A cryptographically scrubbable disk performs erasure of a cryptographic key covering a body of data to render the body of data unintelligible. A scrub controller interfaced between a computing appliance and a storage volume generates a scrub key and encrypts each block of data written to the storage volume using the scrub key. Data read commands decrypt using the same key. The scrub controller is an electronically separate conduit having independent memory and power, thus the scrub key remains within the scrub controller and unexposed, and is thus inaccessible via the processor of the computing appliance. The scrub key remains in the scrub controller such that the scrub key never leaves the scrub controller and is also inaccessible to retrieval since the scrub controller does not share memory or access with the computer and is thus electronically separate from the supported computing appliance.