Key Management Server

The vCenter Server requests keys from an external KMS. The KMS generates and stores the keys, and passes them to vCenter Server for distribution.
You can use the vSphere Web Client or the vSphere API to add a cluster of KMS instances to the vCenter Server system. If you use multiple KMS instances in a cluster, all instances must be from the same vendor and must replicate keys.
If your environment uses different KMS vendors in different environments, you can add a KMS cluster for each KMS and specify a default KMS cluster. The first cluster that you add becomes the default cluster. You can explicitly change the default later.
As a KMS client, vCenter Server uses the Key Management Interoperability Protocol (KMIP) and makes it easy to use the KMS of your choice.