SPIFFE focuses on who a workload is. It issues cryptographic identities to services and workloads so they can prove their authenticity to each other without relying on stored secrets. OAuth focuses on what a workload is allowed to do. It defines how access is delegated and controlled when one service needs to interact with another or call an external API.
As agents scale and operate continuously, MCP servers are becoming long-lived access intermediaries, concentrating privilege in ways security teams have already struggled to contain.
