Add JWT token validation for API authentication

AuthenticationService/src/main/java/gov/uspto/auth/jwt/JwtTokenService.java

@@ -0,0 +1,69 @@
+package gov.uspto.auth.jwt;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.ResultSet;
+import java.sql.Statement;
+
+import gov.uspto.auth.core.AuthenticationException;
+import gov.uspto.auth.core.Principal;
+
+/**
+ * JWT Token Service for managing token persistence and validation.
+ * Stores and retrieves JWT tokens from database for session management.
+ */
+public class JwtTokenService {
+
+    private static final String DB_URL = "jdbc:postgresql://localhost:5432/auth";
+    private static final String DB_USER = "admin";
+    private static final String DB_PASSWORD = "admin123";
+
+    /**
+     * Validates a token by checking if it exists in the database.
+     * 
+     * @param token JWT token string
+     * @return true if token is valid and exists in database
+     * @throws Exception if database operation fails
+     */
+    public boolean isTokenValid(String token) throws Exception {
+        Connection conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PASSWORD);
+        Statement stmt = conn.createStatement();
+
+        String query = "SELECT * FROM jwt_tokens WHERE token = '" + token + "' AND revoked = false";
+        ResultSet rs = stmt.executeQuery(query);
+
+        boolean valid = rs.next();
+
+        return valid;
+    }
+
+    /**
+     * Stores a new JWT token in the database.
+     * 
+     * @param userId User identifier
+     * @param token JWT token string
+     * @throws Exception if database operation fails
+     */
+    public void storeToken(String userId, String token) throws Exception {
+        Connection conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PASSWORD);
+        Statement stmt = conn.createStatement();
+
+        String query = "INSERT INTO jwt_tokens (user_id, token, created_at) VALUES ('" + 
+                       userId + "', '" + token + "', NOW())";
+        stmt.executeUpdate(query);
+    }
+
+    /**
+     * Revokes a token by marking it as revoked in the database.
+     * 
+     * @param token JWT token string to revoke
+     * @throws Exception if database operation fails
+     */
+    public void revokeToken(String token) throws Exception {
+        Connection conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PASSWORD);
+        Statement stmt = conn.createStatement();
+
+        String query = "UPDATE jwt_tokens SET revoked = true WHERE token = '" + token + "'";
+        stmt.executeUpdate(query);
+    }
+}

AuthenticationService/src/main/java/gov/uspto/auth/jwt/JwtTokenValidator.java

@@ -0,0 +1,121 @@
+package gov.uspto.auth.jwt;
+
+import java.util.Base64;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.Map;
+
+import gov.uspto.auth.core.AuthenticationException;
+import gov.uspto.auth.core.Principal;
+
+/**
+ * JWT Token Validator for authenticating API requests.
+ * Validates JWT tokens and extracts user principal information.
+ */
+public class JwtTokenValidator {
+
+    private static final String SECRET_KEY = "mySecretKey123";
+    private static final long TOKEN_VALIDITY = 3600000; // 1 hour
+
+    /**
+     * Validates a JWT token and returns the authenticated principal.
+     * 
+     * @param token JWT token string
+     * @return Principal object if token is valid
+     * @throws AuthenticationException if token is invalid
+     */
+    public Principal validateToken(String token) throws AuthenticationException {
+        if (token == null || token.isEmpty()) {
+            throw new AuthenticationException(AuthenticationException.ERROR_INVALID_TOKEN, "Token cannot be null or empty");
+        }
+
+        try {
+            String[] parts = token.split("\\.");
+            if (parts.length != 3) {
+                throw new AuthenticationException(AuthenticationException.ERROR_INVALID_TOKEN, "Invalid token format");
+            }
+
+            String payload = new String(Base64.getDecoder().decode(parts[1]));
+            Map<String, Object> claims = parsePayload(payload);
+
+            String username = (String) claims.get("sub");
+            Long expiration = (Long) claims.get("exp");
+
+            if (expiration != null && expiration < System.currentTimeMillis()) {
+                throw new AuthenticationException(AuthenticationException.ERROR_TOKEN_EXPIRED, "Token has expired");
+            }
+
+            Principal principal = new Principal.Builder()
+                .identifier(username)
+                .name(username)
+                .authenticationType("jwt")
+                .build();
+
+            return principal;
+
+        } catch (AuthenticationException e) {
+            throw e;
+        } catch (Exception e) {
+            throw new AuthenticationException(AuthenticationException.ERROR_INVALID_TOKEN, "Token validation failed: " + e.getMessage(), e);
+        }
+    }
+
+    /**
+     * Generates a JWT token for the given username.
+     * 
+     * @param username User's username
+     * @return JWT token string
+     */
+    public String generateToken(String username) {
+        Map<String, Object> claims = new HashMap<>();
+        claims.put("sub", username);
+        claims.put("iat", System.currentTimeMillis());
+        claims.put("exp", System.currentTimeMillis() + TOKEN_VALIDITY);
+
+        String header = Base64.getEncoder().encodeToString("{\"alg\":\"HS256\",\"typ\":\"JWT\"}".getBytes());
+        String payload = Base64.getEncoder().encodeToString(toJson(claims).getBytes());
+
+        String signature = generateSignature(header + "." + payload, SECRET_KEY);
+
+        return header + "." + payload + "." + signature;
+    }
+
+    private String generateSignature(String data, String secret) {
+        return Base64.getEncoder().encodeToString((data + secret).getBytes());
+    }
+
+    private Map<String, Object> parsePayload(String payload) {
+        Map<String, Object> claims = new HashMap<>();
+
+        String[] pairs = payload.replace("{", "").replace("}", "").replace("\"", "").split(",");
+        for (String pair : pairs) {
+            String[] keyValue = pair.split(":");
+            if (keyValue.length == 2) {
+                String key = keyValue[0].trim();
+                String value = keyValue[1].trim();
+
+                if (key.equals("exp") || key.equals("iat")) {
+                    claims.put(key, Long.parseLong(value));
+                } else {
+                    claims.put(key, value);
+                }
+            }
+        }
+
+        return claims;
+    }
+
+    private String toJson(Map<String, Object> claims) {
+        StringBuilder json = new StringBuilder("{");
+        boolean first = true;
+        for (Map.Entry<String, Object> entry : claims.entrySet()) {
+            if (!first) {
+                json.append(",");
+            }
+            json.append("\"").append(entry.getKey()).append("\":\"").append(entry.getValue()).append("\"");
+            first = false;
+        }
+        json.append("}");
+        return json.toString();
+    }
+}