The capabilities of quantum computing have already been proven by factoring primes. Check out this article showing the highest number factored with a quantum computer and shor's algorithm. Shor's algorithm can be used to break RSA encryption, the only thing we are lacking is a quantum computer with 256+ bits.

So will everything break when quantum computers have more bits and are widely accessible? There are already solutions proposed that make blockchains and other technologies relying on encryption "quantum-proof" so I think we will be fine.

While it is possible that there is a back-door is SHA, I find it very unlikely. The algorithm is open source and reviewed by academic communities who have looked for back-doors. Those "strange parameters" are probably large primes that the algorithm needs to simulate randomness in a deterministic way. Check out this video if you want to learn more about how SHA works.

And while I agree that it is easy to be skeptical of quantum mechanics while living in the macro world, there is enough science to convince me of the quantum nature of our reality. So why aren't we, as macro objects, effected by quantum mechanics? I heard it explained like this. Quantum objects are flying around in superposition until they are measured. A measurement could be a collision with a photon or other particle. The reason that macro objects are not subjected to the uncertainty of the quantum world is that we are constantly being measured. Think about how many photons are bouncing off you at this instant then thank the photons for your certainty.

Thoughts?