If you don't want to do mutual authentication then may not need to do anything special. In theory, your servers can get a regular certificate from a public CA.

If you don't want to do mutual authentication then may not need to do anything special. In theory, your servers can get a regular certificate from a public CA. You would get better security with a private CA, ensuring that your devices submit data only to you and not to an impersonator. Without mutual authentication you won't be able to authenticate the devices themselves. Perhaps you intend to have a different mechanism, perhaps sign the messages? I feel that signing the messages would provide better security guarantees as the signatures will accompany the data. I think the most important aspect to get right is to have the ability to update the root material. No matter what CAs you end up using, their roots will eventually expire and will need to be replaced. Clearly, you don't want to lose the root material as that would be catastrophic. Using two separately managed roots would probably be a good idea. AWS and Google have private CA services, and EJBCA is also worth exploring, for example: https://doc.primekey.com/ejbca/solution-areas/iot-and-device-identities https://doc.primekey.com/ejbca/solution-areas/iot-and-device...