ServerSideEncryptionByDefault

Describes the default server-side encryption to apply to new objects in the bucket. If a PUT Object request doesn't specify any server-side encryption, this default encryption will be applied. If you don't specify a customer managed key at configuration, Amazon S3 automatically creates an Amazon Web Services KMS key in your Amazon Web Services account the first time that you add an object encrypted with SSE-KMS to a bucket. By default, Amazon S3 uses this KMS key for SSE-KMS. For more information, see PUT Bucket encryption in the Amazon S3 API Reference.