You can create Asymmetric key pairs (Encrypt/Decrypt) in AWS KMS. Current AWS CLI allow for public key to be accessed (https://awscli.amazonaws.com/v2/documentation/api/latest/reference/kms/get-public-key.html)
I am not able to see this being available in Terraform's KMS resource. Am I missing something or this is just not available in latest release yet,
Its not supported in terrorism for now. There are some github issues related to this already, such as here.