Program.cs

using System;
using System.Linq;

namespace SimpleBlockchain
{
    class MainClass
    {
        public static void Main(string[] args)
        {
            Random rnd = new Random(DateTime.UtcNow.Millisecond);
            IBlock genesis = new Block(new byte[] { 0x00, 0x00, 0x00, 0x00 });
            byte[] difficulty = new byte[] { 0x00, 0x00 };

            BlockChain chain = new BlockChain(difficulty, genesis);
            for (int i = 0; i < 200; i++)
            {
                var data = Enumerable.Range(0, 2256).Select(p => (byte)rnd.Next());
                chain.Add(new Block(data.ToArray()));
                Console.WriteLine(chain.LastOrDefault()?.ToString());

                Console.WriteLine($"Chain is Valid: {chain.IsValid()}");
            }

            Console.ReadLine();
        }
    }
}