When an envelope transformer calls out to KMS (for instance), it will be
very helpful to pass a `context.Context` to allow for cancellation. This
patch does that, while passing the previously-expected additional data
via a context value.
Signed-off-by: Steve Kuznetsov <skuznets@redhat.com>
Kubernetes-commit: 27312feb9983c18d1daf00afba788727d024cdd0
Tweak the ValueTransformer interface slightly to support additional
context information (to allow authenticated data to be generated by the
store and passed to the transformer). Add a prefix transformer that
looks for known matching prefixes and uses them. Add an AES GCM
transformer that performs AEAD on the values coming in and out of the
store.
Kubernetes-commit: f418468c87d3071c5d9ed14ce850996c77251080
Anish Ramasekar
Steve Kuznetsov
Clayton Coleman