The verifier constructs a computational problem, which cannot be solved (in reasonable time or at all) using less than the specified amount of memory, and sends it to the device.
Security of this approach is obvious, but it includes transfer of a huge amount of data (twice the size of the device's memory).
[2][verification needed][3]: 16 Avoiding the huge data transfer requires a suitable (as stated in Overview) computational problem, whose description is short.
Dziembowski et al.[1][verification needed] achieve this by constructing what they call an (m − δ, ε)-uncomputable hash function, which can be computed in quadratic time using memory of size m, but with memory of size m − δ it can be computed with at most a negligible probability ε.
Proof of secure erasure on the other hand requires the prover to be unable to convince the verifier using less than the specified amount of memory.