This change updates KMS v2 to not create a new DEK for every
encryption. Instead, we re-use the DEK while the key ID is stable.
Specifically:
We no longer use a random 12 byte nonce per encryption. Instead, we
use both a random 4 byte nonce and an 8 byte nonce set via an atomic
counter. Since each DEK is randomly generated and never re-used,
the combination of DEK and counter are always unique. Thus there
can never be a nonce collision. AES GCM strongly encourages the use
of a 12 byte nonce, hence the additional 4 byte random nonce. We
could leave those 4 bytes set to all zeros, but there is no harm in
setting them to random data (it may help in some edge cases such as
live VM migration).
If the plugin is not healthy, the last DEK will be used for
encryption for up to three minutes (there is no difference on the
behavior of reads which have always used the DEK cache). This will
reduce the impact of a short plugin outage while making it easy to
perform storage migration after a key ID change (i.e. simply wait
ten minutes after the key ID change before starting the migration).
The DEK rotation cycle is performed in sync with the KMS v2 status
poll thus we always have the correct information to determine if a
read is stale in regards to storage migration.
Signed-off-by: Monis Khan <mok@microsoft.com>
Kubernetes-commit: 832d6f0e19f13b9dd22b1fe9d705817e9e64f4f1
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
Monis Khan
Steve Kuznetsov
haoshuwei
Yang Li
Slava Semushin
Clayton Coleman