renaming eu.siacs.conversations to de.thedevstack.conversationsplus

 "renaming eu.siacs.conversations to de.thedevstack.conversationsplus"

package renaming completed

1 files changed, 327 insertions, 0 deletions

diff --git a/src/main/java/de/thedevstack/conversationsplus/utils/PRNGFixes.java b/src/main/java/de/thedevstack/conversationsplus/utils/PRNGFixes.java
new file mode 100644
index 00000000..78776aeb
--- /dev/null
+++ b/src/main/java/de/thedevstack/conversationsplus/utils/PRNGFixes.java
@@ -0,0 +1,327 @@
+package de.thedevstack.conversationsplus.utils;
+
+import android.os.Build;
+import android.os.Process;
+import android.util.Log;
+
+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;
+
+/**
+ * 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.
+				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());
+			}
+
+			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");
+		}
+	}
+}
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