Knot DNS 2.1 introduced support for DNSSEC signing using PKCS #11. PKCS #11 (also called Cryptoki) is a standard interface to access various Hardware Security Modules (HSM). Such devices are usually used to improve protection of private key material. The interface is rather flexible and gives the HSM vendors huge amount of freedom, which unfortunately makes its use a bit tricky. There are often surprising differences between individual implementations.

Every Kubernetes cluster has a cluster root Certificate Authority (CA). The CA is generally used by cluster components to validate the API server’s certificate, by the API server to validate kubelet client certificates, etc. To support this, the CA certificate bundle is distributed to every node in the cluster and is distributed as a secret attached to default service accounts. Optionally, your workloads can use this CA to establish trust. Your application can request a certificate signing using the certificates.k8s.io API using a protocol that is similar to the ACME draft.