Well, the PKI (Public Key Infrastructure) has had a good run for its money, but with our quantum migration, our digital certificates are going to get much larger. This involves X.509 certificates holding more than one public key (the classical one and the quantum robust one), and also the possibility of having to dual-sign the certificate. But, Google Chrome has a new plan which would do away with certificates all together, and basically publish a Merkle root hash. This hash value would then cover all the existing certificates that have been published.
Why change?
Our existing X.509 certificates contain either RSA or ECC public keys, and are signed by these methods. Unfortunately, using Shor’s algorithm, quantum computers will be able to break these methods. For this, NIST has defined a range of new standards for digital signatures, including ML-DSA, FN-DSA and SLH-DSA (SPHINCS+). For key sizes, we typically get equivalent levels to 128-bit security (Level 1), 192-bit security (Level 3) and 256-bit security (Level 5). Unfortunately, ML-DSA has much larger public key and signature sizes than RSA and ECC, with ML-DSA-65 having a public key size of 1,592 bytes and a signature size of 3,293 bytes. This is much larger than RSA with a public key and signature size of 256 bytes, and for ECC with a public key of 64 bytes:
Method Public…
