Added XorUpdate utility to help prepare auto-updates.

src/main/java/org/qora/XorUpdate.java

@@ -0,0 +1,58 @@
+package org.qora;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import org.qora.controller.AutoUpdate;
+
+public class XorUpdate {
+
+	private static final byte XOR_VALUE = AutoUpdate.XOR_VALUE;
+
+	public static void main(String args[]) {
+		if (args.length != 2) {
+			System.err.println("usage: XorUpdate <input-file> <output-file>");
+			System.exit(1);
+		}
+
+		Path inPath = Paths.get(args[0]);
+		if (!Files.isReadable(inPath)) {
+			System.err.println(String.format("Cannot open '%s'", args[0]));
+			System.exit(2);
+		}
+
+		Path outPath = Paths.get(args[1]);
+
+		try (InputStream in = Files.newInputStream(inPath); OutputStream out = Files.newOutputStream(outPath)) {
+			byte[] buffer = new byte[1024 * 1024];
+			do {
+				int nread = in.read(buffer);
+				if (nread == -1)
+					break;
+
+				for (int i = 0; i < nread; ++i)
+					buffer[i] ^= XOR_VALUE;
+
+				out.write(buffer, 0, nread);
+			} while (true);
+			out.flush();
+		} catch (IOException e) {
+			System.err.println(e.getLocalizedMessage());
+
+			try {
+				Files.deleteIfExists(outPath);
+			} catch (IOException e1) {
+				System.err.println(e.getLocalizedMessage());
+			}
+
+			System.exit(2);
+		}
+
+		System.exit(0);
+	}
+
+}

src/main/java/org/qora/controller/AutoUpdate.java

@@ -50,7 +50,7 @@ public class AutoUpdate extends Thread {
 	private static final int EXPECTED_DATA_LENGTH = Transformer.TIMESTAMP_LENGTH + GIT_COMMIT_HASH_LENGTH + Transformer.SHA256_LENGTH;
 
 	/** This byte value used to hide contents from deep-inspection firewalls in case they block updates. */
-	private static final byte XOR_VALUE = (byte) 0x5a;
+	public static final byte XOR_VALUE = (byte) 0x5a;
 
 	private static AutoUpdate instance;