Diffie-Hellman Key Exchange in a Quantum World

In 1976, the foundations of our modern cybersecurity infrastructure were created with the publication of the Diffie-Hellman key exchange method:

Within the paper, Whitfield Diffie proposed a fundamental advancement in the usage of public key encryption and Marty Hellman laid out a method of using discrete logarithms to create a shared secret between Bob and Alice:

It was just magic, and although we now use elliptic curves instead of discrete logarithms, it is still at the heart of virtually every connection that we make to the Internet. However, quantum computers could put an end to it, as it is not so easy to implement the method using most of the new Post Quantum robust methods. Only the isogeny-based methods — such as with SIKE — support a DH-type of key exchange. Unfortunately, the version of SIKE submitted to the NIST PQC competition was cracked, and it is not now being considered for standardization. The new standards, though, use a KEM (Key Encapsulation Method), and where Alice sends Bob her public…