Trust engineering: rejecting the tyranny of the weakest link

In 2002 [1], the National Security Agency's Information Assurance Research Group coined the term, trust engineering, to describe a methodology for making use of software of uncertain provenance in mission-critical systems. Today, the loss of control that made software so hard to trust then applies to the rest of the supply chain as well. The discipline we described in the internal paper, Trust-engineering: An Assurance Strategy for Software-based Systems, no longer seems heretical today, even at NSA. Ten years later, we revisit the principles of trust engineering, compare the mechanisms available to us today with the practices of the past, and explore the construction of systems that are stronger than their weakest link.