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comparison app/src/main/java/ch/ethz/ssh2/crypto/SecureRandomFix.java @ 438:d29cce60f393

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migrate from Eclipse to Android Studio
author Carl Byington <carl@five-ten-sg.com>
date Thu, 03 Dec 2015 11:23:55 -0800
parents src/ch/ethz/ssh2/crypto/SecureRandomFix.java@bb7d8a7babbe
children 947ea334735d
comparison
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437:208b31032318 438:d29cce60f393
1 //
2 // Copyright (C) 2014 by 510 Software Group
3 // licensed under the GPLv3 or later
4
5 package ch.ethz.ssh2.crypto;
6
7 import android.os.Build;
8 import android.os.Process;
9
10 import java.io.ByteArrayOutputStream;
11 import java.io.DataOutputStream;
12 import java.io.IOException;
13 import java.io.UnsupportedEncodingException;
14 import java.security.SecureRandom;
15
16
17 public class SecureRandomFix extends SecureRandom {
18
19 // http://android-developers.blogspot.com/2013/08/some-securerandom-thoughts.html
20
21 private static final int VERSION_CODE_JELLY_BEAN_MR2 = 18;
22 private static final byte[] BUILD_FINGERPRINT_AND_DEVICE_SERIAL =
23 getBuildFingerprintAndDeviceSerial();
24
25 private static byte[] generateReasonableSeed() {
26 try {
27 ByteArrayOutputStream seedBuffer = new ByteArrayOutputStream();
28 DataOutputStream seedBufferOut =
29 new DataOutputStream(seedBuffer);
30 seedBufferOut.writeLong(System.currentTimeMillis());
31 seedBufferOut.writeLong(System.nanoTime());
32 seedBufferOut.writeInt(Process.myPid());
33 seedBufferOut.writeInt(Process.myUid());
34 seedBufferOut.write(BUILD_FINGERPRINT_AND_DEVICE_SERIAL);
35 seedBufferOut.close();
36 return seedBuffer.toByteArray();
37 } catch (IOException e) {
38 throw new SecurityException("Failed to generate seed", e);
39 }
40 }
41
42 /**
43 * Gets the hardware serial number of this device.
44 *
45 * @return serial number or {@code null} if not available.
46 */
47 private static String getDeviceSerialNumber() {
48 // We're using the Reflection API because Build.SERIAL is only available
49 // since API Level 9 (Gingerbread, Android 2.3).
50 try {
51 return (String) Build.class.getField("SERIAL").get(null);
52 } catch (Exception ignored) {
53 return null;
54 }
55 }
56
57 private static byte[] getBuildFingerprintAndDeviceSerial() {
58 StringBuilder result = new StringBuilder();
59 String fingerprint = Build.FINGERPRINT;
60 if (fingerprint != null) {
61 result.append(fingerprint);
62 }
63 String serial = getDeviceSerialNumber();
64 if (serial != null) {
65 result.append(serial);
66 }
67 try {
68 return result.toString().getBytes("UTF-8");
69 } catch (UnsupportedEncodingException e) {
70 throw new RuntimeException("UTF-8 encoding not supported");
71 }
72 }
73
74 public SecureRandomFix() {
75 super();
76 if (Build.VERSION.SDK_INT > VERSION_CODE_JELLY_BEAN_MR2) {
77 // No need to apply the fix
78 return;
79 }
80 setSeed(generateReasonableSeed());
81 }
82 }