Norman Hardy's 1988 paper named the "confused deputy problem" — a compiler with two sources of authority tricked into overwriting a billing file

Norman Hardy coined the term "confused deputy" in "The Confused Deputy (or why capabilities might have been invented)," published in ACM SIGOPS Operating Systems Review 22(4), October 1988, pp. 36–38. Hardy hosted his own text of the paper at cap-lore.com.

The example is small and concrete. Hardy's operating system had granted a Fortran compiler a "home files license" so the compiler could write to a statistics file it owned. The compiler also accepted, as a normal argument, the name of a file to receive optional debug output. A user who knew the name of the system's billing file passed that name as the debug-output filename. The compiler dutifully opened it and overwrote it — because the compiler, not the user, held the authority to write there. Nothing was misconfigured; the compiler simply acted on authority from two sources at once and could not tell which request deserved which authority: "The fundamental problem is that the compiler runs with authority stemming from two sources. (That's why the compiler is a confused deputy.)"

The paper's subtitle frames the diagnosis as the motivation for capability-based security: a capability bundles the designation of a resource with the authority to use it, so a program cannot be handed a bare name that silently draws on privileges the caller never had. Hardy's later capability work (the KeyKOS nanokernel; the framing "a capability combines designation with authority") develops the same principle.

The structural point outlasts the 1970s-scale example: any deputy holding its own standing privileges plus caller-supplied input, with no way to bind each action to the authority that should govern it, is exploitable without any misconfiguration. That is why the term travels forward into 2026 AI-agent security.