The present disclosure includes systems and methods for securing data direct I/O (DDIO) for a secure accelerator interface, in accordance with various embodiments. Historically, DDIO has enabled performance advantages that have outweighed its security risks. DDIO circuitry may be configured to secure DDIO data by using encryption circuitry that is manufactured for use in communications with main memory along the direct memory access (DMA) path. DDIO circuitry may be configured to secure DDIO data by using DDIO encryption circuitry manufactured for use by or manufactured within the DDIO circuitry. Enabling encryption and decryption in the DDIO path by the DDIO circuitry has the potential to close a security gap in modern data central processor units (CPUs).