Cryptography after the Aliens Land

 Currently number theory–based encryption, which is what our modern public-key systems are, seems relatively safe in the quantum computing environment.

Grover's algorithm shows that quantum computer speeds up attacks to halve the key length. This would mean that a 256-bit key is as strong against a quantum computer as a 128-bit key is against a conventional computer.
On the other hand, quantum computing is rapidly evolving. There might be many surprises along the way. This is a great paper by the cybersecurity guru Bruce Schneier.
"Cryptography after the Aliens Land," in IEEE Security & Privacy, vol. 16, no. 5, pp. 86-88, September/October 2018 #cryptography #quantumcomputing #cybersecurity