Encryption methods that cannot be cracked with quantum computers. Experts contend it is only a matter of time before quantum computers will be able to break all current cryptographic coding systems, namely the Rivest-Shamir-Adleman (RSA), Diffie-Hellman and elliptic curve (ECC) methods. Quantum-safe techniques are being devised, and such methods will have to be in place in government and private industry when the time comes that a quantum computer renders today's encryption systems worthless. That day has been called "Q-Day."
Encryption algorithms today are quantum resistant in varying degrees. Although AES-128 is considered by the National Institute of Standards & Technology (NIST) to be weak, AES-192 and AES-256 are defined as stronger and strongest (AES-192 is "probably secure" for the time being). The larger number of bits in the key is the criterion. See quantum computing
, quantum cryptography
and elliptic curve cryptography
The Title Says It All
"Cryptography Apocalypse" by Roger Grimes is likely the best book ever written about quantum computing and its ramifications. Not only does Grimes delve into the security aspects, he covers the subject in a manner that is understandable for most people.