| // Copyright 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| package org.chromium.base; |
| |
| import java.io.FileInputStream; |
| import java.io.IOException; |
| import java.security.SecureRandom; |
| |
| /** |
| * This class contains code to initialize a SecureRandom generator securely on Android platforms |
| * <= 4.3. See |
| * {@link http://android-developers.blogspot.com/2013/08/some-securerandom-thoughts.html}. |
| */ |
| public class SecureRandomInitializer { |
| private static final int NUM_RANDOM_BYTES = 16; |
| |
| private static byte[] sSeedBytes = new byte[NUM_RANDOM_BYTES]; |
| |
| /** |
| * Safely initializes the random number generator, by seeding it with data from /dev/urandom. |
| */ |
| public static void initialize(SecureRandom generator) throws IOException { |
| FileInputStream fis = null; |
| try { |
| fis = new FileInputStream("/dev/urandom"); |
| if (fis.read(sSeedBytes) != sSeedBytes.length) { |
| throw new IOException("Failed to get enough random data."); |
| } |
| generator.setSeed(sSeedBytes); |
| } finally { |
| try { |
| if (fis != null) { |
| fis.close(); |
| } |
| } catch (IOException e) { |
| // Ignore exception closing the device. |
| } |
| } |
| } |
| } |