data.cs

// generates a new hash for the block including the time stamp,
// the previous block has, the data and the nonce.
internal string GenerateBlockHash()
{
    SHA256 sha256 = SHA256.Create();

    byte[] bInput = 
        Encoding.ASCII.GetBytes($"{TimeStamp}-{PreviousBlockHash ?? ""}-{Data}-{Nonce}");
    byte[] bOutput = sha256.ComputeHash(bInput);

    return Convert.ToBase64String(bOutput);
}

// this method is generating hashes until a new hash with a specific
// number of leading zeros is created
public void Mine(int difficulty)
{
    string sLeadingZeros = new string('0', difficulty);

    while (this.BlockHash == null 
           || this.BlockHash.Substring(0, difficulty) != sLeadingZeros)
    {
        this.Nonce++;
        this.BlockHash = this.GenerateBlockHash();
    }
}