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nvs: scrub — erase dead values from the flash itself - #6
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… itself. NVS rewrites and removes by marking the old entry erased; the old bytes stay until the page is erased, so a sealed passphrase's plaintext was still readable off an encrypted C6's flash (2026-10-15). scrub compacts each page holding an erased entry; every live value survives it Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Ttimmahlax
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rusty_esp_core 0.1.3 adds Nvs::scrub: replaced and removed values are erased from the flash itself, not just marked erased (#6). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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NVS rewrites and removes a value by marking its old entry erased in the page bitmap; the old bytes stay on the flash until that page is erased, which only a full partition's compaction does. For a secret that was rewritten (a passphrase sealed where it lay, a key rotated) that leaves the old value readable off a dumped flash.
Found on an ESP32-C6 with flash encryption on (2026-10-15): the extender's settings were sealed in place (
rusty_esp_midseal), yet the network name and passphrase were still in the clear in a raw read of the nvs partition.Nvs::scrubcompacts every page that holds an erased entry (reusingcompact, one active page kept), so each is erased once its live entries are copied out. Tests: the hazard shown and removed, live values read back after a fresh open, a reserve page kept, writes still taken; a clean partition is left byte for byte. On the C6:scrubbed 1 pagesat boot, and a raw read of the partition afterwards shows neither the name nor the passphrase.🤖 Generated with Claude Code