Add strong salted password hashing using PBKDF2

src/main/java/envoy/server/data/User.java

@@ -63,7 +63,7 @@ public class User extends Contact {
 	public static final String searchByName = "User.searchByName";
 
 	@Column(name = "password_hash")
-	private byte[] passwordHash;
+	private String passwordHash;
 
 	@Column(name = "last_seen")
 	private LocalDateTime lastSeen;
@@ -80,15 +80,15 @@ public class User extends Contact {
 
 	/**
 	 * @return the password hash
-	 * @since Envoy Server Standalone v0.1-alpha
+	 * @since Envoy Server Standalone v0.1-beta
 	 */
-	public byte[] getPasswordHash() { return passwordHash; }
+	public String getPasswordHash() { return passwordHash; }
 
 	/**
 	 * @param passwordHash the password hash to set
-	 * @since Envoy Server Standalone v0.1-alpha
+	 * @since Envoy Server Standalone v0.1-beta
 	 */
-	public void setPasswordHash(byte[] passwordHash) { this.passwordHash = passwordHash; }
+	public void setPasswordHash(String passwordHash) { this.passwordHash = passwordHash; }
 
 	/**
 	 * @return the last date the user has been online

src/main/java/envoy/server/processors/LoginCredentialProcessor.java

@@ -5,7 +5,9 @@ import static envoy.data.User.UserStatus.ONLINE;
 import static envoy.event.HandshakeRejection.*;
 
 import java.time.LocalDateTime;
-import java.util.*;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
 import java.util.logging.Logger;
 
 import javax.persistence.NoResultException;
@@ -19,7 +21,8 @@ import envoy.server.data.PersistenceManager;
 import envoy.server.data.User;
 import envoy.server.net.ConnectionManager;
 import envoy.server.net.ObjectWriteProxy;
-import envoy.server.util.VersionUtils;
+import envoy.server.util.PasswordUtil;
+import envoy.server.util.VersionUtil;
 import envoy.util.Bounds;
 import envoy.util.EnvoyLog;
 
@@ -47,7 +50,7 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 		// Cache this write proxy for user-independant notifications
 		UserStatusChangeProcessor.setWriteProxy(writeProxy);
 
-		if (!VersionUtils.verifyCompatibility(credentials.getClientVersion())) {
+		if (!VersionUtil.verifyCompatibility(credentials.getClientVersion())) {
 			logger.info("The client has the wrong version.");
 			writeProxy.write(socketID, new HandshakeRejection(WRONG_VERSION));
 			return;
@@ -66,7 +69,7 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 					return;
 				}
 				// Evaluating the correctness of the password hash
-				if (!Arrays.equals(credentials.getPasswordHash(), user.getPasswordHash())) {
+				if (!PasswordUtil.validate(credentials.getPassword(), user.getPasswordHash())) {
 					logger.info(user + " has entered the wrong password.");
 					writeProxy.write(socketID, new HandshakeRejection(WRONG_PASSWORD_OR_USER));
 					return;
@@ -97,7 +100,7 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 				user.setName(credentials.getIdentifier());
 				user.setLastSeen(LocalDateTime.now());
 				user.setStatus(ONLINE);
-				user.setPasswordHash(credentials.getPasswordHash());
+				user.setPasswordHash(PasswordUtil.hash(credentials.getPassword()));
 				user.setContacts(new HashSet<>());
 				persistenceManager.addContact(user);
 				logger.info("Registered new " + user);

src/main/java/envoy/server/util/PasswordUtil.java

@@ -0,0 +1,98 @@
+package envoy.server.util;
+
+import java.math.BigInteger;
+import java.security.GeneralSecurityException;
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+
+import javax.crypto.SecretKeyFactory;
+import javax.crypto.spec.PBEKeySpec;
+
+/**
+ * Provides a password hashing and comparison mechanism using the
+ * {@code PBKDF2WithHmacSHA1} algorithm.
+ * <p>
+ * Project: <strong>envoy-server-standalone</strong><br>
+ * File: <strong>PasswordUtil.java</strong><br>
+ * Created: <strong>10.07.2020</strong><br>
+ * 
+ * @author Kai S. K. Engelbart
+ * @since Envoy Server Standalone v0.1-beta
+ */
+public class PasswordUtil {
+
+	private static final int	ITERATIONS				= 1000;
+	private static final int	KEY_LENGTH				= 64 * 8;
+	private static final String	SALT_ALGORITHM			= "SHA1PRNG";
+	private static final String	SECRET_KEY_ALGORITHM	= "PBKDF2WithHmacSHA1";
+
+	private PasswordUtil() {}
+
+	/**
+	 * Validates a password against a stored password hash
+	 *
+	 * @param current the password to validate
+	 * @param stored  the hash to validate against
+	 * @return {@code true} if the password is correct
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public static boolean validate(String current, String stored) {
+		try {
+			String[]	parts		= stored.split(":");
+			int			iterations	= Integer.parseInt(parts[0]);
+			byte[]		salt		= fromHex(parts[1]);
+			byte[]		hash		= fromHex(parts[2]);
+
+			var		spec		= new PBEKeySpec(current.toCharArray(), salt, iterations, KEY_LENGTH);
+			var		skf			= SecretKeyFactory.getInstance(SECRET_KEY_ALGORITHM);
+			byte[]	testHash	= skf.generateSecret(spec).getEncoded();
+
+			int diff = hash.length ^ testHash.length;
+			for (int i = 0; i < hash.length && i < testHash.length; ++i)
+				diff |= hash[i] ^ testHash[i];
+
+			return diff == 0;
+		} catch (GeneralSecurityException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+	/**
+	 * Creates a parameterized salted password hash.
+	 * 
+	 * @param password the password to hash
+	 * @return a result string in the form of {@code iterations:salt:hash}
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public static String hash(String password) {
+		try {
+			byte[]	salt	= salt();
+			var		spec	= new PBEKeySpec(password.toCharArray(), salt, ITERATIONS, KEY_LENGTH);
+			var		skf		= SecretKeyFactory.getInstance(SECRET_KEY_ALGORITHM);
+			byte[]	hash	= skf.generateSecret(spec).getEncoded();
+			return ITERATIONS + ":" + toHex(salt) + ":" + toHex(hash);
+		} catch (GeneralSecurityException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+	private static byte[] salt() throws NoSuchAlgorithmException {
+		SecureRandom	sr		= SecureRandom.getInstance(SALT_ALGORITHM);
+		byte[]			salt	= new byte[16];
+		sr.nextBytes(salt);
+		return salt;
+	}
+
+	private static String toHex(byte[] bytes) {
+		String	hex		= new BigInteger(1, bytes).toString(16);
+		int		padding	= bytes.length * 2 - hex.length();
+		return padding > 0 ? String.format("%0" + padding + "d", 0) + hex : hex;
+	}
+
+	private static byte[] fromHex(String hex) {
+		byte[] bytes = new byte[hex.length() / 2];
+		for (int i = 0; i < bytes.length; ++i)
+			bytes[i] = (byte) Integer.parseInt(hex.substring(2 * i, 2 * i + 2), 16);
+		return bytes;
+	}
+}

src/main/java/envoy/server/util/VersionUtil.java

@@ -7,13 +7,13 @@ import java.util.regex.Pattern;
  * and maximal client versions compatible with this server.
  * <p>
  * Project: <strong>envoy-server-standalone</strong><br>
- * File: <strong>VersionUtils.java</strong><br>
+ * File: <strong>VersionUtil.java</strong><br>
  * Created: <strong>23.06.2020</strong><br>
  * 
  * @author Kai S. K. Engelbart
  * @since Envoy Server Standalone v0.1-beta
  */
-public class VersionUtils {
+public class VersionUtil {
 
 	/**
 	 * The minimal client version compatible with this server.
@@ -31,7 +31,7 @@ public class VersionUtils {
 
 	private static final Pattern versionPattern = Pattern.compile("(?<major>\\d).(?<minor>\\d)(?:-(?<suffix>\\w+))?");
 
-	private VersionUtils() {}
+	private VersionUtil() {}
 
 	/**
 	 * Parses an Envoy Client version string and checks whether that version is