Talk:EVP Key Derivation
About this page
It should be noted that ever since this page got filled in with examples and all that, it strictly talks about upcoming functionality. The EVP_KDF API doesn't exist in any current release (and hasn't reached its final form yet), but will be part of the upcoming 3.0 release. It's therefore to be expected that the example shown on this page will change as the API evolves.
This is the gist of my direct comment. The ctrl APIs were transient, we're migrating to OSSL_PARAM based ones globally -- it's just going to take a while.