Palimpsest

Palimpsest is an encrypted diary and notes app with deniable vaults: one password field, any number of vaults, and no way to tell from the file how many there are. Every password opens its own vault. A decoy password shows a believable diary; another shows the real one.

Experimental, not audited. It protects against a curious partner, a thief and a quick border check. It does not protect against a forensic lab, spyware on the phone, or someone who keeps demanding passwords. If an adversary keeps copies of the file from different moments and knows a decoy password, a hidden vault can give itself away. The threat model in the source repository has the details.

Writing

• Notes in a grid with folders, tags, pins and colours; a diary with a timeline and a month calendar; to-dos
• Markdown editor that hides the markers away from the line you edit
• Photos and voice notes captured in memory, never in the gallery; photos cropped before they are stored, EXIF and location dropped
• Links between entries, backlinks and a graph of links where you link entries by dragging one onto another
• Search, search inside an entry, trash with 30-day expiry

Vaults

• Create, change the password, delete a vault (its blocks are overwritten in place)
• A one-shot rule: on the next opening of this vault, destroy the vault with password X
• Backup of everything, restore, export of one vault under its own password, import with merging

Privacy

• No internet permission, no trackers, no ads
• Screenshots blocked unless you allow them; no preview in recent apps
• Incognito keyboard, no autofill, copied text cleared after 60 seconds
• Locks on screen off, after idle time and in the background

The core is written in Rust: Argon2id, XChaCha20-Poly1305 and BLAKE2b; the container is a pile of 4096-byte blocks that all look like random bytes, with random chaff added all the time.

Two unused permissions that a library added (network state, foreground service) are removed.