Which solution meets these requirements?
Use client-side encryption with an AWS KMS customer-managed key implemented with the AWS Encryption SDK.
Use AWS CloudHSM to store the keys and perform cryptographic operations. Save the encrypted text in Amazon S3.
Use an AWS KMS customer-managed key that is backed by a custom key store using AWS CloudHSM.
Use an AWS KMS customer-managed key with the bring your own key (BYOK) feature to import a key stored in AWS CloudHSM.
Explanations:
Client-side encryption requires the application to manage encryption keys, which may not be validated to FIPS 140-2 Level 3, and does not use AWS-managed keys. Additionally, it does not store keys in a hardware security module.
While AWS CloudHSM can be used to store keys and perform cryptographic operations, it does not natively integrate with Amazon S3 for key management. Therefore, it does not meet the requirement of using an AWS service for key management in conjunction with S3.
An AWS KMS customer-managed key backed by a custom key store using AWS CloudHSM meets the requirements. It allows the company to manage keys while ensuring that the keys are protected in a FIPS 140-2 Level 3 validated hardware security module. This solution integrates directly with Amazon S3 and Amazon Athena for seamless encryption and decryption.
The BYOK feature allows customers to import keys into AWS KMS, but it does not explicitly require or ensure that these keys are stored in a FIPS 140-2 Level 3 validated hardware security module. Therefore, it does not fully meet the specified requirements.
It seems to me that the answer is:
Use an AWS KMS customer-managed key that is backed by a custom key store using AWS CloudHSM.