Add optional additional entropy to finish

If provided the extra entropy will be added to the device before calling
finish. If entropy is provided and the device does not support supplying
additional entropy then finish will fail with KM_ERROR_UNIMPLEMENTED.

(cherry-picked from commit 9ce30624a4)

Change-Id: If26be118bf382604f6f8e96e833b76e6f9e94d58

core/java/android/security/IKeystoreService.aidl

@@ -67,7 +67,8 @@ interface IKeystoreService {
     OperationResult begin(IBinder appToken, String alias, int purpose, boolean pruneable,
         in KeymasterArguments params, in byte[] entropy);
     OperationResult update(IBinder token, in KeymasterArguments params, in byte[] input);
-    OperationResult finish(IBinder token, in KeymasterArguments params, in byte[] signature);
+    OperationResult finish(IBinder token, in KeymasterArguments params, in byte[] signature,
+        in byte[] entropy);
     int abort(IBinder handle);
     boolean isOperationAuthorized(IBinder token);
     int addAuthToken(in byte[] authToken);

keystore/java/android/security/KeyStore.java

@@ -514,15 +514,20 @@ public class KeyStore {
         }
     }
 
-    public OperationResult finish(IBinder token, KeymasterArguments arguments, byte[] signature) {
+    public OperationResult finish(IBinder token, KeymasterArguments arguments, byte[] signature,
+            byte[] entropy) {
         try {
-            return mBinder.finish(token, arguments, signature);
+            return mBinder.finish(token, arguments, signature, entropy);
         } catch (RemoteException e) {
             Log.w(TAG, "Cannot connect to keystore", e);
             return null;
         }
     }
 
+    public OperationResult finish(IBinder token, KeymasterArguments arguments, byte[] signature) {
+        return finish(token, arguments, signature, null);
+    }
+
     public int abort(IBinder token) {
         try {
             return mBinder.abort(token);