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-rw-r--r--src/eu/siacs/conversations/utils/PRNGFixes.java539
1 files changed, 270 insertions, 269 deletions
diff --git a/src/eu/siacs/conversations/utils/PRNGFixes.java b/src/eu/siacs/conversations/utils/PRNGFixes.java
index cf28ff30..8fe67234 100644
--- a/src/eu/siacs/conversations/utils/PRNGFixes.java
+++ b/src/eu/siacs/conversations/utils/PRNGFixes.java
@@ -21,306 +21,307 @@ import java.security.Security;
/**
* Fixes for the output of the default PRNG having low entropy.
- *
+ *
* The fixes need to be applied via {@link #apply()} before any use of Java
* Cryptography Architecture primitives. A good place to invoke them is in the
* application's {@code onCreate}.
*/
public final class PRNGFixes {
- private static final int VERSION_CODE_JELLY_BEAN = 16;
- private static final int VERSION_CODE_JELLY_BEAN_MR2 = 18;
- private static final byte[] BUILD_FINGERPRINT_AND_DEVICE_SERIAL =
- getBuildFingerprintAndDeviceSerial();
+ private static final int VERSION_CODE_JELLY_BEAN = 16;
+ private static final int VERSION_CODE_JELLY_BEAN_MR2 = 18;
+ private static final byte[] BUILD_FINGERPRINT_AND_DEVICE_SERIAL = getBuildFingerprintAndDeviceSerial();
- /** Hidden constructor to prevent instantiation. */
- private PRNGFixes() {}
+ /** Hidden constructor to prevent instantiation. */
+ private PRNGFixes() {
+ }
- /**
- * Applies all fixes.
- *
- * @throws SecurityException if a fix is needed but could not be applied.
- */
- public static void apply() {
- applyOpenSSLFix();
- installLinuxPRNGSecureRandom();
- }
+ /**
+ * Applies all fixes.
+ *
+ * @throws SecurityException
+ * if a fix is needed but could not be applied.
+ */
+ public static void apply() {
+ applyOpenSSLFix();
+ installLinuxPRNGSecureRandom();
+ }
- /**
- * Applies the fix for OpenSSL PRNG having low entropy. Does nothing if the
- * fix is not needed.
- *
- * @throws SecurityException if the fix is needed but could not be applied.
- */
- private static void applyOpenSSLFix() throws SecurityException {
- if ((Build.VERSION.SDK_INT < VERSION_CODE_JELLY_BEAN)
- || (Build.VERSION.SDK_INT > VERSION_CODE_JELLY_BEAN_MR2)) {
- // No need to apply the fix
- return;
- }
+ /**
+ * Applies the fix for OpenSSL PRNG having low entropy. Does nothing if the
+ * fix is not needed.
+ *
+ * @throws SecurityException
+ * if the fix is needed but could not be applied.
+ */
+ private static void applyOpenSSLFix() throws SecurityException {
+ if ((Build.VERSION.SDK_INT < VERSION_CODE_JELLY_BEAN)
+ || (Build.VERSION.SDK_INT > VERSION_CODE_JELLY_BEAN_MR2)) {
+ // No need to apply the fix
+ return;
+ }
- try {
- // Mix in the device- and invocation-specific seed.
- Class.forName("org.apache.harmony.xnet.provider.jsse.NativeCrypto")
- .getMethod("RAND_seed", byte[].class)
- .invoke(null, generateSeed());
+ try {
+ // Mix in the device- and invocation-specific seed.
+ Class.forName("org.apache.harmony.xnet.provider.jsse.NativeCrypto")
+ .getMethod("RAND_seed", byte[].class)
+ .invoke(null, generateSeed());
- // Mix output of Linux PRNG into OpenSSL's PRNG
- int bytesRead = (Integer) Class.forName(
- "org.apache.harmony.xnet.provider.jsse.NativeCrypto")
- .getMethod("RAND_load_file", String.class, long.class)
- .invoke(null, "/dev/urandom", 1024);
- if (bytesRead != 1024) {
- throw new IOException(
- "Unexpected number of bytes read from Linux PRNG: "
- + bytesRead);
- }
- } catch (Exception e) {
- throw new SecurityException("Failed to seed OpenSSL PRNG", e);
- }
- }
+ // Mix output of Linux PRNG into OpenSSL's PRNG
+ int bytesRead = (Integer) Class
+ .forName(
+ "org.apache.harmony.xnet.provider.jsse.NativeCrypto")
+ .getMethod("RAND_load_file", String.class, long.class)
+ .invoke(null, "/dev/urandom", 1024);
+ if (bytesRead != 1024) {
+ throw new IOException(
+ "Unexpected number of bytes read from Linux PRNG: "
+ + bytesRead);
+ }
+ } catch (Exception e) {
+ throw new SecurityException("Failed to seed OpenSSL PRNG", e);
+ }
+ }
- /**
- * Installs a Linux PRNG-backed {@code SecureRandom} implementation as the
- * default. Does nothing if the implementation is already the default or if
- * there is not need to install the implementation.
- *
- * @throws SecurityException if the fix is needed but could not be applied.
- */
- private static void installLinuxPRNGSecureRandom()
- throws SecurityException {
- if (Build.VERSION.SDK_INT > VERSION_CODE_JELLY_BEAN_MR2) {
- // No need to apply the fix
- return;
- }
+ /**
+ * Installs a Linux PRNG-backed {@code SecureRandom} implementation as the
+ * default. Does nothing if the implementation is already the default or if
+ * there is not need to install the implementation.
+ *
+ * @throws SecurityException
+ * if the fix is needed but could not be applied.
+ */
+ private static void installLinuxPRNGSecureRandom() throws SecurityException {
+ if (Build.VERSION.SDK_INT > VERSION_CODE_JELLY_BEAN_MR2) {
+ // No need to apply the fix
+ return;
+ }
- // Install a Linux PRNG-based SecureRandom implementation as the
- // default, if not yet installed.
- Provider[] secureRandomProviders =
- Security.getProviders("SecureRandom.SHA1PRNG");
- if ((secureRandomProviders == null)
- || (secureRandomProviders.length < 1)
- || (!LinuxPRNGSecureRandomProvider.class.equals(
- secureRandomProviders[0].getClass()))) {
- Security.insertProviderAt(new LinuxPRNGSecureRandomProvider(), 1);
- }
+ // Install a Linux PRNG-based SecureRandom implementation as the
+ // default, if not yet installed.
+ Provider[] secureRandomProviders = Security
+ .getProviders("SecureRandom.SHA1PRNG");
+ if ((secureRandomProviders == null)
+ || (secureRandomProviders.length < 1)
+ || (!LinuxPRNGSecureRandomProvider.class
+ .equals(secureRandomProviders[0].getClass()))) {
+ Security.insertProviderAt(new LinuxPRNGSecureRandomProvider(), 1);
+ }
- // Assert that new SecureRandom() and
- // SecureRandom.getInstance("SHA1PRNG") return a SecureRandom backed
- // by the Linux PRNG-based SecureRandom implementation.
- SecureRandom rng1 = new SecureRandom();
- if (!LinuxPRNGSecureRandomProvider.class.equals(
- rng1.getProvider().getClass())) {
- throw new SecurityException(
- "new SecureRandom() backed by wrong Provider: "
- + rng1.getProvider().getClass());
- }
+ // Assert that new SecureRandom() and
+ // SecureRandom.getInstance("SHA1PRNG") return a SecureRandom backed
+ // by the Linux PRNG-based SecureRandom implementation.
+ SecureRandom rng1 = new SecureRandom();
+ if (!LinuxPRNGSecureRandomProvider.class.equals(rng1.getProvider()
+ .getClass())) {
+ throw new SecurityException(
+ "new SecureRandom() backed by wrong Provider: "
+ + rng1.getProvider().getClass());
+ }
- SecureRandom rng2;
- try {
- rng2 = SecureRandom.getInstance("SHA1PRNG");
- } catch (NoSuchAlgorithmException e) {
- throw new SecurityException("SHA1PRNG not available", e);
- }
- if (!LinuxPRNGSecureRandomProvider.class.equals(
- rng2.getProvider().getClass())) {
- throw new SecurityException(
- "SecureRandom.getInstance(\"SHA1PRNG\") backed by wrong"
- + " Provider: " + rng2.getProvider().getClass());
- }
- }
+ SecureRandom rng2;
+ try {
+ rng2 = SecureRandom.getInstance("SHA1PRNG");
+ } catch (NoSuchAlgorithmException e) {
+ throw new SecurityException("SHA1PRNG not available", e);
+ }
+ if (!LinuxPRNGSecureRandomProvider.class.equals(rng2.getProvider()
+ .getClass())) {
+ throw new SecurityException(
+ "SecureRandom.getInstance(\"SHA1PRNG\") backed by wrong"
+ + " Provider: " + rng2.getProvider().getClass());
+ }
+ }
- /**
- * {@code Provider} of {@code SecureRandom} engines which pass through
- * all requests to the Linux PRNG.
- */
- private static class LinuxPRNGSecureRandomProvider extends Provider {
+ /**
+ * {@code Provider} of {@code SecureRandom} engines which pass through all
+ * requests to the Linux PRNG.
+ */
+ private static class LinuxPRNGSecureRandomProvider extends Provider {
- public LinuxPRNGSecureRandomProvider() {
- super("LinuxPRNG",
- 1.0,
- "A Linux-specific random number provider that uses"
- + " /dev/urandom");
- // Although /dev/urandom is not a SHA-1 PRNG, some apps
- // explicitly request a SHA1PRNG SecureRandom and we thus need to
- // prevent them from getting the default implementation whose output
- // may have low entropy.
- put("SecureRandom.SHA1PRNG", LinuxPRNGSecureRandom.class.getName());
- put("SecureRandom.SHA1PRNG ImplementedIn", "Software");
- }
- }
+ public LinuxPRNGSecureRandomProvider() {
+ super("LinuxPRNG", 1.0,
+ "A Linux-specific random number provider that uses"
+ + " /dev/urandom");
+ // Although /dev/urandom is not a SHA-1 PRNG, some apps
+ // explicitly request a SHA1PRNG SecureRandom and we thus need to
+ // prevent them from getting the default implementation whose output
+ // may have low entropy.
+ put("SecureRandom.SHA1PRNG", LinuxPRNGSecureRandom.class.getName());
+ put("SecureRandom.SHA1PRNG ImplementedIn", "Software");
+ }
+ }
- /**
- * {@link SecureRandomSpi} which passes all requests to the Linux PRNG
- * ({@code /dev/urandom}).
- */
- public static class LinuxPRNGSecureRandom extends SecureRandomSpi {
+ /**
+ * {@link SecureRandomSpi} which passes all requests to the Linux PRNG (
+ * {@code /dev/urandom}).
+ */
+ public static class LinuxPRNGSecureRandom extends SecureRandomSpi {
- /*
- * IMPLEMENTATION NOTE: Requests to generate bytes and to mix in a seed
- * are passed through to the Linux PRNG (/dev/urandom). Instances of
- * this class seed themselves by mixing in the current time, PID, UID,
- * build fingerprint, and hardware serial number (where available) into
- * Linux PRNG.
- *
- * Concurrency: Read requests to the underlying Linux PRNG are
- * serialized (on sLock) to ensure that multiple threads do not get
- * duplicated PRNG output.
- */
+ /*
+ * IMPLEMENTATION NOTE: Requests to generate bytes and to mix in a seed
+ * are passed through to the Linux PRNG (/dev/urandom). Instances of
+ * this class seed themselves by mixing in the current time, PID, UID,
+ * build fingerprint, and hardware serial number (where available) into
+ * Linux PRNG.
+ *
+ * Concurrency: Read requests to the underlying Linux PRNG are
+ * serialized (on sLock) to ensure that multiple threads do not get
+ * duplicated PRNG output.
+ */
- private static final File URANDOM_FILE = new File("/dev/urandom");
+ private static final File URANDOM_FILE = new File("/dev/urandom");
- private static final Object sLock = new Object();
+ private static final Object sLock = new Object();
- /**
- * Input stream for reading from Linux PRNG or {@code null} if not yet
- * opened.
- *
- * @GuardedBy("sLock")
- */
- private static DataInputStream sUrandomIn;
+ /**
+ * Input stream for reading from Linux PRNG or {@code null} if not yet
+ * opened.
+ *
+ * @GuardedBy("sLock")
+ */
+ private static DataInputStream sUrandomIn;
- /**
- * Output stream for writing to Linux PRNG or {@code null} if not yet
- * opened.
- *
- * @GuardedBy("sLock")
- */
- private static OutputStream sUrandomOut;
+ /**
+ * Output stream for writing to Linux PRNG or {@code null} if not yet
+ * opened.
+ *
+ * @GuardedBy("sLock")
+ */
+ private static OutputStream sUrandomOut;
- /**
- * Whether this engine instance has been seeded. This is needed because
- * each instance needs to seed itself if the client does not explicitly
- * seed it.
- */
- private boolean mSeeded;
+ /**
+ * Whether this engine instance has been seeded. This is needed because
+ * each instance needs to seed itself if the client does not explicitly
+ * seed it.
+ */
+ private boolean mSeeded;
- @Override
- protected void engineSetSeed(byte[] bytes) {
- try {
- OutputStream out;
- synchronized (sLock) {
- out = getUrandomOutputStream();
- }
- out.write(bytes);
- out.flush();
- } catch (IOException e) {
- // On a small fraction of devices /dev/urandom is not writable.
- // Log and ignore.
- Log.w(PRNGFixes.class.getSimpleName(),
- "Failed to mix seed into " + URANDOM_FILE);
- } finally {
- mSeeded = true;
- }
- }
+ @Override
+ protected void engineSetSeed(byte[] bytes) {
+ try {
+ OutputStream out;
+ synchronized (sLock) {
+ out = getUrandomOutputStream();
+ }
+ out.write(bytes);
+ out.flush();
+ } catch (IOException e) {
+ // On a small fraction of devices /dev/urandom is not writable.
+ // Log and ignore.
+ Log.w(PRNGFixes.class.getSimpleName(),
+ "Failed to mix seed into " + URANDOM_FILE);
+ } finally {
+ mSeeded = true;
+ }
+ }
- @Override
- protected void engineNextBytes(byte[] bytes) {
- if (!mSeeded) {
- // Mix in the device- and invocation-specific seed.
- engineSetSeed(generateSeed());
- }
+ @Override
+ protected void engineNextBytes(byte[] bytes) {
+ if (!mSeeded) {
+ // Mix in the device- and invocation-specific seed.
+ engineSetSeed(generateSeed());
+ }
- try {
- DataInputStream in;
- synchronized (sLock) {
- in = getUrandomInputStream();
- }
- synchronized (in) {
- in.readFully(bytes);
- }
- } catch (IOException e) {
- throw new SecurityException(
- "Failed to read from " + URANDOM_FILE, e);
- }
- }
+ try {
+ DataInputStream in;
+ synchronized (sLock) {
+ in = getUrandomInputStream();
+ }
+ synchronized (in) {
+ in.readFully(bytes);
+ }
+ } catch (IOException e) {
+ throw new SecurityException("Failed to read from "
+ + URANDOM_FILE, e);
+ }
+ }
- @Override
- protected byte[] engineGenerateSeed(int size) {
- byte[] seed = new byte[size];
- engineNextBytes(seed);
- return seed;
- }
+ @Override
+ protected byte[] engineGenerateSeed(int size) {
+ byte[] seed = new byte[size];
+ engineNextBytes(seed);
+ return seed;
+ }
- private DataInputStream getUrandomInputStream() {
- synchronized (sLock) {
- if (sUrandomIn == null) {
- // NOTE: Consider inserting a BufferedInputStream between
- // DataInputStream and FileInputStream if you need higher
- // PRNG output performance and can live with future PRNG
- // output being pulled into this process prematurely.
- try {
- sUrandomIn = new DataInputStream(
- new FileInputStream(URANDOM_FILE));
- } catch (IOException e) {
- throw new SecurityException("Failed to open "
- + URANDOM_FILE + " for reading", e);
- }
- }
- return sUrandomIn;
- }
- }
+ private DataInputStream getUrandomInputStream() {
+ synchronized (sLock) {
+ if (sUrandomIn == null) {
+ // NOTE: Consider inserting a BufferedInputStream between
+ // DataInputStream and FileInputStream if you need higher
+ // PRNG output performance and can live with future PRNG
+ // output being pulled into this process prematurely.
+ try {
+ sUrandomIn = new DataInputStream(new FileInputStream(
+ URANDOM_FILE));
+ } catch (IOException e) {
+ throw new SecurityException("Failed to open "
+ + URANDOM_FILE + " for reading", e);
+ }
+ }
+ return sUrandomIn;
+ }
+ }
- private OutputStream getUrandomOutputStream() throws IOException {
- synchronized (sLock) {
- if (sUrandomOut == null) {
- sUrandomOut = new FileOutputStream(URANDOM_FILE);
- }
- return sUrandomOut;
- }
- }
- }
+ private OutputStream getUrandomOutputStream() throws IOException {
+ synchronized (sLock) {
+ if (sUrandomOut == null) {
+ sUrandomOut = new FileOutputStream(URANDOM_FILE);
+ }
+ return sUrandomOut;
+ }
+ }
+ }
- /**
- * Generates a device- and invocation-specific seed to be mixed into the
- * Linux PRNG.
- */
- private static byte[] generateSeed() {
- try {
- ByteArrayOutputStream seedBuffer = new ByteArrayOutputStream();
- DataOutputStream seedBufferOut =
- new DataOutputStream(seedBuffer);
- seedBufferOut.writeLong(System.currentTimeMillis());
- seedBufferOut.writeLong(System.nanoTime());
- seedBufferOut.writeInt(Process.myPid());
- seedBufferOut.writeInt(Process.myUid());
- seedBufferOut.write(BUILD_FINGERPRINT_AND_DEVICE_SERIAL);
- seedBufferOut.close();
- return seedBuffer.toByteArray();
- } catch (IOException e) {
- throw new SecurityException("Failed to generate seed", e);
- }
- }
+ /**
+ * Generates a device- and invocation-specific seed to be mixed into the
+ * Linux PRNG.
+ */
+ private static byte[] generateSeed() {
+ try {
+ ByteArrayOutputStream seedBuffer = new ByteArrayOutputStream();
+ DataOutputStream seedBufferOut = new DataOutputStream(seedBuffer);
+ seedBufferOut.writeLong(System.currentTimeMillis());
+ seedBufferOut.writeLong(System.nanoTime());
+ seedBufferOut.writeInt(Process.myPid());
+ seedBufferOut.writeInt(Process.myUid());
+ seedBufferOut.write(BUILD_FINGERPRINT_AND_DEVICE_SERIAL);
+ seedBufferOut.close();
+ return seedBuffer.toByteArray();
+ } catch (IOException e) {
+ throw new SecurityException("Failed to generate seed", e);
+ }
+ }
- /**
- * Gets the hardware serial number of this device.
- *
- * @return serial number or {@code null} if not available.
- */
- private static String getDeviceSerialNumber() {
- // We're using the Reflection API because Build.SERIAL is only available
- // since API Level 9 (Gingerbread, Android 2.3).
- try {
- return (String) Build.class.getField("SERIAL").get(null);
- } catch (Exception ignored) {
- return null;
- }
- }
+ /**
+ * Gets the hardware serial number of this device.
+ *
+ * @return serial number or {@code null} if not available.
+ */
+ private static String getDeviceSerialNumber() {
+ // We're using the Reflection API because Build.SERIAL is only available
+ // since API Level 9 (Gingerbread, Android 2.3).
+ try {
+ return (String) Build.class.getField("SERIAL").get(null);
+ } catch (Exception ignored) {
+ return null;
+ }
+ }
- private static byte[] getBuildFingerprintAndDeviceSerial() {
- StringBuilder result = new StringBuilder();
- String fingerprint = Build.FINGERPRINT;
- if (fingerprint != null) {
- result.append(fingerprint);
- }
- String serial = getDeviceSerialNumber();
- if (serial != null) {
- result.append(serial);
- }
- try {
- return result.toString().getBytes("UTF-8");
- } catch (UnsupportedEncodingException e) {
- throw new RuntimeException("UTF-8 encoding not supported");
- }
- }
+ private static byte[] getBuildFingerprintAndDeviceSerial() {
+ StringBuilder result = new StringBuilder();
+ String fingerprint = Build.FINGERPRINT;
+ if (fingerprint != null) {
+ result.append(fingerprint);
+ }
+ String serial = getDeviceSerialNumber();
+ if (serial != null) {
+ result.append(serial);
+ }
+ try {
+ return result.toString().getBytes("UTF-8");
+ } catch (UnsupportedEncodingException e) {
+ throw new RuntimeException("UTF-8 encoding not supported");
+ }
+ }
} \ No newline at end of file