Methods and apparatus for ultra-secure accelerators. New ISA enqueue (ENQ) instructions with a wrapping key (WK) are provided to facilitate secure access to on-chip and off-chip accelerators in computer platforms and systems. The ISA ENQ with WK instructions include a dest operand having an address of an accelerator portal and a scr operand having the address of a request descriptor in system memory defining a job to be performed by an accelerator and including a wrapped key. Execution of the instruction writes a record including the src and a WK to the portal, and the record is enqueued in an accelerator queue if a slot is available. The accelerator reads the enqueued request descriptor and uses the WK to unwrap the wrapped key, which is then used to decrypt encrypted data read from one or more buffers in memory. The accelerator then performs one or more functions on the decrypted data as defined by the job and writes the output of the processing back to memory with optional encryption.