The goal of the BMFTR-funded “Security for the Medical Internet of Things” (Sec4IoMT) project is to develop economically viable and technically secure solutions for the long-term protection of medical devices. The basis for this is secure communication channels. For this reason, corresponding security architectures and security retrofitting processes—that is, processes in which existing devices are adapted to current security requirements—are being developed, tested by medical device manufacturers for practical suitability, and analyzed for their cost-effectiveness. Research is being conducted on how updates to software, firmware, libraries of cryptographic algorithms, certificates, and keys can be installed and distributed even for large quantities and diverse users without jeopardizing product approval. To this end, the devices are to remain with the user and be online only temporarily.