1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 package org.chromium.chromoting; 6 7 import java.io.FileInputStream; 8 import java.io.IOException; 9 import java.security.SecureRandom; 10 11 /** 12 * This class contains code to initialize a SecureRandom generator securely on Android platforms 13 * <= 4.3. See 14 * {@link http://android-developers.blogspot.com/2013/08/some-securerandom-thoughts.html}. 15 */ 16 public class SecureRandomInitializer { 17 private static final int NUM_RANDOM_BYTES = 16; 18 19 /** 20 * Safely initializes the random number generator, by seeding it with data from /dev/urandom. 21 */ 22 public static void initialize(SecureRandom generator) throws IOException { 23 FileInputStream fis = null; 24 try { 25 fis = new FileInputStream("/dev/urandom"); 26 byte[] bytes = new byte[NUM_RANDOM_BYTES]; 27 if (bytes.length != fis.read(bytes)) { 28 throw new IOException("Failed to get enough random data."); 29 } 30 generator.setSeed(bytes); 31 } finally { 32 try { 33 if (fis != null) { 34 fis.close(); 35 } 36 } catch (IOException e) { 37 // Ignore exception closing the device. 38 } 39 } 40 } 41 } 42
