Hi , I have a fairly detailed understanding of Quantum Mechanics, Quantum Computing and encryption...
I can confidently tell you that if a functioning Quantum computer is ever created then ALL current encryption would be rendered completely useless.
ALL encrypted files could be unlocked and Blockchains could be completely undone.
MAYBE in the future, someone will develop a kind of Quantum encryption, this would be the only way to keep data secure.
RE: Would a Functioning Quantum Computer Render Encryption Useless?