PQC and Symmetric Key in Perfect Harmony

The Power of Public Key and the Speed of Symmetric Key

Like it or not, our cybersecurity love affair with RSA and ECC will have to come to an end. They have served us well for many decades, but in a world of quantum computers, they are not hard problems anymore. So, our love of ECDH for key exchange methods will have to be dropped and replaced with ML-KEM (aka Kyber).

Luckily, AES-256 can stand up to quantum cracking and will continue to be the encryption method of choice for our files and data streams. If we want, we can use ML-KEM as a key exchange method and also as an encryption method; where we now define it as key encapsulation. With this, Bob will take Alice’s public key (pk) and encapsulate a message into a ciphertext. He will then pass the ciphertext to Alice, and she will decrypt it with her private key (sk):

This process will thus replace the Diffie-Hellman key exchange that we perform at the present time with ECDH. But, we can also use the power of the key encapsulation method of using the public key to pass the key with symmetric key encryption and thus create hybrid encryption.