Using ssh-keygen from WSL to generate an SSH key

SSH keys are useful to enable access to networked resources.  

The command ssh-keygen (the OpenSSH authentication key utilit) can be used to generate keys.

Example usage:  ssh-keygen -t ed25519 -C "myemail@mydomain.com".  

The -t option signifies type, and ed25519 refers to the algorithm based on Elliptic Curve Cryptography using an Edwards curve (the recommended default - it competes with RSA which is needed for compatibility with older systems). The -C flag provides a new comment. 

What gets generated is actually a pair of keys, a private key (stored locally) and a public key (stored on the server, but reference copy is typically stored locally too, in your .ssh directory).  It is an asymmetric authentication (not encryption) protocol.

info ssh-keygen will help you decode other command line options for generating keys.

The generated keys are stored in ~/.ssh.

Elliptic Curves Assert Presence on Linux

WinJoes may be surprised to see refs to elliptic curves appearing in their Linux VMs in their D2D Ops.

These appearances often reference EdDSA (e.g. in messages like "using EDDSA key 0327BE68.....").

EdDSA refers to the Edwards-curve Digital Signature Algorithm (EdDSA) in public key cryptography.

Edwards curves are an artefact of algebraic geometry and named after the American mathematician Harold Edwards.  The specific form of Edwards curves used in the algorithm are known as twisted Edwards curves, where the "twist" comes from a non-unitary coefficient (from some field F) in the curve equation. The twisted Edwards curve equation is an interesting equation and the first question when you see it is how did someone come up with it.