Curve Security - Restrict to Authorized Clients Only

[jasondalycan]

When reviewing the following example code on utilizaing Curve to secure sockets in Node.js it appears that all clients are authenticated:

https://github.com/zeromq/zeromq.js/blob/master/test/unit/socket-curve-send-receive-test.ts

It appears that clients cannot be restricted by client identifier. How can this be done (i.e. allow only authorized clients).