Add Mining/Proof-of-Work

BasicBlockChain/Block.cs

@@ -11,6 +11,7 @@ namespace BasicBlockChain
         public string PreviousHash { get; set; }
         public string Data { get; set; }
         public string Hash { get; set; }
+        public int Nonce { get; set; }
 
         public Block(DateTime date, Block previousBlock, string data)
         {
@@ -25,11 +26,21 @@ namespace BasicBlockChain
         {
             SHA256 sha256 = SHA256.Create();
 
-            byte[] dataBytes = Encoding.UTF8.GetBytes(string.Format("{0}-{1}-{2}", Date, PreviousHash, Data));
+            byte[] dataBytes = Encoding.UTF8.GetBytes(string.Format("{0}-{1}-{2}-{3}", Date, PreviousHash, Data, Nonce));
             byte[] hashBytes = sha256.ComputeHash(dataBytes);
 
             string hash = Convert.ToBase64String(hashBytes);
             return hash;
         }
+
+        public void Mine(int difficulty)
+        {
+            var leadingZeros = new string('0', difficulty);
+            while (Hash.Substring(0, difficulty) != leadingZeros)
+            {
+                Nonce++;
+                Hash = CalculateHash();
+            }
+        }
     }
 }

BasicBlockChain/BlockChain.cs

@@ -7,10 +7,13 @@ namespace BasicBlockChain
     public class BlockChain
     {
         public List<Block> Chain { get; } = new List<Block>();
+        public int Difficulty { get; set; } = 2;
 
-        public BlockChain(DateTime? genesisDate = null)
+        public BlockChain(DateTime? genesisDate = null, int difficulty = 2)
         {
             Block genesisBlock = new Block(genesisDate ?? DateTime.UtcNow, null, "{}");
+            genesisBlock.Mine(difficulty);
+            Difficulty = difficulty;
             Chain.Add(genesisBlock);
         }
 
@@ -18,6 +21,7 @@ namespace BasicBlockChain
         {
             Block lastBlock = Chain.Last();
             Block newBlock = new Block(date, lastBlock, data);
+            newBlock.Mine(Difficulty);
             Chain.Add(newBlock);
         }
 

BasicBlockChain/Program.cs

@@ -10,12 +10,15 @@ namespace BasicBlockChain
 
             // Example BlockChain with some example data
             Console.WriteLine();
-            Console.WriteLine("#### BlockChain with sample data");
+            Console.WriteLine("#### Mining BlockChain with sample data");
-            BlockChain nullCoin = new BlockChain(new DateTime(2000, 1, 1));
+            var startTime = DateTime.UtcNow;
+            BlockChain nullCoin = new BlockChain(genesisDate: new DateTime(2000, 1, 1), difficulty: 2);
             nullCoin.AddData(new DateTime(2000, 1, 2), "{ sender: VAR, receiver: NAM, amount: 10.00}");
             nullCoin.AddData(new DateTime(2000, 1, 3), "{ sender: NAM, receiver: VAR, amount: 5.00}");
             nullCoin.AddData(new DateTime(2000, 1, 4), "{ sender: NAM, receiver: VAR, amount: 5.00}");
             Console.WriteLine(jsonWriter.Write(nullCoin));
+            var endTime = DateTime.UtcNow;
+            Console.WriteLine($"Duration: {endTime - startTime}");
 
             // Verify
             Console.WriteLine("BlockChain is Valid? {0}", nullCoin.Verify() ? "True" : "False");