In contrast to symmetric-key algorithms, key encapsulation mechanisms in use today are easily broken by quantum computers.

Public-key algorithms are important too. They help get around the fundamental drawback of symmetric-key encryption, which is that you need a secure way to share symmetric keys in the first place.

ASC X9 has released a new standard, X9.24-3, that allows the use of the AES DUKPT algorithm to enhance security in retail financial transactions.

Shared secrets generated by a KEM can then be used with symmetric-key cryptographic operations, which aren’t vulnerable to Shor’s algorithm when the keys are of a sufficient size.

Proponents believe hybrid encryption compensates for weaknesses in single post-quantum algorithms, but performance, complexity, and security concerns remain.