Added support from Elias Naur for loading a bundled signing certificate instead

of using the signers on the jar file. Also tidied up the code that passes
certificates around so that we get rid of that wonderful Object[] as early as
possible.

src/main/java/com/threerings/getdown/data/Application.java

@@ -188,7 +188,7 @@ public class Application
      * @param appargs additional arguments to pass on to launched application; these will be added
      * after the args in the getdown.txt file.
      */
-    public Application (File appdir, String appid, Object[] signers,
+    public Application (File appdir, String appid, List<Certificate> signers,
                         String[] jvmargs, String[] appargs)
     {
         _appdir = appdir;
@@ -1272,7 +1272,7 @@ public class Application
         File target = downloadFile(path);
 
         if (validateSignature) {
-            if (_signers == null) {
+            if (_signers.isEmpty()) {
                 log.info("No signers, not verifying file", "path", path);
 
             } else {
@@ -1289,12 +1289,7 @@ public class Application
 
                 byte[] buffer = new byte[8192];
                 int length, validated = 0;
-                for (Object signer : _signers) {
-                    if (!(signer instanceof Certificate)) {
-                        continue;
-                    }
-
-                    Certificate cert = (Certificate)signer;
+                for (Certificate cert : _signers) {
                     FileInputStream dataInput = null;
                     try {
                         dataInput = new FileInputStream(target);
@@ -1526,7 +1521,7 @@ public class Application
     protected String[] _extraJvmArgs;
     protected String[] _extraAppArgs;
 
-    protected Object[] _signers;
+    protected List<Certificate> _signers;
 
     /** If a warning has been issued about not being able to set modtimes. */
     protected boolean _warnedAboutSetLastModified;

src/main/java/com/threerings/getdown/launcher/Getdown.java

@@ -25,8 +25,6 @@
 
 package com.threerings.getdown.launcher;
 
-import java.util.Locale;
-
 import java.awt.BorderLayout;
 import java.awt.Container;
 import java.awt.EventQueue;
@@ -50,11 +48,14 @@ import java.net.HttpURLConnection;
 import java.net.URL;
 import java.net.URLConnection;
 
+import java.security.cert.Certificate;
+
 import java.util.ArrayList;
 import java.util.HashSet;
-import java.util.Map;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Locale;
+import java.util.Map;
 import java.util.ResourceBundle;
 import java.util.Set;
 
@@ -95,7 +96,8 @@ public abstract class Getdown extends Thread
         this(appDir, appId, null, null, null);
     }
 
-    public Getdown (File appDir, String appId, Object[] signers, String[] jvmargs, String[] appargs)
+    public Getdown (File appDir, String appId, List<Certificate> signers,
+                    String[] jvmargs, String[] appargs)
     {
         super("Getdown");
         try {

src/main/java/com/threerings/getdown/launcher/GetdownApplet.java

@@ -30,9 +30,17 @@ import java.awt.Image;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.PrintStream;
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.util.ArrayList;
+import java.util.List;
+
+import java.security.cert.Certificate;
+import java.security.cert.CertificateException;
+import java.security.cert.CertificateFactory;
+
 import javax.swing.JApplet;
 import javax.swing.JPanel;
 
@@ -58,10 +66,21 @@ public class GetdownApplet extends JApplet
                 _errmsg = e.getMessage();
             }
 
-            // XXX getSigners() returns all certificates used to sign this applet which may allow
-            // a third party to insert a trusted certificate. This should be replaced with
-            // statically included trusted keys.
-            _getdown = new Getdown(_config.appdir, null, GetdownApplet.class.getSigners(),
+            List<Certificate> signers = new ArrayList<Certificate>();
+            Certificate cert = loadCertificate("resource.crt");
+            if (cert != null) {
+                signers.add(cert);
+            } else {
+                // getSigners() returns all certificates used to sign this applet which may allow a
+                // third party to insert a trusted certificate. This should be avoided.
+                log.warning("No resource certificate found, falling back to class signers");
+                for (Object signer : GetdownApplet.class.getSigners()) {
+                    if (signer instanceof Certificate) {
+                        signers.add((Certificate)signer);
+                    }
+                }
+            }
+            _getdown = new Getdown(_config.appdir, null, signers,
                                    _config.jvmargs, _config.appargs) {
                 @Override
                 protected Container createContainer () {
@@ -160,6 +179,26 @@ public class GetdownApplet extends JApplet
         }
     }
 
+    protected static Certificate loadCertificate (String path)
+    {
+        try {
+            URL keyUrl = GetdownApplet.class.getClassLoader().getResource(path);
+            if (keyUrl == null) {
+                return null;
+            }
+            InputStream is = keyUrl.openStream();
+            try {
+                return CertificateFactory.getInstance("X.509").generateCertificate(is);
+            } finally {
+                is.close();
+            }
+        } catch (CertificateException e) {
+            throw new RuntimeException(e);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
     /** The Getdown configuration as pulled from the applet params */
     protected GetdownAppletConfig _config;