Supersingular Isogeny Diffie–Hellman (SIDH) key exchange
When Bob and Alice Went For A Walk (But not together!)
Let’s send Bob and Alice out for a walk — separately (as they may be self isolating). Let’s start them at the same place, and let each of them take a random walk, and share their locations. Then let them take the same random walk, and they should end up together in the same place — and no-one will be able to know where they are!
The next decade will bring a complete change, and where we see RSA leave the stage, and where there will be severe warnings on the robustness of ECC (Elliptic Curve Cryptography). The new implementations of tunnelling methods will see a rise in the quantum robust techniques, and these will give us alternatives to ECC, while highlighting that we need to have a migration path.
And so we are in a phase of coming up with new puzzles which will allow us to sustain our public key encryption methods, and which will not be easily broken by quantum computers. One of the methods proposed for key exchange is Supersingular isogeny Diffie–Hellman key exchange (SIDH). So let’s try and explain its basic operation, in a simple way.
