Today, we are launching Amazon S3 dual-layer server-side encryption with keys stored in AWS Key Management Service (DSSE-KMS), a new encryption option in Amazon S3 that applies two layers of encryption to objects when they are uploaded to an Amazon Simple Storage Service (Amazon S3) bucket. DSSE-KMS is designed to meet National Security Agency CNSSP 15 for FIPS compliance and Data-at-Rest Capability Package (DAR CP) Version 5.0 guidance for two layers of CNSA encryption. Using DSSE-KMS, you can fulfill regulatory requirements to apply multiple layers of encryption to your data.

Amazon S3 is the only cloud object storage service where customers can apply two layers of encryption at the object level and control the data keys used for both layers. DSSE-KMS makes it easier for highly regulated customers to fulfill rigorous security standards, such as US Department of Defense (DoD) customers.

With DSSE-KMS, you can specify dual-layer server-side encryption (DSSE) in the PUT or COPY request for an object or configure your S3 bucket to apply DSSE to all new objects by default. You can also enforce DSSE-KMS using IAM and bucket policies. Each layer of encryption uses a separate cryptographic implementation library with individual data encryption keys. DSSE-KMS helps protect sensitive data against the low probability of a vulnerability in a single layer of cryptographic implementation.

DSSE-KMS simplifies the process of applying two layers of encryption to your data, without having to invest in infrastructure required for client-side encryption. Each layer of encryption uses a different implementation of the 256-bit Advanced Encryption Standard with Galois Counter Mode (AES-GCM) algorithm. DSSE-KMS uses the AWS Key Management Service (AWS KMS) to generate data keys, allowing you to control your customer managed keys by setting permissions per key and specifying key rotation schedules. With DSSE-KMS, you can now query and analyze your dual-encrypted data with AWS services such as Amazon Athena, Amazon SageMaker, and more.

With this launch, Amazon S3 now offers four options for server-side encryption:

Server-side encryption with Amazon S3 managed keys (SSE-S3)
Server-side encryption with AWS KMS (SSE-KMS)
Server-side encryption with customer-provided encryption keys (SSE-C)
Dual-layer server-side encryption with keys stored in KMS (DSSE-KMS)

Let’s see how DSSE-KMS works in practice.

Create an S3 Bucket and Turn on DSSE-KMS
To create a new bucket in the Amazon S3 console, I choose Buckets in the navigation pane. I choose Create bucket, and I select a unique and meaningful name for the bucket. Under Default encryption section, I choose DSSE-KMS as the encryption option. From the available AWS KMS keys, I select a key for my requirements. Finally, I choose Create bucket to complete the creation of the S3 bucket, encrypted by DSSE-KMS encryption settings.

Upload an Object to the DSSE-SSE enabled S3 Bucket
In the Buckets list, I choose the name of the bucket that I want to upload an object to. On the Objects tab for the bucket, I choose Upload. Under Files and folders, I choose Add files. I then choose a file to upload, and then choose Open. Under Server-side encryption, I choose Do not specify an encryption key. I then choose Upload.

Once the object is uploaded to the S3 bucket, I notice that the uploaded object inherits the Server-side encryption settings from the bucket.

Download a DSSE-KMS Encrypted Object from an S3 Bucket
I select the object that I previously uploaded and choose Download or choose Download as from the Object actions menu. Once the object is downloaded, I open it locally, and the object is decrypted automatically, requiring no change to client applications.

Now Available
Amazon S3 dual-layer server-side encryption with keys stored in AWS KMS (DSSE-KMS) is available today in all AWS Regions. You can get started with DSSE-KMS via the AWS CLI or AWS Management Console. To learn more about all available encryption options on Amazon S3, visit the Amazon S3 User Guide. For pricing information on DSSE-KMS, visit the Amazon S3 pricing page (Storage tab) and the AWS KMS pricing page.

— Irshad