AWS KMS CLI Documentation:

https://awscli.amazonaws.com/v2/documentation/api/latest/reference/kms/index.html

Encrypting Data in KMS:

aws kms encrypt --key-id 1234abcd-12ab-34cd-56ef-1234567890ab --plaintext fileb://plain-text.txt

Decrypting Data in KMS

aws kms decrypt --ciphertext-blob <value>