strypt

Status: Phase 1 done (2026-08-22) — no audit, no release, no hardening phase yet

PDF, JPEG, PNG, and WebP are implemented. Everything else is recognised and reported as unsupported; it is not processed. All seven Phase 1 exit criteria are met: the handlers were swept over 102 files from real producers — real camera maker notes included — the mat2 differential covers all four formats, performance is measured, CI is green on Linux, macOS and Windows, and 80 CPU-hours of fuzzing across five targets found four real PDF defects, each fixed with a regression test, ending in a 12-hour PDF run with no crashes, hangs or OOMs.

What "Phase 1 done" does not mean. There has been no external audit and no release. No tool can guarantee total metadata removal and strypt does not claim to. Hardening is Phase 3 and has not started, so the 100-CPU-hour-per-handler fuzzing budget is not met — PDF was still finding new code paths at hour 12. Two limitations are documented rather than fixed: the JPEG APP14 marker mat2 removes, and a PDF with 19-byte cross-reference entries that strypt refuses and mat2 handles. Performance is one machine; Linux and Windows are unmeasured.

Phase	Status
0 — Foundation: docs, workspace, CI gates	✅ Done
1 — Core engine + CLI (JPEG, PNG, WebP, PDF)	✅ Done 2026-08-22 — all seven exit criteria met; see the caveats above
2 — Expanded formats · 3 — Hardening · 4 — Distribution	⬜ Not started
5 — GUI · 6 — File-manager integration · 7 — Community	⬜ Not started

Full phase definitions and exit criteria: docs/ROADMAP.md.

For anything other than PDF, JPEG, PNG, and WebP, and for anything that matters, use mat2 or ExifTool — both mature, actively maintained, and covering far more formats. docs/PRD.md §4 explains where strypt intends to differ.

Development is AI-assisted under defined constraints — see Development process.

Remove hidden metadata from files before you share them.

Photos carry GPS coordinates and camera serial numbers. PDFs carry author names, organisation names, and editing timestamps. None of it is visible in a normal viewer, and all of it survives to publication. strypt finds it and strips it out.

A single self-contained binary. Memory-safe Rust. No network access in any code path.

Trying it

cargo run -p strypt-cli -- show corpus/pdf/info-dictionary.pdf
cargo run -p strypt-cli -- show corpus/jpeg/exif-gps.jpg
cargo run -p strypt-cli -- strip corpus/jpeg/exif-gps.jpg

show never writes. strip writes a copy beside the input and leaves the original alone unless you ask for --in-place. Full command reference and exit codes: INSTRUCTIONS.md.

Scope (Phase 1)

More formats — Office documents, audio, video — are Phase 2. See docs/ROADMAP.md.

Planned usage

strypt show photo.jpg              # report what metadata is present; changes nothing
strypt strip photo.jpg             # write a sanitised copy
strypt strip --in-place *.pdf      # overwrite originals (opt-in, never the default)
strypt show --json ./docs          # machine-readable output for scripting

Design commitments

• No network access, ever. No update checks, no telemetry, no crash reporting. Enforced by a CI gate, not by a promise.
• Your image data is not re-encoded. Removing metadata is a container operation. Stripped photos stay pixel-identical.
• Safe by default. Copy-out rather than in-place. Loud failures rather than silent ones.
• No unsafe code, and no panics on malformed input.
• Honest about limits. See below.

What strypt will not do

This matters as much as the feature list.

• It does not redact. A PDF with a black box drawn over text still contains that text.
• It does not change what your document says, or anonymise your writing style.
• It does not clean filenames, and budget_final_jsmith_home.pdf identifies you regardless.
• It does not protect against metadata a platform adds after you upload.
• It cannot defeat fingerprinting — encoder quirks and camera sensor noise can identify a device from pixel data alone, with no metadata present at all.
• No tool can guarantee complete metadata removal from complex formats. strypt will never claim otherwise.

Read docs/THREAT_MODEL.md before relying on this tool for anything that matters.

Installation

cargo install strypt-cli    # requires a Rust toolchain

That is the only install path, and 0.0.1 is not a release. The crate was published early to hold the name, not because the project is ready to be depended on — Phase 3 hardening has not started and there has been no external audit. Prebuilt binaries, checksums, signing, reproducible builds, and a Homebrew formula are Phase 4 and do not exist yet. See docs/ROADMAP.md.

Documentation

Prior art

strypt owes its problem framing to mat2 by Julien Voisin, built with support from the Tails project, and uses ExifTool as a verification reference. Both are excellent and actively maintained; strypt is a differently-engineered option, not a replacement for either.

License

Dual-licensed under MIT or Apache-2.0, at your option.

Contributions are accepted under the same dual licence, per the Apache-2.0 contribution clause, unless you state otherwise.