* Fixed the webhook admission plugin so that webhook author could use the DNS name of the service as the CommonName when generating the server cert for the webhook.
    * Action required:

GMT0 Greenwich HST Hongkong Iceland Indian/Antananarivo Indian/Chagos Indian/Christmas Indian/Cocos Indian/Comoro Indian/Kerguelen Indian/Mahe Indian/Maldives Indian/Mauritius Indian/Mayotte Indian/Reunion Iran Israel Jamaica Japan Kwajalein Libya MET MST MST7MDT Mexico/BajaNorte Mexico/BajaSur Mexico/General NZ NZ-CHAT Navajo PRC PST8PDT Pacific/Apia Pacific/Auckland Pacific/Bougainville Pacific/Chatham Pacific/Chuuk Pacific/Easter Pacific/Efate Pacific/Enderbury Pacific/Fakaofo Pacific/Fiji Pacific/Funafuti...

    * Fixed the webhook admission plugin so that webhook author could use the DNS name of the service as the CommonName when generating the server cert for the webhook.
    * Action required:

pull/57902), [@kawych](https://github.com/kawych))

* On cluster provision or upgrade, kubeadm now generates certs and secures all connections to the etcd static-pod with mTLS. This includes the etcd serving cert, the etcd peer cert, and the apiserver etcd client cert. Flags and hostMounts are added to the etcd and apiserver static-pods to load these certs. For connections to etcd, https is now used in favor of http. ([#57415](https://github.com/kubernetes/kubernetes/pull/57415), [@s...

* kubeadm: add back `--cert-dir` option for `kubeadm init phase certs sa` ([#73239](https://github.com/kubernetes/kubernetes/pull/73239), [@mattkelly](https://github.com/mattkelly))

- The CSR signing cert/key pairs will be reloaded from disk like the kube-apiserver cert/key pairs ([#86816](https://github.com/kubernetes/kubernetes/pull/86816), [@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]

- kubeadm still generates RSA keys when deploying a node, but also accepts ECDSA
keys if they already exist in the directory specified in the `--cert-dir` option. ([#76390](https://github.com/kubernetes/kubernetes/pull/76390), [@rojkov](https://github.com/rojkov))

  Beta feature in 1.27. ([#114445](https://github.com/kubernetes/kubernetes/pull/114445), [@mengjiao-liu](https://github.com/mengjiao-liu))
- `Secret` of `kubernetes.io/tls` type now verifies that the private key matches the cert ([#113581](https://github.com/kubernetes/kubernetes/pull/113581), [@aimuz](https://github.com/aimuz))

- The `kubelet` now reports distinguishes log messages about certificate rotation for its client cert and server cert separately to make debugging problems with one or the other easier. ([#101252](https://github.com/kubernetes/kubernetes/pull/101252), [@smarterclayton](https://github.com/smarterclayton))