An Information-Theoretical Analysis of the Minimum Cost to Erase Information

TL;DR

This paper analyzes the minimum number of overwrites needed to erase information from storage devices, using information theory to establish bounds under different independence criteria.

Contribution

It introduces a theoretical framework for quantifying the minimal overwrite cost to erase information based on mutual information constraints.

Findings

Derived bounds on minimum overwrite cost under weak and strong independence criteria

Established relationships between mutual information and overwrite efficiency

Provided insights into optimal erasure strategies for secure data deletion

Abstract

We normally hold a lot of confidential information in hard disk drives and solid-state drives. When we want to erase such information to prevent the leakage, we have to overwrite the sequence of information with a sequence of symbols independent of the information. The overwriting is needed only at places where overwritten symbols are different from original symbols. Then, the cost of overwrites such as the number of overwritten symbols to erase information is important. In this paper, we clarify the minimum cost such as the minimum number of overwrites to erase information under weak and strong independence criteria. The former (resp. the latter) criterion represents that the mutual information between the original sequence and the overwritten sequence normalized (resp. not normalized) by the length of the sequences is less than a given desired value.