M_Layashree_Assignment

M_Layashree_Assignment/HugoByte Full Code.txt

@@ -0,0 +1,132 @@
+import java.util.List;
+import java.util.LinkedList;
+import java.security.NoSuchAlgorithmException;
+import java.security.MessageDigest;
+
+class Block 
+{
+    private List<String> transactions;
+    private String previousHash;
+    private String hash;
+
+    public Block(List<String> transactions, String previousHash) 
+    {
+        this.transactions = transactions;
+        this.previousHash = previousHash;
+        this.hash = computeHash();
+    }
+
+    public String computeHash()
+    {
+        try 
+        {
+            MessageDigest md = MessageDigest.getInstance("SHA-256");
+            String data = transactions.toString() + previousHash;
+            byte[] hashBytes = md.digest(data.getBytes());
+            StringBuilder hexString = new StringBuilder();
+
+            for (byte hashByte : hashBytes) 
+            {
+                String hexDecimal = Integer.toHexString(0xff & hashByte);
+                if (hexDecimal.length() == 1)
+                {
+                	hexString.append('0');
+                }
+                hexString.append(hexDecimal);
+            }
+            return hexString.toString();
+        }
+        catch (NoSuchAlgorithmException e)
+        {
+            e.printStackTrace();
+            return null;
+        }
+    }
+
+    public String getHash() 
+    {
+        return hash;
+    }
+
+    public String getPreviousHash()
+    {
+        return previousHash;
+    }
+
+    public List<String> getTransactions()
+    {
+        return transactions;
+    }
+}
+
+class Blockchain 
+{
+    private List<Block> chain;                                        
+
+    public Blockchain()                                          		// Executed when a new Blockchain object is created.
+    {
+        chain = new LinkedList<>();                                 
+        chain.add(createGenesisBlock());                            
+	/* The createGenesisBlock() method is called to generate the first block (also known as the "genesis block"), which contains an 	empty list of transactions and a previous hash value of "0". This block is then added to the chain. */
+    }
+
+    private Block createGenesisBlock()   //Create and return the genesis block. This block serves as the starting point of the blockchain.
+    {
+        return new Block(new LinkedList<>(), "0");
+    }
+
+    // Adds a new block to the chain. It takes a list of transactions as input.
+    public void addBlock(List<String> transactions)                           
+    {
+        String previousHash = chain.get(chain.size() - 1).getHash();          // Retrieves the hash of the last block in the chain.
+        Block newBlock = new Block(transactions, previousHash);               
+        chain.add(newBlock);                                                  // The new block is added to the chain.
+        //System.out.println(newBlock.getHash());
+    }
+
+    public boolean validate() 
+    {
+        for (int i = 1; i < chain.size(); i++) 
+        {
+            Block currentBlock = chain.get(i);
+            Block previousBlock = chain.get(i - 1);
+
+            if (!currentBlock.getHash().equals(currentBlock.computeHash())) 
+            {
+                System.out.println("Sorry! Block hash does not match its content.");
+                return false;
+            }
+
+            if (!currentBlock.getPreviousHash().equals(previousBlock.getHash()))
+            {
+                System.out.println("Oops! Chain is Broken.");
+                return false;
+            }
+        }
+        System.out.println("Great! Blockchain is Valid.");
+        return true;
+    }
+}
+
+public class HugoByte
+{
+    public static void main(String[] args)
+    {
+        // Create a blockchain
+        Blockchain b = new Blockchain();
+
+        // Add some transactions to test the chain
+        List<String> transactions1 = new LinkedList<>();
+        transactions1.add("Alice sent Rs 100 as her savings to Bob.");
+        transactions1.add("Bob invested Alice's Rs 100 in Mutual Funds.");
+        b.addBlock(transactions1);
+
+        List<String> transactions2 = new LinkedList<>();
+        transactions2.add("Bob got Rs 150 back as Returns from Mutual Funds.");
+        transactions2.add("Bob returned Rs 100 back to Alice retaining the profit he got.");
+        b.addBlock(transactions2);
+
+        // Validate the blockchain
+        b.validate();
+    }
+}

M_Layashree_Assignment/HugoByte.java

@@ -0,0 +1,132 @@
+import java.util.List;
+import java.util.LinkedList;
+import java.security.NoSuchAlgorithmException;
+import java.security.MessageDigest;
+
+class Block 
+{
+    private List<String> transactions;
+    private String previousHash;
+    private String hash;
+
+    public Block(List<String> transactions, String previousHash) 
+    {
+        this.transactions = transactions;
+        this.previousHash = previousHash;
+        this.hash = computeHash();
+    }
+
+    public String computeHash()
+    {
+        try 
+        {
+            MessageDigest md = MessageDigest.getInstance("SHA-256");
+            String data = transactions.toString() + previousHash;
+            byte[] hashBytes = md.digest(data.getBytes());
+            StringBuilder hexString = new StringBuilder();
+
+            for (byte hashByte : hashBytes) 
+            {
+                String hexDecimal = Integer.toHexString(0xff & hashByte);
+                if (hexDecimal.length() == 1)
+                {
+                	hexString.append('0');
+                }
+                hexString.append(hexDecimal);
+            }
+            return hexString.toString();
+        }
+        catch (NoSuchAlgorithmException e)
+        {
+            e.printStackTrace();
+            return null;
+        }
+    }
+
+    public String getHash() 
+    {
+        return hash;
+    }
+
+    public String getPreviousHash()
+    {
+        return previousHash;
+    }
+
+    public List<String> getTransactions()
+    {
+        return transactions;
+    }
+}
+
+class Blockchain 
+{
+    private List<Block> chain;                                        
+
+    public Blockchain()                                          		// Executed when a new Blockchain object is created.
+    {
+        chain = new LinkedList<>();                                 
+        chain.add(createGenesisBlock());                            
+	/* The createGenesisBlock() method is called to generate the first block (also known as the "genesis block"), which contains an 	empty list of transactions and a previous hash value of "0". This block is then added to the chain. */
+    }
+
+    private Block createGenesisBlock()   //Create and return the genesis block. This block serves as the starting point of the blockchain.
+    {
+        return new Block(new LinkedList<>(), "0");
+    }
+
+    // Adds a new block to the chain. It takes a list of transactions as input.
+    public void addBlock(List<String> transactions)                           
+    {
+        String previousHash = chain.get(chain.size() - 1).getHash();          // Retrieves the hash of the last block in the chain.
+        Block newBlock = new Block(transactions, previousHash);               
+        chain.add(newBlock);                                                  // The new block is added to the chain.
+        //System.out.println(newBlock.getHash());
+    }
+
+    public boolean validate() 
+    {
+        for (int i = 1; i < chain.size(); i++) 
+        {
+            Block currentBlock = chain.get(i);
+            Block previousBlock = chain.get(i - 1);
+
+            if (!currentBlock.getHash().equals(currentBlock.computeHash())) 
+            {
+                System.out.println("Sorry! Block hash does not match its content.");
+                return false;
+            }
+
+            if (!currentBlock.getPreviousHash().equals(previousBlock.getHash()))
+            {
+                System.out.println("Oops! Chain is Broken.");
+                return false;
+            }
+        }
+        System.out.println("Great! Blockchain is Valid.");
+        return true;
+    }
+}
+
+public class HugoByte
+{
+    public static void main(String[] args)
+    {
+        // Create a blockchain
+        Blockchain b = new Blockchain();
+
+        // Add some transactions to test the chain
+        List<String> transactions1 = new LinkedList<>();
+        transactions1.add("Alice sent Rs 100 as her savings to Bob.");
+        transactions1.add("Bob invested Alice's Rs 100 in Mutual Funds.");
+        b.addBlock(transactions1);
+
+        List<String> transactions2 = new LinkedList<>();
+        transactions2.add("Bob got Rs 150 back as Returns from Mutual Funds.");
+        transactions2.add("Bob returned Rs 100 back to Alice retaining the profit he got.");
+        b.addBlock(transactions2);
+
+        // Validate the blockchain
+        b.validate();
+    }
+}

M_Layashree_Assignment/README.md

@@ -0,0 +1,17 @@
+Procedure to run the code:
+
+Ensure that JDK is installed on your local computer.
+If JDK is not installed, then Download and Install JDK from the following link:
+https://www.oracle.com/in/java/technologies/downloads/
+
+Once JDK is installed, Open Command Prompt and enter "java-version". This will display the installed Version number.
+
+To run the code, navigate to the folder containing the code in the command prompt using "cd <space> <Folder_Name>" command.
+
+Once you are in the folder containing the code file, you need to compile and run the code.
+
+To compile the code, enter "javac HugoByte.java". This will generate the .class files.
+
+Next, to run the code, enter "java HugoByte".
+
+This will display the output on your screen.