signature apk check in runtime

signature_check

    PackageInfo info = null;
        try {
            info = getPackageManager().getPackageInfo(getPackageName(), PackageManager.GET_SIGNATURES);
            for (Signature signature : info.signatures) {
                MessageDigest md = null;
                try {
                    md = MessageDigest.getInstance("SHA");
                    md.update(signature.toByteArray());

                    if (!Base64.encodeToString(md.digest(), Base64.DEFAULT).equals("sha sign key")) {
                      //dont match sign key with current app
                    }
                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                }
            }

        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }