SecurityWard.java

public class SecurityWard {


    private static final String CLASS_TAG = "SecurityWard";
    private static final String CERTIFICATE_SHA1 = "";

    /**
     * Detect if Google Play Store was the installer
     * @param context Current context
     * @return true if was installed with Google Play Store
     */
    public static boolean checkGooglePlayStore (Context context) {
        String installerPackageName = context.getPackageManager().getInstallerPackageName(context.getPackageName());
        return installerPackageName != null && installerPackageName.startsWith("com.google.android");
    }

    /**
     * Detect if it runs on an emulator
     * @return true if the app it's running on a emulator
     */
    public static boolean isEmulator(){
        try {

            Class systemPropetyClazz = Class.forName("android.os.SystemProperties");

            boolean kernelQemu = getProperty(systemPropetyClazz, "ro.kernel.qemu").length() > 0 ;
            boolean hardwareGoldfish = getProperty(systemPropetyClazz, "ro.hardware").equals("goldfish");
            boolean modelSdk = getProperty(systemPropetyClazz, "ro.product.model").equals("sdk");

            if (kernelQemu || hardwareGoldfish || modelSdk){
                return true;
            }

        } catch (Exception e) {
            LogManager.log(LogManager.ERROR,CLASS_TAG,"isEmulator",e.toString());
        }

        return false;
    }

    private static String getProperty (Class clazz, String propertyName) throws Exception {
        return (String) clazz.getMethod("get", new Class[] {String.class}).invoke(clazz, new Object[] {propertyName});
    }

    /**
     * Detect if the app has the debuggable  flag enabled
     * @param context Current context
     * @return true if it's enabled
     */
    public static boolean isDebuggable (Context context){
        return (context.getApplicationInfo().flags & ApplicationInfo.FLAG_DEBUGGABLE) != 0;
    }

    /**
     *  Detects if the current signature matches the original one
     *  @param context Current context
     *  @return true if the signatures match each other
     */
    public static boolean validateAppSignature(Context context) {
        try {
            //get the signature from the package manager
            PackageInfo packageInfo = context.getPackageManager().getPackageInfo(context.getPackageName(), PackageManager.GET_SIGNATURES);
            Signature[] appsSignatures = packageInfo.signatures;

            //this sample only checks the first certificate
            for (Signature signature : appsSignatures){
                byte[] singnatureBytes = signature.toByteArray();

                //calc sha1 in hex
                String currentSignature = calcSHA1(singnatureBytes);

                //compare signatures
                return CERTIFICATE_SHA1.equalsIgnoreCase(currentSignature);
            }

        }catch (Exception e){
            LogManager.log(LogManager.ERROR,CLASS_TAG,"validateAppSignature",e.toString());
        }

        return false;
    }

    private static String calcSHA1(byte[] signature) throws NoSuchAlgorithmException {
        MessageDigest digest = MessageDigest.getInstance("SHA1");
        digest.update(signature);
        byte[] signatureHash = digest.digest();
        return bytesToHex(signatureHash);
    }

    public static String bytesToHex (byte[] bytes){
        final char[] hexArray = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
        char[] hexChars = new char[bytes.length * 2];
        int v;
        for (int j=0;j<bytes.length;j++){
            v = bytes[j] & 0xFF;
            hexChars[j * 2] = hexArray[v >>> 4];
            hexChars[j * 2 + 1] = hexArray[v & 0x0F];
        }
        return  new String(hexChars);
    }

}