In an embodiment, a peripheral interface controller may include an inline cryptographic engine which may encrypt data being sent over a peripheral interface and decrypt data received from the peripheral interface. The encryption may be transparent to the device connected to the peripheral interface that is receiving/supplying the data. In an embodiment, the peripheral interface controller is included in a system on a chip (SOC) that also includes a memory controller configured to couple to a memory. The memory may be mounted on the SOC in a chip-on-chip or package-on-package configuration. The unencrypted data may be stored in the memory for use by other parts of the SOC (e.g. processors, on-chip peripherals, etc.). The keys used for the encryption/decryption of data may remain within the SOC.