“FREE BTC”

The “Free BTC” feature is like the Name says, you can Claim every 60 minutes Free Bitcoin and yes, you heard it right, it's totally free. So every hour you have the chance to hit the number 10000 and get 200$ worth of Bitcoin. If we look at this from the other side you should hit the number 10000 every 10000 times which means it can be your first or also your last Roll. You also receive a certain number of Lottery Tickets & Reward Points for every free Claim. Personally, I have made 4500 Claims so far and I got a 1-second prize already. The Freebitcoin Bitcointalk Topic of the biggest Wins proves every hater wrong since tons of people have gotten the number 10000 already. If you are one of those Winners you’ll get an extra 5$ in your Bitcoin Wallet if you post the proof of your Win on this Topic. Happy rolling!

“Golden Ticket”

This lottery is provably fair. What that means is that there is no way Freebitcoin can cheat you by picking a lottery winner who they favor. All winners are picked randomly and the method for picking the winners is described below.

1. At the beginning of each round, Freebitcoin generates a server seed for that round and shows everyone the SHA256 hash of this seed.
2. When a lottery round has concluded, Freebitcoin makes a list of all user ids and their lottery tickets and sorts it in ascending order of the user ids.
3. Freebitcoin then uses this list to assign ticket numbers for all tickets. For example, if user id 1 has 10 tickets and user id 2 has 20 tickets, then user id 1 will have ticket numbers 0 to 9 and user id 2 will have ticket numbers from 10 to 29. This is done for all users.
4. Then the list containing the user IDs, tickets held by each user, and their ticket numbers are published in a text file. This file also contains the total number of tickets issued in the round and the server Seed for that round.
5. An MD5 hash of this text file is calculated.
6. Then the current bitcoin block number is recorded and a block number that is 12 blocks into the future is decided on. The block hash of this future block is used as a "client seed" ie. a seed that Freebitcoin is not aware of when the list in step 4 has been published.
7. Then a tweet is made via the FreeBitcoins Twitter account (https://twitter.com/freebitco) containing the link to the file generated in step 4, the MD5 hash of the file, and the future bitcoin block number as determined in step 6. Since tweets cannot be edited, only deleted, this will provide a timestamp for when the list in step 4 was made, which can be compared to check that the bitcoin block determined in step 6 is in the future ie. we do not know the block hash of this block when the list is generated.
8. The winning ticket numbers will be calculated as described below:

• A string (STRING1) is created - "[SERVER SEED]:[BLOCK HASH]:[WINNING POSITION]".
• The SHA256 hash of STRING1 is calculated and the first 8 characters of this hash are taken (STRING2).
• STRING2 is converted to a decimal which gives us a number between 0 and 4,294,967,295 (NUM1).
• NUM1 is then multiplied by the (total number of tickets minus 1) and divided by 4,294,967,295 to get a number (NUM2) between 0 and the total number of tickets less than 1.
• NUM2 is then rounded off to the nearest whole number which is the winning ticket number.

HOW IS THE SYSTEM FAIR?

The system described above that is used for picking the winners is provably fair because it has multiple safeguards in place to ensure that winners are picked randomly and fairly.

1. Freebitcoin provides a SHA256 hash of the server seed when a lottery round starts. If FreeBitcoin changes the server seed at any time, the SHA256 hash of the new seed will not match the hash they provided earlier. After a round has ended and FreeBitcoin provides the server seed that will be used to pick winners, the hash of the seed they provide can be checked against the hash they provided originally and both should match.
2. Freebitcoin uses a future bitcoin block hash as the "client seed" ie. a seed that we do not know of. All bitcoin block hashes are unique and nobody knows what the block hash of a future block will be until the block has been mined.
3. Freebitcoin uses Twitter to publish the future bitcoin block number, the list of users and their ticket numbers, and the MD5 hash of the user list. It provides a timestamp to check if the block hash that Freebitcoin uses is indeed in the future. Since tweets cannot be edited, only deleted - if Freebitcoin deletes the tweet after the future block has been mined and publishes a new one, it would be easy to catch them cheating by comparing the timestamp of the tweet and that of the bitcoin block. The timestamp of the tweet should always be lesser than the timestamp of the bitcoin block whose hash is used as the client seed.
4. Freebitcoin provides an MD5 hash of the text file containing the list of users and their ticket numbers. If even a single character in the text file is changed after the MD5 hash in the tweet is published, the MD5 hash of the edited file will not match the MD5 hash provided in the tweet.