Acceptance based assurance

Assurance of software systems has traditionally been sought through the rigour of the development process. The higher the assurance, the more demanding the development process; the highest assurance requiring the use of formal methods during development. This approach has been followed for decades with some success, but increased assurance brings a disproportionate increase in cost and risk. A change in emphasis is suggested from the development of a system to its acceptance. The benefits for high assurance systems are illustrated through a case study and preliminary experience of high assurance techniques are reported.