BetValidator.cs

byte[] StringToBytes(string s)
{
    return Enumerable
        .Range(0, s.Length / 2)
        .Select(x =>
        {
            // $"Converting Hex {s.Substring(x * 2, 2)} to Byte {byte.Parse(s.Substring(x * 2, 2), System.Globalization.NumberStyles.HexNumber)}".Dump();
            return byte.Parse(s.Substring(x * 2, 2), System.Globalization.NumberStyles.HexNumber);
        })
        .ToArray();
}

string BytesToString(byte[] ba)
{
    StringBuilder hex = new StringBuilder(ba.Length * 2);
    foreach (byte b in ba)
        hex.AppendFormat("{0:x2}", b);
    return hex.ToString();
}

// serverSeedHash - Given to clientBytes before bet
// clientSeed - generated by clientBytes before bet
// serverSecretSeed - appears in validation page (secret of serverSecretSeedBytes)
// betNumber - always 0
// betResult - the roll. 981774 = 98.1174 = a roll of 98/100

bool validateBetResult(string serverSecretSeed, int clientSeed, int betNumber, long betResult, string serverSeedHash = null)
{
    byte[] serverSecretSeedBytes = StringToBytes(serverSecretSeed);
    $"serverSecretSeed: {serverSecretSeed}".Dump(); serverSecretSeedBytes.Dump();

    byte[] clientBytes = BitConverter.GetBytes(clientSeed).Reverse().ToArray();
    $"clientBytes: {clientSeed}".Dump(); clientBytes.Dump();

    byte[] betNumberBytes = BitConverter.GetBytes(betNumber).Reverse().ToArray();
    $"betNumberBytes: {betNumber}".Dump(); betNumberBytes.Dump();

    byte[] serverSeedHashBytes = serverSeedHash == null ? null : StringToBytes(serverSeedHash);
    $"serverSeedHash: {serverSeedHash}".Dump(); serverSeedHashBytes.Dump();

    using (System.Security.Cryptography.SHA512 sha512 = new System.Security.Cryptography.SHA512Managed())
    {
        if (serverSeedHashBytes != null)
        {
            using (System.Security.Cryptography.SHA256 sha256 = new System.Security.Cryptography.SHA256Managed())
            {
                byte[] serverSecretSeedBytesHashed = sha256.ComputeHash(serverSecretSeedBytes);
                $"serverSecretSeedBytesHashed: {BytesToString(serverSecretSeedBytesHashed)}".Dump(); serverSecretSeedBytesHashed.Dump();
                $"serverSeedHash:              {serverSeedHash}".Dump();
                if (!serverSecretSeedBytesHashed.SequenceEqual(serverSeedHashBytes))
                {
                    "Server seed hash does not match serverSecretSeedBytes seed".Dump();
                    throw new Exception("Server seed hash does not match serverSecretSeedBytes seed");
                }
            }
        }

        byte[] data = serverSecretSeedBytes.Concat(clientBytes).Concat(betNumberBytes).ToArray();
        $"data: {BytesToString(data)}".Dump(); data.Dump();
        byte[] hash = sha512.ComputeHash(sha512.ComputeHash(data));
        $"hash: {BytesToString(hash)}".Dump(); hash.Dump();

        while (true)
        {
            for (int x = 0; x <= 61; x += 3)
            {
                $"{hash[x]} << 16 | ({hash[x + 1]} << 8) | {hash[x + 2]} = {(hash[x] << 16)} | {(hash[x + 1] << 8)} | {hash[x + 2]} = {(hash[x] << 16) | (hash[x + 1] << 8) | hash[x + 2]}".Dump();
                long result = (hash[x] << 16) | (hash[x + 1] << 8) | hash[x + 2];
                $"{x}: {result}".Dump();
                if (result < 16000000)
                    $"{result % 1000000} == {betResult}".Dump();
                return result % 1000000 == betResult;
            }
            hash = sha512.ComputeHash(hash);
        }
    }
}

validateBetResult("67381d32d0cf9114b96cf4103cdd69b25c9fd2f0c6780dce650c735753181a80", 734819011, 0, 994102, "3330633c2106b4b6a5a480dc2eabf43618fa172e5ec81e38da44318466fb84d6")
.Dump();