fix(server): random generate default value

hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/auth/StandardAuthManager.java

@@ -107,6 +107,7 @@
                                                 HugeAccess::fromEdge);
 
         this.tokenGenerator = new TokenGenerator(config);
+        LOG.info("Randomly generate a JWT secret key now");
 
         this.ipWhiteList = new HashSet<>();
 

hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/config/AuthOptions.java

@@ -21,6 +21,9 @@
 import static org.apache.hugegraph.config.OptionChecker.rangeDouble;
 import static org.apache.hugegraph.config.OptionChecker.rangeInt;
 
+import java.security.SecureRandom;
+import java.util.Base64;
+
 public class AuthOptions extends OptionHolder {
 
     private AuthOptions() {
@@ -90,7 +93,7 @@
                     "auth.token_secret",
                     "Secret key of HS256 algorithm.",
                     disallowEmpty(),
-                    "FXQXbJtbCLxODc6tGci732pkH1cyf8Qg"
+                    generateRandomBase64Key()
             );
 
     public static final ConfigOption<Double> AUTH_AUDIT_LOG_RATE =
@@ -126,4 +129,12 @@
                     rangeInt(0L, Long.MAX_VALUE),
                     (3600 * 24L)
             );
+
+    private static String generateRandomBase64Key() {
+        SecureRandom random = new SecureRandom();
+        // 32 bytes for HMAC-SHA256
+        byte[] bytes = new byte[32];
+        random.nextBytes(bytes);
+        return Base64.getEncoder().encodeToString(bytes);
+    }
 }