Do not open a public GitHub issue for security vulnerabilities.

Use GitHub Private Vulnerability Reporting to submit a report privately. We will acknowledge the report within 7 days and keep you informed as we work on a fix.

Mesh-Talk is a peer-to-peer LAN chat client that runs on each user's own machine; there is no central server. Key security properties:

• No central trust — peers are discovered over signed UDP multicast and connect directly over a Noise-encrypted TCP channel on the local network.
• End-to-end encryption + forward secrecy — DMs use a Double Ratchet, group channels a sender-key ratchet; transport is Noise (snow) with the peer's device identity bound into the handshake. Relays only ever see ciphertext.
• Encryption at rest — per-device/account keystores and the message stores are encrypted with a key derived from the user's password (PBKDF2-600k + AES-256-GCM); they are unlocked only after login.
• Local data only — all user data lives under ~/.mesh-talk/ (Windows: %USERPROFILE%\.mesh-talk); nothing is uploaded.

This is an experimental project. The following are tracked, not yet hardened:

• Contact requests/responses are signed with the sender's ed25519 key and verified on receipt (a present-but-invalid signature is rejected). However, the binding between a user_id and its public key is trust-on-first-use — there is no key directory, so a first contact from an unknown key is accepted.
• LAN transport is unauthenticated at the network layer; trust the network you run on.

Please mention any of these in a report only if you have a concrete exploit beyond the documented limitation.

Every push runs, and these are visible as README badges / the repo Security tab:

• SAST: CodeQL (code scanning) + cargo clippy -D warnings.
• Secrets: gitleaks (history + diff).
• Dependencies: cargo-deny (advisories/licenses/bans/sources), cargo-audit (RUSTSEC), cargo-machete (unused), Dependabot, and a PR Dependency Review gate.
• Fuzzing: cargo-fuzz targets over every untrusted wire decoder (weekly + on demand), with an always-on decoder_smoke test as the fast gate.
• Mutation testing: cargo-mutants (weekly + on PR diff) to catch weak tests.
• Coverage: cargo-llvm-cov → Codecov.
• Posture score: OpenSSF Scorecard (weekly), published to the badge above.

Every release artifact is a per-platform .zip published with three independent proofs. Download the .zip, its .zip.bundle (Sigstore signature), and — for a tagged release — the SBOM, then verify:

1. Checksum — each zip contains a SHA256SUMS; after unzipping:

   sha256sum -c SHA256SUMS        # macOS: shasum -a 256 -c SHA256SUMS

2. Sigstore signature (proves the zip came from this repo's release workflow, keyless):

   cosign verify-blob \
     --bundle "mesh-talk_<ver>_<os>_<arch>.zip.bundle" \
     --certificate-oidc-issuer https://token.actions.githubusercontent.com \
     --certificate-identity-regexp '^https://github.com/OctopusGarage/mesh-talk/.github/workflows/release.yml@.*$' \
     "mesh-talk_<ver>_<os>_<arch>.zip"

3. SLSA build provenance (GitHub-native attestation of where/how it was built):

   gh attestation verify "mesh-talk_<ver>_<os>_<arch>.zip" --repo OctopusGarage/mesh-talk

4. SBOM — a CycloneDX mesh-talk.cdx.json (full dependency inventory) is attached to each tagged release for auditing the supply chain.

A failed checksum or signature means the download was tampered with or did not come from this project — do not run it.