A financial services company stores highly sensitive customer records in a public cloud IaaS environment. As part of its data governance program, the security team is mapping controls to each phase of the cloud data lifecycle. They are now focused on the final phase, where information that has reached the end of its retention period must be rendered permanently unrecoverable. Because the underlying storage hardware is owned and multi-tenanted by the cloud provider, physical destruction of the media is not possible for the customer. Which technique is the MOST appropriate for the security team to rely on to securely address this lifecycle phase?