For the actual transport layer, I’d strongly avoid shared memory unless you fully control both processes and can isolate the mapping to a single-writer/single-reader model with page-level permission checks—most IPC vulnerabilities I’ve seen come from sloppy memory-mapped regions that either process can blindly trust. Named pipes with message framing (length-prefixed, not null-terminated) are the more defensible default because you get discrete messages and can enforce ACLs on the pipe SID. The critical piece nobody emphasizes enough is mutual authentication: the anti-cheat service shouldn’t just assume the game client is legit, and the client shouldn’t trust arbitrary callers writing to its pipe. Bind both endpoints to a well-known security descriptor and verify the remote process’s image signature + session ID on every message boundary. If you’re on Windows, wrap the pipe handle with a per-message integrity level check and reject anything below SYSTEM/High.
On the architecture side, keep the anti-cheat service in its own session (Session 0 isolation on modern Windows) so the game client can’t attach a debugger or inject into it, and never let the game process call back into privileged code directly—route everything through a small, signed gateway that marshals requests. Encrypt the payload even on the local loopback using an ephemeral key exchanged via the service’s signed bootstrap token, because memory-scraping tools and ring-0 rootkits can still read your process memory regardless of pipe ACLs. Finally, treat every IPC message as untrusted input: enforce strict schema validation, cap message sizes, and add monotonic sequence counters to detect replay or reordered calls. I’ve seen anti-che
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