rwestergren · November 1, 2020 10:30 · Dec 8, 2015 · Dec 8, 2015
diff --git a/Main.java b/Main.java
@@ -0,0 +1,153 @@
+import java.io.IOException;
+import java.io.InputStream;
+import java.lang.ref.WeakReference;
+import java.security.cert.CertificateEncodingException;
+import java.util.Enumeration;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class Main {
+
+    private static final Object mSync = new Object();
+    private static WeakReference<byte[]> mReadBuffer;
+
+    public static void main(String[] args) {
+        if (args.length < 1) {
+            System.out.println("Usage: java -jar GetAndroidSig.jar <apk/jar>");
+            System.exit(-1);
+        }
+
+        System.out.println(args[0]);
+
+        String mArchiveSourcePath = args[0];
+
+        WeakReference<byte[]> readBufferRef;
+        byte[] readBuffer = null;
+        synchronized (mSync) {
+            readBufferRef = mReadBuffer;
+            if (readBufferRef != null) {
+                mReadBuffer = null;
+                readBuffer = readBufferRef.get();
+            }
+            if (readBuffer == null) {
+                readBuffer = new byte[8192];
+                readBufferRef = new WeakReference<byte[]>(readBuffer);
+            }
+        }
+
+        try {
+            JarFile jarFile = new JarFile(mArchiveSourcePath);
+            java.security.cert.Certificate[] certs = null;
+
+            Enumeration entries = jarFile.entries();
+            while (entries.hasMoreElements()) {
+                JarEntry je = (JarEntry) entries.nextElement();
+                if (je.isDirectory()) {
+                    continue;
+                }
+                if (je.getName().startsWith("META-INF/")) {
+                    continue;
+                }
+                java.security.cert.Certificate[] localCerts = loadCertificates(jarFile, je, readBuffer);
+                if (false) {
+                    System.out.println("File " + mArchiveSourcePath + " entry " + je.getName()
+                            + ": certs=" + certs + " ("
+                            + (certs != null ? certs.length : 0) + ")");
+                }
+                if (localCerts == null) {
+                    System.err.println("Package has no certificates at entry "
+                            + je.getName() + "; ignoring!");
+                    jarFile.close();
+                    return;
+                } else if (certs == null) {
+                    certs = localCerts;
+                } else {
+                    // Ensure all certificates match.
+                    for (int i = 0; i < certs.length; i++) {
+                        boolean found = false;
+                        for (int j = 0; j < localCerts.length; j++) {
+                            if (certs[i] != null
+                                    && certs[i].equals(localCerts[j])) {
+                                found = true;
+                                break;
+                            }
+                        }
+                        if (!found || certs.length != localCerts.length) {
+                            System.err.println("Package has mismatched certificates at entry "
+                                    + je.getName() + "; ignoring!");
+                            jarFile.close();
+                            return; // false
+                        }
+                    }
+                }
+            }
+
+            jarFile.close();
+
+            synchronized (mSync) {
+                mReadBuffer = readBufferRef;
+            }
+
+            if (certs != null && certs.length > 0) {
+                final int N = certs.length;
+
+                for (int i = 0; i < N; i++) {
+                    String charSig = new String(toChars(certs[i].getEncoded()));
+                    System.out.println("Cert#: " + i + "  Type:" + certs[i].getType()
+                            + "\nPublic key: " + certs[i].getPublicKey()
+                            + "\nHash code: " + certs[i].hashCode()
+                            + " / 0x" + Integer.toHexString(certs[i].hashCode())
+                            + "\nTo char: " + charSig);
+                }
+            } else {
+                System.err.println("Package has no certificates; ignoring!");
+                return;
+            }
+        } catch (CertificateEncodingException ex) {
+            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
+        } catch (IOException e) {
+            System.err.println("Exception reading " + mArchiveSourcePath + "\n" + e);
+            return;
+        } catch (RuntimeException e) {
+            System.err.println("Exception reading " + mArchiveSourcePath + "\n" + e);
+            return;
+        }
+    }
+
+    private static char[] toChars(byte[] mSignature) {
+        byte[] sig = mSignature;
+        final int N = sig.length;
+        final int N2 = N * 2;
+        char[] text = new char[N2];
+
+        for (int j = 0; j < N; j++) {
+            byte v = sig[j];
+            int d = (v >> 4) & 0xf;
+            text[j * 2] = (char) (d >= 10 ? ('a' + d - 10) : ('0' + d));
+            d = v & 0xf;
+            text[j * 2 + 1] = (char) (d >= 10 ? ('a' + d - 10) : ('0' + d));
+        }
+
+        return text;
+    }
+
+    private static java.security.cert.Certificate[] loadCertificates(JarFile jarFile, JarEntry je, byte[] readBuffer) {
+        try {
+            // We must read the stream for the JarEntry to retrieve
+            // its certificates.
+            InputStream is = jarFile.getInputStream(je);
+            while (is.read(readBuffer, 0, readBuffer.length) != -1) {
+                // not using
+            }
+            is.close();
+
+            return (java.security.cert.Certificate[]) (je != null ? je.getCertificates() : null);
+        } catch (IOException e) {
+            System.err.println("Exception reading " + je.getName() + " in "
+                    + jarFile.getName() + ": " + e);
+        }
+        return null;
+    }
+}