public String getSignature() {

        String result = "";

        Signature[] sigs = new Signature[0];
        try {
            sigs = getPackageManager().getPackageInfo(getPackageName(), PackageManager.GET_SIGNATURES).signatures;
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }
        if(sigs.length > 0)
            result = sigs[0].toCharsString();

        return result;
    }

    public static String getDateCompilation() {

        String date = "";

        try {
            ApplicationInfo ai = getPackageManager().getApplicationInfo(getPackageName(), 0);
            ZipFile zf = new ZipFile(ai.sourceDir);
            ZipEntry ze = zf.getEntry("classes.dex");
            long time = ze.getTime();
            SimpleDateFormat SQLiteDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            date = new StringBuilder(SQLiteDateFormat.format(time)).toString();
            zf.close();
        } catch (Exception e) {
        }

        return date;
    }