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Client-Side Encryption with KMS Managed Keys (CSE-KMS)

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We have all seen in the media numerous occurrences whereby large international organizations have had their data exposed and leaked that had been stored on S3.  Any sensitive data stored in the cloud MUST be encrypted, and when storing your data on S3 there are multiple different options that you can choose from to enable you to protect your data with encryption.  To help you understand these mechanisms, this course will guide you through the process of how each of them works, not just from an encryption perspective but also at a decryption level.  This will allow you to make the right choice when it comes to selecting the most appropriate method of encryption to align with your own internal security strategy.

Applying encryption is a simple task and it can protect you and your customers from data exposure should a malicious user gain access to your S3 buckets.

If you have thoughts or suggestions for this course, please contact Cloud Academy at support@cloudacademy.com.

Learning Objectives

By the end of this course series you will be able to explain the encryption and decryption process for:

  • Server-Side Encryption with S3 Managed Keys (SSE-S3)
  • Server-Side Encryption with KMS Managed Keys (SSE-KMS)
  • Server-Side Encryption with Customer Provided Keys (SSE-C)
  • Client-Side Encryption with KMS Managed Keys (CSE-KMS)
  • Client-Side Encryption with Customer Provided Keys (CSE-C)

Intended Audience

This course is intended for those who have the responsibility of storing, managing, and protecting data that is stored on Amazon S3. 


This is an advanced level course and so it is essential that you have an understanding of S3 and that you have the knowledge to enable you to upload and retrieve data along with how to select different encryption options. In addition to this, you must also be familiar with the KMS service and understand both CMKs and Data encryption keys. 




Client-Side Encryption with KMS Managed Keys, CSE-KMS. The encryption process is as follows. Using an AWS SDK, such as the Java client, a request is made to KMS for Data Keys that are generated from a specific CMK. This CMK is defined by providing the CMK-ID in the request. KMS will then generate two Data Keys from the specified CMK. One key will be a Plaintext Data Key. The second will be a Cipher blob of the same Data Key. Both keys are then sent back to the client. The client will then combine the Object Data with the Plaintext Data Key to create an encrypted version of the Object Data. The client then uploads both the encrypted Object Data and the Cipher blob version of the Data Key to S3. S3 will then store the encrypted Object Data and associate the Cipher blob Data Key as Metadata of the encrypted Object Data. The decryption process is as follows. A request is made by the client to S3 to retrieve the Object Data. S3 sends both the encrypted Object Data and the Cipher blob back to the client. Using an AWS SDK, such as the Java client, the Cipher blob Data Key is sent to KMS. KMS combines the Cipher blob Data Key with the corresponding CMK to produce the Plaintext Data Key. This Plaintext Data Key is then sent back to the client and the Plaintext Data Key is then used to decrypt the encrypted Object Data.

About the Author
Learning Paths

Stuart has been working within the IT industry for two decades covering a huge range of topic areas and technologies, from data center and network infrastructure design, to cloud architecture and implementation.

To date, Stuart has created 150+ courses relating to Cloud reaching over 180,000 students, mostly within the AWS category and with a heavy focus on security and compliance.

Stuart is a member of the AWS Community Builders Program for his contributions towards AWS.

He is AWS certified and accredited in addition to being a published author covering topics across the AWS landscape.

In January 2016 Stuart was awarded ‘Expert of the Year Award 2015’ from Experts Exchange for his knowledge share within cloud services to the community.

Stuart enjoys writing about cloud technologies and you will find many of his articles within our blog pages.