1 files changed, 126 insertions, 0 deletions
diff --git a/input/autofill/AutofillFramework/Application/src/main/java/com/example/android/autofillframework/multidatasetservice/datasource/SharedPrefsPackageVerificationRepository.java b/input/autofill/AutofillFramework/Application/src/main/java/com/example/android/autofillframework/multidatasetservice/datasource/SharedPrefsPackageVerificationRepository.java
new file mode 100644
index 00000000..b7bb5828
--- /dev/null
+++ b/input/autofill/AutofillFramework/Application/src/main/java/com/example/android/autofillframework/multidatasetservice/datasource/SharedPrefsPackageVerificationRepository.java
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.autofillframework.multidatasetservice.datasource;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.Signature;
+import android.util.Log;
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+import java.security.MessageDigest;
+import java.security.cert.CertificateFactory;
+import java.security.cert.X509Certificate;
+
+import static com.example.android.autofillframework.CommonUtil.TAG;
+
+public class SharedPrefsPackageVerificationRepository implements PackageVerificationDataSource {
+
+    private static final String SHARED_PREF_KEY = "com.example.android.autofillframework"
+            + ".multidatasetservice.datasource.PackageVerificationDataSource";
+    private static PackageVerificationDataSource sInstance;
+
+    private SharedPrefsPackageVerificationRepository() {
+    }
+
+    public static PackageVerificationDataSource getInstance() {
+        if (sInstance == null) {
+            sInstance = new SharedPrefsPackageVerificationRepository();
+        }
+        return sInstance;
+    }
+
+    @Override
+    public void clear(Context context) {
+        context.getApplicationContext().getSharedPreferences(SHARED_PREF_KEY, Context.MODE_PRIVATE)
+                .edit()
+                .clear()
+                .apply();
+    }
+
+    @Override
+    public boolean putPackageSignatures(Context context, String packageName) {
+        String hash;
+        try {
+            hash = getCertificateHash(context, packageName);
+            Log.d(TAG, "Hash for " + packageName + ": " + hash);
+        } catch (Exception e) {
+            Log.w(TAG, "Error getting hash for " + packageName + ": " + e);
+            return false;
+        }
+
+        if (!containsSignatureForPackage(context, packageName)) {
+            // Storage does not yet contain signature for this package name.
+            context.getApplicationContext()
+                    .getSharedPreferences(SHARED_PREF_KEY, Context.MODE_PRIVATE)
+                    .edit()
+                    .putString(packageName, hash)
+                    .apply();
+            return true;
+        }
+        return containsMatchingSignatureForPackage(context, packageName, hash);
+    }
+
+    private boolean containsSignatureForPackage(Context context, String packageName) {
+        SharedPreferences prefs = context.getApplicationContext().getSharedPreferences(
+                SHARED_PREF_KEY, Context.MODE_PRIVATE);
+        return prefs.contains(packageName);
+    }
+
+    private boolean containsMatchingSignatureForPackage(Context context, String packageName,
+            String hash) {
+        SharedPreferences prefs = context.getApplicationContext().getSharedPreferences(
+                SHARED_PREF_KEY, Context.MODE_PRIVATE);
+        return hash.equals(prefs.getString(packageName, null));
+    }
+
+    private String getCertificateHash(Context context, String packageName)
+            throws Exception {
+        PackageManager pm = context.getPackageManager();
+        PackageInfo packageInfo = pm.getPackageInfo(packageName, PackageManager.GET_SIGNATURES);
+        Signature[] signatures = packageInfo.signatures;
+        byte[] cert = signatures[0].toByteArray();
+        try (InputStream input = new ByteArrayInputStream(cert)) {
+            CertificateFactory factory = CertificateFactory.getInstance("X509");
+            X509Certificate x509 = (X509Certificate) factory.generateCertificate(input);
+            MessageDigest md = MessageDigest.getInstance("SHA256");
+            byte[] publicKey = md.digest(x509.getEncoded());
+            return toHexFormat(publicKey);
+        }
+    }
+
+    private String toHexFormat(byte[] bytes) {
+        StringBuilder builder = new StringBuilder(bytes.length * 2);
+        for (int i = 0; i < bytes.length; i++) {
+            String hex = Integer.toHexString(bytes[i]);
+            int length = hex.length();
+            if (length == 1) {
+                hex = "0" + hex;
+            }
+            if (length > 2) {
+                hex = hex.substring(length - 2, length);
+            }
+            builder.append(hex.toUpperCase());
+            if (i < (bytes.length - 1)) {
+                builder.append(':');
+            }
+        }
+        return builder.toString();
+    }
+}