Measurement Digital Watermarking for Automated Test System Data Integrity

Standard cyber security practices that help to protect data's integrity while at rest, transit, and processing are susceptible to insider threats. In order to resist these insider threat vulnerabilities the data must be verifiable. One way to verify the integrity of Automated Test System (ATS) test results is to use measurement digital watermarking. This method is particularly appropriate to ATS test results because test reports are usually unencrypted when saved and printed.Measurement digital watermarking embeds identifying verification data in available locations within the test result stored data. The identifying verification data is developed using hash functions with dynamic salting. The available locations are found in the insignificant digits of analog measurements. In addition, a method of digitally watermarking test reports consisting of all digital tests by using font variation is described.Using these techniques does not protect test results from tampering but it does allow for detection of tampering and invalid test results. Since ATS results are used in determining avionics airworthiness the integrity of the results is an important component of aviation safety.