* Add CLUSTER_SIGNING_DURATION environment variable to cluster ([#52497](https://github.com/kubernetes/kubernetes/pull/52497), [@jcbsmpsn](https://github.com/jcbsmpsn))
    * configuration scripts to allow configuration of signing duration of
    * certificates issued via the Certificate Signing Request API.

* kube-apiserver: the OpenID Connect authenticator can now verify ID Tokens signed with JOSE algorithms other than RS256 through the --oidc-signing-algs flag. ([#58544](https://github.com/kubernetes/kubernetes/pull/58544), [@ericchiang](https://github.com/ericchiang))

* Add CLUSTER_SIGNING_DURATION environment variable to cluster ([#52497](https://github.com/kubernetes/kubernetes/pull/52497), [@jcbsmpsn](https://github.com/jcbsmpsn))
    * configuration scripts to allow configuration of signing duration of
    * certificates issued via the Certificate Signing Request API.

- Kubeadm: warn but do not error out on missing "ca.key" files for root CA, front-proxy CA and etcd CA, during "kubeadm join --control-plane" if the user has provided all certificates, keys and kubeconfig files which require signing with the given CA keys. ([#94988](https://github.com/kubernetes/kubernetes/pull/94988), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]

### Other (Cleanup or Flake)

### SIG Auth

- TokenRequest and TokenRequestProjection are now beta features. To enable these feature, the API server needs to be started with the `--service-account-issuer`, `--service-account-signing-key-file`, and `--service-account-api-audiences` flags.
([#67349](https://github.com/kubernetes/kubernetes/pull/67349), [@mikedanese](https://github.com/mikedanese))

- Kubeadm: warn but do not error out on missing "ca.key" files for root CA, front-proxy CA and etcd CA, during "kubeadm join --control-plane" if the user has provided all certificates, keys and kubeconfig files which require signing with the given CA keys. ([#94988](https://github.com/kubernetes/kubernetes/pull/94988), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]

### Other (Cleanup or Flake)

* Removed alpha functionality that allowed the controller manager to approve kubelet server certificates. This functionality should be replaced by automating validation and approval of node server certificate signing requests. ([#62471](https://github.com/kubernetes/kubernetes/pull/62471), [@mikedanese](https://github.com/mikedanese))

#### Graduated to Stable/GA

- The kube-controller-manager managed signers can now have distinct signing certificates and keys.  See the help about `--cluster-signing-[signer-name]-{cert,key}-file`.  `--cluster-signing-{cert,key}-file` is still the default. ([#90822](https://github.com/kubernetes/kubernetes/pull/90822), [@deads2k](https://github.com/deads2k)) [SIG API Machinery, Apps and Auth]

- The kube-controller-manager managed signers can now have distinct signing certificates and keys.  See the help about `--cluster-signing-[signer-name]-{cert,key}-file`.  `--cluster-signing-{cert,key}-file` is still the default. ([#90822](https://github.com/kubernetes/kubernetes/pull/90822), [@deads2k](https://github.com/deads2k)) [SIG API Machinery, Apps and Auth]

### Other notable changes

* The kube-apiserver --service-account-key-file option can be specified multiple times, or can point to a file containing multiple keys, to enable rotation of signing keys. ([#34029](https://github.com/kubernetes/kubernetes/pull/34029), [@liggitt](https://github.com/liggitt))