What is Software Assurance (SwA) and what are its two key properties?

Software Assurance is confidence that software is free of vulnerabilities and behaves as intended — its two pillars are Trustworthiness and Predictable Execution.

Software Assurance (SwA) is the level of confidence that software is free from vulnerabilities — whether intentionally designed in (a backdoor) or accidentally inserted at any point in its lifecycle — and that it functions in the intended manner.

The two properties are deliberately split because they fail in different ways:

1. Trustworthiness: no weaknesses an attacker (or accident) can exploit. This is the security half — it's about the absence of bad behaviour.
2. Predictable Execution: when you run it, it does exactly what it's supposed to. This is the correctness half — it's about the presence of good behaviour.

Tip: Trustworthy-but-unpredictable (secure yet buggy) and predictable-but-untrustworthy (works perfectly but has a backdoor) are both assurance failures — you need both halves.