Data protection and encryption

Your SSE-KMS configuration can only support 1 customer managed key per directory bucket for the lifetime of the bucket. The AWS managed key (aws/s3) isn't supported. Also, after you specify a customer managed key for SSE-KMS, you can't override the customer managed key for the bucket's SSE-KMS configuration.

You can identify the customer managed key you specified for the bucket's SSE-KMS configuration, in the following way:

To use a new customer managed key for your data, we recommend copying your existing objects to a new directory bucket with a new customer managed key.

For Zonal endpoint (object-level) API operations except CopyObject and UploadPartCopy, you authenticate and authorize requests through CreateSession for low latency. We recommend that the bucket's default encryption uses the desired encryption configuration and you don't override the bucket default encryption in your CreateSession requests or PUT object requests. Then, new objects are automatically encrypted with the desired encryption settings. To encrypt new objects in a directory bucket with SSE-KMS, you must specify SSE-KMS as the directory bucket's default encryption configuration with a KMS key (specifically, a customer managed key). Then, when a session is created for Zonal endpoint API operations, new objects are automatically encrypted and decrypted with SSE-KMS and S3 Bucket Keys during the session. For more information about the encryption overriding behaviors in directory buckets, see Specifying server-side encryption with AWS KMS for new object uploads.

In the Zonal endpoint API calls (except CopyObject and UploadPartCopy), you can't override the values of the encryption settings (x-amz-server-side-encryption, x-amz-server-side-encryption-aws-kms-key-id, x-amz-server-side-encryption-context, and x-amz-server-side-encryption-bucket-key-enabled) from the CreateSession request. You don't need to explicitly specify these encryption settings values in Zonal endpoint API calls, and Amazon S3 will use the encryption settings values from the CreateSession request to protect new objects in the directory bucket.

For CopyObject, to encrypt new object copies in a directory bucket with SSE-KMS, you must specify SSE-KMS as the directory bucket's default encryption configuration with a KMS key (specifically, a customer managed key). Then, when you specify server-side encryption settings for new object copies with SSE-KMS, you must make sure the encryption key is the same customer managed key that you specified for the directory bucket's default encryption configuration. For UploadPartCopy, to encrypt new object part copies in a directory bucket with SSE-KMS, you must specify SSE-KMS as the directory bucket's default encryption configuration with a KMS key (specifically, a customer managed key). You can't specify server-side encryption settings for new object part copies with SSE-KMS in the UploadPartCopy request headers. Also, the encryption settings that you provide in the CreateMultipartUpload request must match the default encryption configuration of the destination bucket.

S3 Bucket Keys are always enabled for GET and PUT operations in a directory bucket and can’t be disabled. S3 Bucket Keys aren't supported, when you copy SSE-KMS encrypted objects from general purpose buckets to directory buckets, from directory buckets to general purpose buckets, or between directory buckets, through CopyObject, UploadPartCopy, the Copy operation in Batch Operations, or the import jobs. In this case, Amazon S3 makes a call to AWS KMS every time a copy request is made for a KMS-encrypted object.

When you specify an AWS KMS customer managed key for encryption in your directory bucket, only use the key ID or key ARN. The key alias format of the KMS key isn't supported.