signature check in Android PluginManager

常常看到有人在問android PluginManager裡面的signature 是幹嘛用的
http://android.git.kernel.org/?p=platform/frameworks/base.git;a=blob;f=core/java/android/webkit/PluginManager.java;h=cdcb662e057c4d41b7e7af235991d53037d1e19d;hb=HEAD#l75


查了一下commit的log
原來是當初要給flash on android


commit 73477e7336cd1bdd67984a0f6374c79108a8f098
Author: Grace Kloba
Date:   Wed Sep 30 17:45:46 2009 -0700

    Add the signature checking for WebView plugins. The
    first one is for SampleBrowserPlugin. The second
    one is for Flash.

diff --git a/core/java/android/webkit/PluginManager.java b/core/java/android/webkit/PluginManager.java
index 766bd75..edba446 100644
--- a/core/java/android/webkit/PluginManager.java
+++ b/core/java/android/webkit/PluginManager.java
@@ -65,6 +65,15 @@ public class PluginManager {

     private ArrayList mPackageInfoCache;

+    // Only plugin matches one of the signatures in the list can be loaded
+    // inside the WebView process
+    private static final String SIGNATURE_1 = "308204a830820390a003020102020900936eacbe07f201df300d06092a864886f70d0101050500308194310b3009060355040613025553311330110603550408130a43616c69666f726e69613116301
+    private static final String SIGNATURE_2 = "308204c5308203ada003020102020900d7cb412f75f4887e300d06092a864886f70d010105050030819d310b3009060355040613025553311330110603550408130a43616c69666f726e69613111300
+
+    private static final Signature[] SIGNATURES = new Signature[] {
+        new Signature(SIGNATURE_1), new Signature(SIGNATURE_2)
+    };
+
     private PluginManager(Context context) {
         mContext = context;
         mPackageInfoCache = new ArrayList();
@@ -148,9 +157,12 @@ public class PluginManager {
                 }
                 boolean signatureMatch = false;
                 for (Signature signature : signatures) {
-                    // TODO: check signature against Google provided one
-                    signatureMatch = true;
-                    break;
+                    for (int i = 0; i < SIGNATURES.length; i++) {
+                        if (SIGNATURES[i].equals(signature)) {
+                            signatureMatch = true;
+                            break;
+                        }
+                    }
                 }
                 if (!signatureMatch) {
                     continue;