Defeating PCIe DMA & External Kernel Cheats through Usermode

Anti-cheat systems have spent a decade climbing into the kernel to detect external tools, yet cheats such as PCIe DMA devices run entirely outside the host CPU and read game state as plaintext. We argue the problem is not a lack of privilege but a lack of data secrecy. This paper presents a user-mode design that adapts Pointer Authentication Codes to x64 in software. Critical pointers are protected by a master key split across vector registers, a process-bound identity share, and a self-migrating heap share, so physical-memory readers recover only address-tethered ciphertext. Control-flow integrity checks, dual-pool shadow code verification, server-authoritative key rotation, and silent cryptographic poisoning raise the cost of internal and emulated attacks. On a test game, the hot path measures 300 to 500 cycles (median about 400), with early tuning pointing to about 140, and the cold path roughly 20,000 cycles (rounded median). The goal is not to make cheating impossible but to make it difficult and annoying enough to be impractical, and internal cheats can still bypass the current implementation with enough effort.