public static void printHashKey (Context pContext){
   try {
       PackageInfo info = pContext.getPackageManager().getPackageInfo(pContext.getPackageName(),
               PackageManager.GET_SIGNATURES);
       for (Signature signature : info.signatures) {
           MessageDigest md = MessageDigest.getInstance("SHA");
           md.update(signature.toByteArray());
           String hashKey = new String(Base64.encode(md.digest(), 0));
   }
       } catch (PackageManager.NameNotFoundException e) {
       e.printStackTrace();
   } catch (NoSuchAlgorithmException e) {
       e.printStackTrace();
   }
}