It is possible to prove software adheres to a certain specification. This is time consuming, and how feasible it is depends a lot on how your specification was

It is possible to prove software adheres to a certain specification. This is time consuming, and how feasible it is depends a lot on how your specification was written. It generally also depends on how your software was written. The big issue is that writing a useful specification can be hard. Especially if you want to also make the specification easy to check. A side issue is that your proof will make assumptions about how a computer works that are simplified.