https://awscli.amazonaws.com/v2/documentation/api/latest/reference/kms/import-key-material.html

aws kms import-key-material \

--key-id 1234abcd-12ab-34cd-56ef-1234567890ab \

--encrypted-key-material fileb://EncryptedKeyMaterial.bin \

--import-token fileb://ImportToken.bin \

--expiration-model KEY_MATERIAL_EXPIRES \

--valid-to 2021-09-21T19:00:00Z

The correct answer is A. A customer managed CMK that uses customer provided key material.

A customer managed CMK is a KMS key that you create, own, and manage in your AWS account. You have full control over the key configuration, permissions, rotation, and deletion.You can use a customer managed CMK to encrypt and decrypt data in AWS services that are integrated with AWS KMS, such as Amazon EBS1.

A customer managed CMK can use either AWS provided key material or customer provided key material. AWS provided key material is generated by AWS KMS and never leaves the service unencrypted. Customer provided key material is generated outside of AWS KMS and imported into a customer managed CMK.You can specify an expiration date for the imported key material, after which the CMK becomes unusable until you reimport new key material2.

To meet the criteria of automatically expiring the key material in 90 days, you need to use customer provided key material and set the expiration date accordingly. This way, you can ensure that the data encrypted with the CMK will not be accessible after 90 days unless you reimport new key material and re-encrypt the data.

The other options are incorrect for the following reasons:

B. A customer managed CMK that uses AWS provided key material does not expire automatically. You can enable automatic rotation of the key material every year, but this does not prevent access to the data encrypted with the previous key material.You would need to manually delete the CMK and its backing key material to make the data inaccessible3.

C. An AWS managed CMK is a KMS key that is created, owned, and managed by an AWS service on your behalf. You have limited control over the key configuration, permissions, rotation, and deletion. You cannot use an AWS managed CMK to encrypt data in other AWS services or applications.You also cannot set an expiration date for the key material of an AWS managed CMK4.

D. Operation system-native encryption that uses GnuPG is not a solution that uses AWS KMS. GnuPG is a command line tool that implements the OpenPGP standard for encrypting and signing data. It does not integrate with Amazon EBS or other AWS services.It also does not provide a way toautomatically expire the key material used for encryption5.