{
  "slug": "history-independence",
  "term": "History independence",
  "aliases": [
    "History-independent storage"
  ],
  "definition": "History independence limits what a stored representation reveals about prior operations beyond the abstract state permitted by its security model.",
  "note": "Observation model: Weak history independence considers one inspection; strong history independence considers repeated inspections. The protected representation and permitted observations must be specified. [hiflash]\n\nDifferent guarantees: Hiding a remote access trace does not automatically hide history after client compromise. In vORAM+HIRB, the HIRB structure is history independent but the combined system permits bounded recent-history leakage; its secure-deletion guarantee is separate. The model assumes an honest-but-curious server and locally erasable client memory. [voram-hirb]",
  "status": "research",
  "advantages": [],
  "limitations": [
    {
      "text": "A property proved for one layer does not automatically cover the physical flash layout beneath it.",
      "citationIds": [
        "hiflash"
      ]
    }
  ],
  "related": [
    "oblivious-ram",
    "cryptographic-erase",
    "ftl"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-11-12",
  "citations": [
    {
      "id": "hiflash",
      "title": "Chen and Sion. HiFlash: A History Independent Flash Device. arXiv:1511.05180v1 (2015), sections II, IV and VI.",
      "url": "https://arxiv.org/abs/1511.05180v1",
      "accessed": "2026-11-12"
    },
    {
      "id": "voram-hirb",
      "title": "Roche, Aviv and Choi. A Practical Oblivious Map Data Structure with Secure Deletion and History Independence. arXiv:1505.07391v2, sections 1.2-1.3 and 3.",
      "url": "https://arxiv.org/abs/1505.07391v2",
      "accessed": "2026-11-12"
    },
    {
      "id": "hesela",
      "title": "Hesela: Deleted content and historical traces are different targets",
      "url": "https://hesela.com/analyses/ssd-sanitization-trim-evidence/#history-independence",
      "accessed": "2026-11-12"
    }
  ]
}