Transparent Lottery

Generation of pseudo-random numbers from a public, verifiable algorithm using Bitcoin network hashes.

With this innovation, betting games, raffles, and prizes can benefit from the transparency of the draws, ensuring that there will be no manipulation of the results. With this algorithm, anyone can verify the operation, making the process transparent.

Number Drawing

For the generation of the drawn numbers, a drawing seed number is generated, which is unique for each Bitcoin block. As a Bitcoin block is generated, on average, every 10 minutes, a drawing can then be generated, on average, every 10 minutes.

When obtaining the block hash, which is a 256-bit hash, or 64 hexadecimal characters from 0 to F, we call it the drawing seed number. This number is converted to a base number, according to the betting possibilities of the desired game. As the mining difficulty increases, the difficulty of obtaining draws increases. According to the desired base, there can be up to 256 results.

Summarized Process:

1. Definition of the game base;
2. Definition of the block number;
3. Extraction of the drawing seed number;
4. Generation of the drawing roll number;
5. Generation of the drawing results.

Definition of the Game Base

Define the number of possibilities for each bet. This is the game base.

Example

For a 6-sided die, the game base is 6.

Definition of the Block Number

Define a block number with a value greater than the height of the last Bitcoin block, sufficient for all bets to be placed in a timely manner.

Extraction of the Drawing Seed Number

Obtain the hash of the block at the defined height, after the first validation, because players can make the extraction after the first validation. The extracted value must be a 256-bit hash (64 hexadecimal digits). This is the drawing seed number.

Example

For block 0, when checking the hash, we find the value below in hexadecimal. This is the drawing seed number.

000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f

Generation of Drawing Roll Number

After obtaining the drawing seed number, reprocess it using the SHA-256 algorithm. Each application of the algorithm produces a drawing roll number. Set the Roll value to determine which drawing roll number you want to generate. The Roll 0 is always equal to drawing seed number. The generator algorithm used must be public so that it can be publicly verified.

Example

For drawing seed number, the drawing roll number for each roll are:

• Seed Number:

    000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
  

• Rolls:

    Roll: 0
    Drawing Roll Number: 000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
  
    Roll: 1
    Drawing Roll Number: 7426ba0604c3f8682c7016b44673f85c5bd9da2fa6c1080810cf53ae320c9863
  
    Roll: 2
    Drawing Roll Number: ae253ca2a54debcac7ecf414f6734f48c56421a08bb59182ff9f39a6fffdb588
  
    Roll: 3
    Drawing Roll Number: 4f28a6114fe8b446cca837ff8481082a42eb286f8e91c2ac3d6f226b83e8cd5a
  

The generator algorithm is the Python function below.

import hashlib


def new_drawing_roll_number(drawing_roll_number: str):
    return hashlib.sha256(bytes.fromhex(drawing_roll_number)).hexdigest()

Generation of the Drawing Results

After obtaining the drawing roll number, convert it to the game base. The conversion algorithm used must be public so that it can be publicly verified.

Example

For the drawing seed number, roll, the drawing roll number is:

drawing seed number: 000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
roll: 0
drawing roll number: 000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
game base: 6
drawing results: 1, 3, 5, 2, 5, 2, 1, 2, 5, 2, 0, 1, 0, 1, 0, 2, 5, 2, 1, 2, 4, 2, 2, 1, 2, 2, 4, 2, 1, 2, 0, 0, 2, 0, 2, 4, 5, 5, 4, 4, 5, 1, 5, 0, 5, 4, 2, 0, 1, 0, 5, 4, 1, 5, 0, 3, 1, 0, 5, 0, 3, 5, 3, 1, 0, 3, 3, 3, 0, 1, 3, 1, 5, 2, 3, 4, 1, 4, 3, 2, 5, 4, 3.

The conversion algorithm is the Python function below.

def generate_drawing_numbers(self, seed: str, base: int) -> list[int]:
    seed = int.from_bytes(bytes.fromhex(seed.zfill(64)), byteorder="big")
    numbers = []
    while seed > 0:
        numbers.append(seed % base)
        seed //= base
    return list(reversed(numbers))

Bet Verification

The drawn number should only be considered valid if the block has 6 or more confirmations. It is not recommended to pay the prize before these confirmations. Each bet is managed by a betting system that this specification does not cover. The verification of a bet is done by verifying if each bettor managed to guess the drawn number.

Copyright (C) 2025 D. H. B. Marcos

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