code: private boolean verifyFingreprint() {
  
          try {
              PackageInfo info = context
                      .getPackageManager()
                      .getPackageInfo(NOKIA_INSTALLER, PackageManager.GET_SIGNATURES);
  
              if (info.signatures.length == 1) {
                  byte[] cert = info.signatures[0].toByteArray();
                  MessageDigest digest;
                  digest = MessageDigest.getInstance("SHA1");
                  byte[] ENABLER_FINGERPRINT = digest.digest(cert);
                  byte[] EXPECTED_FINGERPRINT = hexStringToByteArray(EXPECTED_SHA1_FINGERPRINT);
  
                  if (Arrays.equals(ENABLER_FINGERPRINT, EXPECTED_FINGERPRINT)) {
                      Logger.i("isBillingAvailable", "NIAP signature verified");
                      return true;
                  }
              }
          } catch (NoSuchAlgorithmException e) {
              e.printStackTrace();
          } catch (PackageManager.NameNotFoundException e) {
              e.printStackTrace();
          }
          return false;
      }
docs: Checks SHA1 fingerprint of the enabler
  
  @return true if signature matches, false if package is not found or signature does not match.