[en] Monitoring agencies often use computer based equipment to control instruments and to collect data at sites that are being monitored under international safeguards or other cooperative monitoring agreements. In order for this data to be used as an independent verification of data supplied by the host at the facility, the software used must be trusted by the monitoring agency. The monitoring party must be sure that the software has not be altered to give results that could lead to erroneous conclusions about nuclear materials inventories or other operating conditions at the site. The host might also want to verify that the software being used is the software that has been previously inspected in order to be assured that only data that is allowed under the agreement is being collected. A description of a method to provide this verification using keyed has functions and how the proposed method overcomes possible vulnerabilities in methods currently in use such as loading the software from trusted disks is presented. The use of public key data authentication for this purpose is also discussed