ContriHUB · nxd010 · Oct 25, 2025
diff --git a/src/Main/Main.java b/src/Main/Main.java
@@ -139,14 +139,26 @@ public static void main(String[] args) throws IOException {
                     switch (command.toLowerCase()) {
                         case "upload":
                             // Start a new thread for upload
-                        	FileData fileupload = new FileData(argument);
-                        	System.out.println("The Hash of the File is " + fileupload.getFileHash());
-                            Handshake.registerFile(fileupload , argument);
-                            break;
+                        	String filePath = argument;
+    						FileData fileupload = new FileData(filePath);
+
+    						System.out.print("Set password for this file? (leave empty for no password): ");
+							String password = scanner.nextLine().trim();
+
+    						if (!password.isEmpty()) {
+        						fileupload.setPasswordHash(FileData.hashPassword(password));
+        						System.out.println("Password protection enabled");
+    							}
+
+    						System.out.println("The Hash of the File is " + fileupload.getFileHash());
+    						Handshake.registerFile(fileupload , filePath);
+    						break;
                         case "download":
-                            // Start a new thread for download
-                            FileReciever.downloadFile(argument, central);
-
+							// Start a new thread for download
+    						System.out.print("File password (leave empty if none): ");
+    						String downloadPassword = scanner.nextLine().trim();
+    						FileReciever.downloadFile(argument, central, downloadPassword);
+
                             break;
                         case "broadcastfile":
                         	FileData f = new FileData(argument);

diff --git a/src/discovery/FileData.java b/src/discovery/FileData.java
@@ -15,6 +15,7 @@ public class FileData implements Serializable{
     private long fileSize; // Size in bytes
     private String fileType; // MIME type or file extension
     private String fileHash; // Checksum or hash for integrity verification
+    private String passwordHash; //SHA-256 hash of Password
 
     // Constructors
     public FileData() {
@@ -77,6 +78,14 @@ public void setFileHash(String fileHash) {
         this.fileHash = fileHash;
     }
 
+    public String getPasswordHash() {
+    return passwordHash;
+    }
+
+    public void setPasswordHash(String passwordHash) {
+    this.passwordHash = passwordHash;
+    }
+
     // Helper method to extract the file extension
     private String getFileExtension(String fileName) {
         int lastDotIndex = fileName.lastIndexOf('.');
@@ -107,6 +116,24 @@ private String calculateFileHash(File file) throws IOException {
             throw new RuntimeException("MD5 algorithm not found.", e);
         }
     }
+
+    //Helper method to Hash Password
+    public static String hashPassword(String password) {
+    if (password == null || password.isEmpty()) {
+        return null;
+    }
+    try {
+        MessageDigest md = MessageDigest.getInstance("SHA-256");
+        byte[] hashBytes = md.digest(password.getBytes());
+        StringBuilder sb = new StringBuilder();
+        for (byte b : hashBytes) {
+            sb.append(String.format("%02x", b));
+        }
+        return sb.toString();
+    } catch (NoSuchAlgorithmException e) {
+        throw new RuntimeException("SHA-256 algorithm not found.", e);
+    }
+    }
 
     // toString method for easy debugging
     @Override

diff --git a/src/discovery/Handshake.java b/src/discovery/Handshake.java
@@ -38,28 +38,54 @@ public static void start(int port, Node c) {
                 FileResponse res;
 
                 if (HashtoFD.containsKey(req.FileData.getFileHash())) {
-                    res = new FileResponse(req.RequestingNode, client, true, Handshake.HashtoFD.get(req.FileData.getFileHash()));
+                    FileData storedFile = Handshake.HashtoFD.get(req.FileData.getFileHash());
 
-                    UserExperience.printStatus("File found, sending response...");
-                    ObjectTransfer.sendObject(socket, res);
+                    // Password Verification
+                    boolean passwordValid = true;
+                    if (storedFile.getPasswordHash() != null) {
+                        // File is password protected
+                        String attemptHash = FileData.hashPassword(req.passwordAttempt);
+                        passwordValid = storedFile.getPasswordHash().equals(attemptHash);
+
+                        if (passwordValid) {
+                            UserExperience.printSuccess("Password verified");
+                        } else {
+                            UserExperience.printWarning("Invalid password");
+                        }
+                    }
 
-                    obj = ObjectTransfer.receiveObject(socket);
-                    TransferRequest treq = (TransferRequest)obj;
 
-                    TransferResponse tres = new TransferResponse(treq.RequestingNode, client, treq.Port, true);
-                    ObjectTransfer.sendObject(socket, tres);
-
-                    socket.close();
-
-                    UserExperience.printSeparator();
-                    UserExperience.printStatus("Starting file transfer to " + req.RequestingNode.getPeerIP());
-
-                    ConnectionHandlerSequential.sendFile(
-                        tres.RequestingNode.getPeerIP(), 
-                        tres.Port, 
-                        Handshake.HashtoPath.get(treq.Fd.getFileHash()), 
-                        req.pub
-                    );
+                    if (passwordValid) {
+                        // Password is correct or no password required - proceed with transfer
+                        res = new FileResponse(req.RequestingNode, client, true, storedFile);
+
+                        UserExperience.printStatus("File found, sending response...");
+                        ObjectTransfer.sendObject(socket, res);
+
+                        obj = ObjectTransfer.receiveObject(socket);
+                        TransferRequest treq = (TransferRequest)obj;
+
+                        TransferResponse tres = new TransferResponse(treq.RequestingNode, client, treq.Port, true);
+                        ObjectTransfer.sendObject(socket, tres);
+
+                        socket.close();
+
+                        UserExperience.printSeparator();
+                        UserExperience.printStatus("Starting file transfer to " + req.RequestingNode.getPeerIP());
+
+                        ConnectionHandlerSequential.sendFile(
+                            tres.RequestingNode.getPeerIP(), 
+                            tres.Port, 
+                            Handshake.HashtoPath.get(treq.Fd.getFileHash()), 
+                            req.pub
+                        );
+                    } else {
+                        // PASSWORD INCORRECT
+                        res = new FileResponse(req.RequestingNode, client, false, storedFile);
+                        ObjectTransfer.sendObject(socket, res);
+                        socket.close();
+                        UserExperience.printSeparator();
+                    }
                 }
 
             } catch (IOException | ClassNotFoundException e) {
@@ -79,6 +105,13 @@ public static void registerFile(FileData f, String path) {
         UserExperience.printStatus("Hash: " + f.getFileHash());
         UserExperience.printStatus("Size: " + UserExperience.formatBytes(f.getFileSize()));
 
+        //SHOW PASSWORD PROTECTION STATUS 
+        if (f.getPasswordHash() != null) {
+            UserExperience.printStatus("Security: Password protected");
+        } else {
+            UserExperience.printStatus("Security: Public (no password)");
+        }
+
         try {
             Socket socket = new Socket(central.getPeerIP(), central.getPeerPort());
             ObjectTransfer.sendObject(socket, req);

diff --git a/src/discovery/messages/FileRequest.java b/src/discovery/messages/FileRequest.java
@@ -10,8 +10,11 @@ public class FileRequest implements Serializable{
 	public FileData FileData;
 	public Node RequestingNode;
 	public PublicKey pub;
-	public FileRequest(FileData f , Node n){
-		this.FileData = f;
-		this.RequestingNode = n;
+	public String passwordAttempt; 
+
+	public FileRequest(FileData f , Node n , String password) { 
+    this.FileData = f;
+    this.RequestingNode = n;
+    this.passwordAttempt = password;
 	}
 }
diff --git a/src/p2p/FileReciever.java b/src/p2p/FileReciever.java
@@ -17,7 +17,8 @@
 
 public class FileReciever {
 
-    public static void downloadFile(String fileHash, Node CentralRegistry) {
+    // Added password parameter 
+    public static void downloadFile(String fileHash, Node CentralRegistry, String password) {
 
         UserExperience.printSeparator();
         UserExperience.printStage(TransferStage.CONNECTING);
@@ -48,7 +49,8 @@ public static void downloadFile(String fileHash, Node CentralRegistry) {
                     UserExperience.printStatus("Attempting download from peer " + (i+1) + "/" + res.peers.length);
                     UserExperience.printStatus("Peer: " + potentialPeer.getPeerIP() + ":" + potentialPeer.getPeerPort());
 
-                    if (FileReciever.downloadFromPeer(potentialPeer, file)) {
+                    // Pass password to downloadFromPeer
+                    if (FileReciever.downloadFromPeer(potentialPeer, file, password)) {
                         UserExperience.printSuccess("Download completed successfully!");
                         downloaded = true;
                         break;
@@ -73,9 +75,11 @@ public static void downloadFile(String fileHash, Node CentralRegistry) {
         }
     }
 
-    public static boolean downloadFromPeer(Node peer, FileData f) {
-        Node two = Handshake.getClient();
-        FileRequest req = new FileRequest(f, two);
+    // Added password parameter
+    public static boolean downloadFromPeer(Node peer, FileData f, String password) {
+        Node two = Handshake.getClient();       
+        // Pass password in FileRequest constructor
+        FileRequest req = new FileRequest(f, two, password);
 
         try {
             UserExperience.printStage(TransferStage.NEGOTIATING);
@@ -93,6 +97,14 @@ public static boolean downloadFromPeer(Node peer, FileData f) {
 
             Object obj = ObjectTransfer.receiveObject(socket);
             FileResponse res = (FileResponse)obj;
+
+            // Check if rejected due to wrong password 
+            if (!res.response) {
+                UserExperience.printWarning("Access denied - Invalid password");
+                socket.close();
+                return false;
+            }
+
             String fileName = res.file.getFileName();
 
             UserExperience.printSuccess("Peer accepted request for: " + fileName);

diff --git a/src/testing/FileTesting.java b/src/testing/FileTesting.java
@@ -85,6 +85,8 @@ public static void senderThread(String []files , Thread recieverThread) {
             t.start(); //this thread line will be started for each of the peer
             for(String filePath : files) {
             	FileData f = new FileData(filePath);
+            	// Explicitly set no password 
+            	f.setPasswordHash(null); // No password for tests
                 Handshake.registerFile(f , filePath);
             }
             recieverThread.start();
@@ -97,16 +99,30 @@ public static void senderThread(String []files , Thread recieverThread) {
 
 	public static void recieverThread(String []hashes) {
 		Node client = new Node();
-    	client.setPeerIP(SenderIP);
-    	client.setPeerPort(SenderPort);
+    	client.setPeerIP(RecieverIP); // FIXED: Was SenderIP, should be RecieverIP ***
+    	client.setPeerPort(RecieverPort); // FIXED: Was SenderPort, should be RecieverPort ***
 
     	Node central = new Node();
     	central.setPeerIP(CentralIP);
     	central.setPeerPort(CentralPort);
 
+    	// Initialize Handshake for receiver
+    	Handshake.setClient(client);
+    	Handshake.setCentralRegistry(central);
+    	Thread t = new Thread(() -> Handshake.start(client.getPeerPort() , client));
+        t.start();
+
+        // Small delay to ensure receiver is ready
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+
     	for(String hash : hashes) {
-    		FileReciever.downloadFile(hash, central);
+    		// Pass null password for test downloads
+    		FileReciever.downloadFile(hash, central, null);
     	}
 
 	}
-}
+}