A client computing system inserts selected advertising into digital content. Ads may be inserted into content based on a dynamic advertising matching process that is securely implemented within a hardware-based root of trust. User profiles used in ad matching may be privacy protected and maintained with confidentiality protection in the client computing system and/or a service provider server, respectively. When a client computing system makes a request to the service provider server for content with specified ad slots, the request may be made with the client's EPID signature, which is inherently privacy protected. The hardware-based root of trust protects insertion of selected ads into the linear rendering flow of the content.