Views:
Any bucket created by FSS will always be encrypted using KMS.
For customer-provided buckets, FSS does not modify the existing encryption settings. The bucket will continue using whatever encryption configuration it already has:
  • If the bucket is already encrypted with KMS (either an AWS-managed key or a customer-managed key), it will remain KMS-encrypted.
  • If the bucket is not encrypted with KMS, FSS will not enable KMS encryption for it.

Configuration bucket

The S3 configuration bucket is always encrypted with KMS by FSS.

Quarantine, Clean, and Failure buckets

For the Quarantine, Clean, and Failure buckets:
  • If you enable the feature but do not provide your own buckets, FSS creates the buckets and enables KMS encryption on them.
  • If you provide your own buckets, FSS does not modify the bucket encryption settings.

FSS - KMS encryption behaviour

Scenario
FSS behaviour
Bucket newly created by FSS
FSS enables KMS encryption
Existing bucket previously created by FSS without KMS encryption
FSS enables KMS encryption
Customer-provided bucket without KMS encryption
FSS does not enable KMS encryption
Customer-provided bucket encrypted with an AWS-managed KMS key
FSS does not modify encryption settings, and the customer does not need to provide a key ARN
Customer-provided bucket encrypted with a customer-managed KMS key (CMK)
FSS does not modify encryption settings, and the customer must specify the key ARNs in the KMSKeyARNsForBucketSSE parameter. The specified key ARNs will be attached to the related Lambda execution role permissions.