Dear Tjark
Thank you for Submitting the question. Can you give me some more information about the use case? for example do you want the attribute IBAN to be encrypted and saved in Mendix cloud then probably it will be a good idea to use the mendix encryption module.
Are you using the AWS RDS database then you might want to have a look at the AWS documentation Encrypting Amazon RDS resources - Amazon Relational Database Service
OR do you want Mendix studio Pro to connect to AWS KMS ?