aboutsummaryrefslogtreecommitdiffstats
path: root/src/main/java/de/thedevstack/conversationsplus/utils/PRNGFixes.java
diff options
context:
space:
mode:
Diffstat (limited to 'src/main/java/de/thedevstack/conversationsplus/utils/PRNGFixes.java')
-rw-r--r--src/main/java/de/thedevstack/conversationsplus/utils/PRNGFixes.java328
1 files changed, 0 insertions, 328 deletions
diff --git a/src/main/java/de/thedevstack/conversationsplus/utils/PRNGFixes.java b/src/main/java/de/thedevstack/conversationsplus/utils/PRNGFixes.java
deleted file mode 100644
index 0751809c..00000000
--- a/src/main/java/de/thedevstack/conversationsplus/utils/PRNGFixes.java
+++ /dev/null
@@ -1,328 +0,0 @@
-package de.thedevstack.conversationsplus.utils;
-
-import android.os.Build;
-import android.os.Process;
-
-import java.io.ByteArrayOutputStream;
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.OutputStream;
-import java.io.UnsupportedEncodingException;
-import java.security.NoSuchAlgorithmException;
-import java.security.Provider;
-import java.security.SecureRandom;
-import java.security.SecureRandomSpi;
-import java.security.Security;
-
-import de.thedevstack.android.logcat.Logging;
-
-/**
- * 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();
-
- /** 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 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());
-
- // 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;
- }
-
- // 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());
- }
-
- 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 {
-
- 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 {
-
- /*
- * 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 Object sLock = new Object();
-
- /**
- * 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;
-
- /**
- * 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.
- Logging.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());
- }
-
- 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;
- }
-
- 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;
- }
- }
- }
-
- /**
- * 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;
- }
- }
-
- 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
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-02 12:51:26 +0000