I respectfully disagree. While some cryptographic primitives are surely based on some sound math, building cryptographic systems is very hard, and when built, they ane not generally proven to be correct. Some attacks involve influencing source of randomness, whereas proofs simply assume random unguessable numbers, for example. You correctly mention unintended degradation, that is another pretty serious concern, but even when built first, most systems are incorrect, faulty and unsafe.

Proving systems to be correct in computer science is far from settled matter.