- Kubeadm: add support for certificate chain validation. When using kubeadm in external CA mode, this allows an intermediate CA to be used to sign the certificates. The intermediate CA certificate must be appended to each signed certificate for this to work correctly. ([#97266](https://github.com/kubernetes/kubernetes/pull/97266), [@robbiemcmichael](https://github.com/robbiemcmichael)) [SIG Cluster Lifecycle]

For detailed release notes on the three alpha features from SIG AWS, please refer to the following Changelogs:

(The jury all brightened up again.)

  `Please your Majesty,' said the Knave, `I didn't write it, and
they can't prove I did:  there's no name signed at the end.'

  `If you didn't sign it,' said the King, `that only makes the
matter worse.  You MUST have meant some mischief, or else you'd
have signed your name like an honest man.'

  There was a general clapping of hands at this:  it was the

- Addressed an issue where a JWT authenticator set up via `--authentication-config` would encounter failures in verifying tokens not signed with RS256. ([#123282](https://github.com/kubernetes/kubernetes/pull/123282), [@enj](https://github.com/enj))

  - The requested name did not match the set of authorized names (`x509.HostnameError`)
  - The error surfaced after attempting a connection contained one of the substrings: "certificate is not trusted" or "certificate signed by unknown authority". ([#120736](https://github.com/kubernetes/kubernetes/pull/120736), [@MadhavJivrajani](https://github.com/MadhavJivrajani))

* 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))

- Kubeadm: during execution of the "check expiration" command, treat the etcd CA as external if there is a missing etcd CA key file (etcd/ca.key) and perform the proper validation on certificates signed by the etcd CA. Additionally, make sure that the CA for all entries in the output table is included - for both certificates on disk and in kubeconfig files. ([#106925](https://github.com/kubernetes/kubernetes/pull/106925), [@neolit123](https://gi...

- 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,...

- 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,...

- kube-controller-manager currently needs a writable `--cert-dir` (default is `/var/run/kubernetes`) for generating self-signed certificates, when no `--tls-cert-file` or `--tls-private-key-file` are provided.