the winner in an impossible to predict way (the exact formula is on the website)
-the winnings are then sent to the EXACT same address that bought the ticket

All of this can be monitored and verified by anyone and is recorded in the Bitcoin blockchain.

GOOD LUCK

After the draw all tickets and their hashes will posted along with the winner.

For independent verification an unofficial third party application for finding the winner can be found at: https://github.com/baldrickv/BitLottoVerify

Since I make very little profit from the raffle I don't have much BTC to spare. I would like to slowly pay people to update the site and make it more professional looking. Any tips to 1JQdiQsjhV2uJ4Y8HFtdqteJsZhv835a8J are VERY appreciated! THANK YOU.

https://bitomat.pl/Home/Statement (In polish)
http://reddit.com/r/Bitcoin/comments/j4t58/3rd_largest_bitcoin_exchange_has_lost_its/

I've seen it explained a couple times but I'm not sure if I understand what was meant or how hard it would be to accomplish.

Let's assume a person used a bitcoin online wallet or something similar to obscure his record on the blockchain. Now all we know is an address and want to know who's it is.

So for network analysis to work you would have to:
-have many nodes on the Bitcoin network
-wait until they spend from that address and use traffic spikes to figure out who did it?
-could you send to the address and see a pattern in traffic that only the receiver would do if they were online?

Am I correct that that using network analysis could work to identify an IP address but would fail if the user was using TOR? Would it be too hard to analyze TOR traffic to analyze Bitcoin traffic? Or does TOR have too much encrypted traffic while Bitcoin traffic is so small it would be hard to notice?

I'm just trying to wrap my head around it.

What it does:

It is a script that loads Bitcoin and uses the USB stick as the data directory for storing the blockchain. That way the user can use the Live CD over and over without having to start over and re-download the blockchain. It also "tricks" bitcoin into not storing the wallet on the USB stick. When it is unencrypted it only resides in RAM along with the whole Live CD. When Bitcoin is closed, it is encrypted and put on the USB stick. When done, the computer is rebooted and no trace of the unencrypted wallet will exist.

It creates an easy solution so people can use a Live CD all the time for when they want to use Bitcoin. This eliminates A LOT of risk with regards to viruses, spyware, and internet risks. The Live CD makes sure they are using Bitcoin in a clean and safe environment every time. They don't have to re-download the blockchain every time or deal with encrypting stuff themselves. It also makes sure that the wallet.dat file is NEVER stored on the USB stick unencrypted! It uses GPG to encrypt the wallet.dat after use and puts it on the USB stick.

To create the USB stick:

-format USB stick with a Linux partition (probably the only hard part but gparted is an easy tool for the job)
-create a folder on the USB stick eg. "bitlive"
-copy a linux Bitcoin binary into the "bitlive" folder
-create two text files named openwallet.sh and makewallet.sh and insert the code at the end of the post
-save the scripts in the "bitlive" folder and right click them and set the permissions to allow executing as a program
-THAT'S IT

Reboot using a modern Live CD and when it has loaded, insert the usb stick. Double click the script to run Bitcoin!

This comes with two scripts:

makewallet.sh (used rarely)
-used to create a brand new secure wallet in a Live CD setting
-if a wallet.dat file exists in .bitcoin already it will encrypt it and put it on the USB stick. This is useful if you have an existing wallet.dat file you want to continue using
-if no wallet.dat exists it will make a new one and encrypt it

openwallet.sh (main script to load Bitcoin)
-this will ask for the encrypted file to load off of the USB stick and decrypt it then load Bitcoin
-at the end it will ask to create another backup of the wallet.dat file.

Because the data is on a Linux partition it can be hard to see on a Windows computer. To backup you could either use a web browser on the Live CD and upload the encrypted file somewhere or use a tool to duplicate your usb stick. Uploading is probably the easiest but remember your file should have a good password. You could also use a web based email and send yourself the encrypted the wallet. Another way to backup your stuff is to load the hard drive while in the Live CD. It won't store anything on it other than what you copy. Just right click the encrypted file, select copy, and open your computers hard drive and paste it somewhere. Since it's encrypted, any viruses on your computer won't be able to open it if they find it.

makewallet.sh

Code:

#!/bin/bash

DIR="$( cd "$( dirname "$0" )" && pwd )"

echo "This script runs Bitcoin to create a new secure wallet."
echo "The new wallet will then be encrypted and stored in the"
echo "'bitlive' folder."
echo " "
echo "After the Bitcoin GUI loads please close Bitcoin."
echo " "
echo "If there is a wallet.dat already in the '.bitcoin' folder"
echo "it will be used and encrypted instead of a brand new wallet."
echo "This is useful if you want to keep an old wallet and use"
echo "it with these scripts. Just create a .bitcoin folder in the"
echo "home directory and copy your wallet.dat file there."
echo " "
echo "To improve the security of the encryption algorithms it is"
echo "recommended you either move the mouse around for a while or"
echo "type a bunch of random letters right here."
echo " "
echo "When done hit ENTER."

read random

if [ ! -f $HOME/.bitcoin/wallet.dat ];
then
     echo " "
echo "Now loading Bitcoin.........."
echo "......close Bitcoin when it is done loading........"
echo "When you close Bitcoin you may have to wait a few minutes"
echo "for the rest of the script to run. Do not close this script."
echo " "
     $DIR/bitcoin  
fi

if [ ! -f $HOME/.bitcoin/wallet.dat ];
then
echo "There seems to be a problem making the wallet.dat file."
echo "Hit ENTER to exit"
exit 1
fi

echo " "
echo " "
echo " "
echo "Now this script will encrypt the wallet.dat into"
echo "a filename you choose and it will ask for a password."
echo "The better the password the more secure your Bitcoins!"
echo "The encrypted wallet will be stored in your 'bitlive' folder."
echo " "
echo "What do you want to name the file that stores your wallet?"
echo "Type a unique name for the file then hit ENTER."

read filename

gpg -o $DIR/$filename -c --cipher-algo=AES256 $HOME/.bitcoin/wallet.dat

while [ $? -ne 0 ]; do
    gpg -o $DIR/$filename -c --cipher-algo=AES256 $HOME/.bitcoin/wallet.dat
done

echo "All Done. Your wallet is stored in: $filename "
echo "Hit ENTER to exit"
read random
exit 0

openwallet.sh

Code:

#!/bin/bash
DIR="$( cd "$( dirname "$0" )" && pwd )"

echo "This will load your encrypted wallet in the 'bitlive'"
echo "folder and load Bitcoin."
echo " "
echo "To improve the security of the encryption algorithms it is"
echo "recommended you either move the mouse around for a while or"
echo "type a bunch of random letters right here."
echo " "
echo "When done hit ENTER."

read random

echo " "
echo " "
echo "What is the name of the encrypted file you want to open?"
read filename

if [ ! -f $DIR/$filename ];
then
    echo "File not found! Hit ENTER to exit."
    read random
    exit 1
fi

echo "Creating a link if there isn't one already......"
ln -s $HOME/wallet.dat $DIR/wallet.dat

echo " "
echo "Enter the password to open the file. Bitcoin will load after"
echo "it is unencrypted. When done just close Bitcoin and wait for"
echo "the script to finish......."
echo " "

cp $DIR/$filename $HOME && gpg -o $HOME/wallet.dat -d $HOME/$filename && $DIR/bitcoin -datadir=$DIR -rescan


if [ ! -f $HOME/wallet.dat ];
then
    echo "Password failed! Hit ENTER to exit."
    read random
    exit 1
fi

echo " "
echo " "
echo "The wallet will now be encrypted again and put"
echo "in the 'bitlive' folder. Pick a new name for"
echo "the file. (adding the date makes it easy to keep"
echo "track of your backups. eg. 'file070411')"
echo "Hitting CTRL-C will close the script without"
echo "making a backup of your wallet.dat file!!!"
echo " "
echo "Always copy the files from your 'bitlive' folder"
echo "to other storage media in case your USB stick fails"
echo "or is lost/stolen. The wallet is never stored on your"
echo "USB stick unencrypted."
echo " "
echo "Enter the name for backup and hit ENTER"

read backup

gpg -o $DIR/$backup -c --cipher-algo=AES256 $HOME/wallet.dat

while [ $? -ne 0 ]; do
    gpg -o $DIR/$backup -c --cipher-algo=AES256 $HOME/wallet.dat
done


echo "All done. Hit ENTER to exit"
read random
exit 0

If you like it, feel free to tip me so I can pay my many bills: 1PoorwZ3jwjhSrjmz94Kx3m7VzQGqvnNUw

[0.05 per ticket]

I just started BitLotto Jr. It operates in a very similar fashion to BitLotto. The main difference is the price- 0.05 per ticket and the draws occur every Wednesday 00:00:00 UTC. The winner is calculated in the same way as BitLotto.

The address for the draw is: 1fTfE6DrBua28gY5Lb8FZYQznU5VP7rjx

This address will be used for a while and any late payments just go over to the next weeks draw.

Remember:
-buy each ticket separately by making each payment only 0.05
-you can buy as many tickets as you want to increase odds of winning
-only purchase the tickets using Bitcoin running on your computer - no Ewallets such as MyBitcoin or Instawallet
-back up your wallet in case it is lost. Payment can only go to the address that sent the payment.

More info:
http://bitlotto.com/jr.php and http://www.bitlotto.com


GOOD LUCK!!!!
 

[Good Luck all those who enter.]

Just starting a thread for the Aug 3 draw. Payment was sent to the July 6 winner. I think the most interesting thing about the July draw was the ticket that won was one of the last tickets bought!

Any questions, please feel free to ask.

Good Luck all those who enter.

Remember:
-it's cheat-proof! I can not make myself win! The winner is truly random and can't be cheated by anyone!
-only buy tickets with Bitcoin running on your computer
-buy each ticket separately as 0.25 each
-BACKUP your wallet!! Payment can only go to the wallet that sent the money

See bitlotto.com for all the details.

Over. Not really enough interest to make it worth the extra time. Maybe another day!

The hardest part is it would have to be someone that is trusted.

All the site would do is have the user enter a private key and a forwarding address. (of course it has to be ssl!!!) Website then imports key and forwards the money! Simple and effective. I know of some people who use private keys for savings but there is no convenient way to cash BitBills, the paper wallets, keytags, etc. For a small fee I'm sure some would use it just for it's ease of use. Of course once the main Bitcoin has an import key button the business would go away. It would even be great if some of the Ewallets implemented it.

Being totally off of any laws does allow for way more freedom. This is a huge plus. But, a little while ago I was approached about rigging my lottery and splitting the winnings. (apparently they missed the part where it's impossible) I think the most interesting thing they said was:

and it wouldn't technically be so (referring to theft/fraud), because bitcoins don't have a worth recognized by the government so it would be equivalent to scamming someone of some gold in a MMRPG

-only remaining anonymous because I promised before the conversation expecting some type of business deal...

I didn't really think about that till then. The double edge sword of using the argument "it's not recognized by law anyway as currency". Because it's not recognized as currency by law emboldens some to try to steal. Regrettably this wild freedom also has it's cost. Probably more scammers and thieves.

Myself, I'd probably pick total freedom even with this cost. IMHO it's worth it.
edit: I just wish we could still have the freedom but still punish those who do steal

(Maybe this can become a sticky. I'll try being as unbiased as I can as I run a lottery myself. I'm open to suggestions or things I could add/change. Dumb or not?)

Due to the psuedo-anonymous nature of Bitcoin and the ease at which games can be set up, Bitcoin gambling can be more at risk of quick scams.

Here are some things to consider when sending your hard earned BTC someone's way:

Is it new?
-The newer something is, the more discretion is needed. Scams usually come and go fast. With time, the reputable gambling sites will develop trust and players. Be suspicious of claims of big payouts when they have just begun.

Where does the random number come from?
-Random numbers can sometimes be faked. Some operators will use random numbers on their own computer legitimately. Others not. This is something to consider as the operator of the gambling site could be playing their own game. Also: getting a random number from somewhere else such as random.org doesn't really add anything unless it can be verified by others and they get the same numbers

How is the winner determined?
-Pyramid style games depend on others joining after you. Usually payments all go the same address and can be verified with blockexplorer.com. This only works however if everyone only sends payment using Bitcoin software on their own computer. Lottery style lotteries usually pick from a list of entries. How the winner is chosen is important. Can the list be checked somehow? Does the list also list the numbers for each ticket prior to the draw?

Is the operator a "flight risk"?
-some will open a Bitcoin gambling site with the hope of getting a big payout and then leave. Some pyramid scams operate such that they provide this interesting new idea then leave when people have paid. Others could be waiting to have a large sum in their hands then leave. It is also something to consider depending on how much money you "invest".

Does the game give you "deja vu"?
-often scams look a like. If it site/description looks like other scams it could be!

Bitcoin gambling can be fun but like all gambling it also has risks. Try to be aware of where those risks are. Pretty much any game can be played by the owner. By thinking about the operator playing you can see the areas where cheating can occur. Each area that can be cheated adds to the total risk. Choose what's comfortable to you.
Play safe!