HashiCorp Vault is a secrets management platform designed to replace the pattern of static, long-lived credentials scattered across configuration files, environment variables, and CI pipelines with a centralised, policy-enforced, fully audited secrets API. Its core abstraction is that every secret has an identity (a path), an owner (determined by an auth method), a policy (an HCL HashiCorp Configuration Language document granting access to specific paths), and a lease (a TTL after which the secret expires or must be renewed). Nothing in Vault is persistent by default — every access is authenticated, every secret access is logged to an immutable audit trail, and credentials that are no longer needed expire automatically rather than accumulating indefinitely.
KMS v2 (Kubernetes KMS Provider version 2) is the stable (GA since Kubernetes 1.29, KMS v1 deprecated in 1.28 and disabled by default in 1.29) mechanism for encrypting the contents of the Kubernetes etcd datastore at rest using an external key management service. Without encryption, Kubernetes Secrets stored in etcd are base64-encoded — trivially decodable by anyone with read access to the etcd data files or a snapshot. With KMS v2 enabled, resources written to etcd — Secrets, ConfigMaps, and any other API objects selected by the EncryptionConfiguration — are encrypted before being persisted, using a unique per-object key derived locally. The envelope encryption scheme means those per-object keys are never stored in plaintext: only their encrypted form lives in etcd, and only the external KMS holds the wrapping key. The encryption configuration is declared in a file referenced by the API server’s --encryption-provider-config flag, with kms: apiVersion: v2 selecting the KMS v2 code path, and endpoint: unix:///path/to/plugin.sock pointing at the plugin’s Unix domain socket.
A Hardware Security Module (HSM) is a purpose-built, tamper-resistant hardware device that holds cryptographic keys and performs cryptographic operations — signing, encryption, decryption, random number generation — entirely within its own protected boundary. The defining property is that private keys generated inside an HSM never exist in plaintext outside it: operations that need the key are sent into the HSM and the result is returned, but the key material itself cannot be extracted. This property is enforced both logically (the firmware refuses export in plaintext) and physically (the device detects and responds to tampering by erasing key material before an attacker can read it). HSMs come in several physical forms: network-attached appliances (rack-mounted devices accessed over the network by many clients), PCIe cards (embedded in a server), and compact USB devices for lower-throughput use cases like protecting CA root keys offline.
