Server-Side Encryption with KMS managed keys, SSE-KMS. The encryption process is as follows. Firstly, a client uploads object data to S3. S3 then requests data keys from a KMS-CMK. Using the specified CMK, KMS generates two data keys, a plain text data key and an encrypted version of the same data key. These two keys are then sent back to S3. S3 then combines the object data and the plain text data key to perform the encryption. This creates an encrypted version of the object data which is then stored on S3 along with the encrypted data key. The plain text data key is then removed from memory. The decryption process is as follows. A request is made by the client to S3 to retrieve the object data. S3 sends the associated encrypted data key of the object data to KMS. KMS then uses the correct CMK with the encrypted data key to decrypt it and create a plain text data key. This plain text data key is then sent back to S3. The plain text data key is then combined with the encrypted object data to decrypt it. This decrypted object data is then sent back to the client.