OurPhrase

OurPhrase is a free, open-source iOS application that gives people a pair of shared secret words that change every five minutes—a human-friendly check against impersonation, deepfakes and cloned voices over any communication channel.

No servers, no accounts, no analytics, no network calls. Everything — cryptography, dictionaries, QR generation — is bundled and runs locally.

The fully native SwiftUI app lives in ios/. The original offline PWA remains for legacy users, encrypted-backup migration and protocol compatibility.

OurPhrase is a supplementary check, not proof of identity. Read the disclaimer and threat model before relying on it in high-risk situations.

Development status and the ordered path to the first iOS release are tracked in the project roadmap.

How it works

• Pairing (remote, two channels): User A creates a contact and sends an invitation link (carries a random 160-bit secret + salt + nonce, but not the PIN). A then tells B a 4-digit PIN out loud (call / in person). B opens the link, types the PIN, and both derive the same master key with HMAC-SHA256. A 1-byte checksum catches mistyped PINs at pairing time.

• Pairing (in person): one QR code containing the full secret (PIN included) — scan with the iOS camera and you're done.

• Private names: a profile says who you are when connecting, while each person chooses their own local alias afterwards. The inviter's profile name is never copied into the other person's contact list.

• Verification: both devices compute HMAC-SHA256(masterKey, timeWindow) → two words from the contact's dictionary (Spanish or English, chosen per contact). Words rotate every 5 minutes (RFC-6238-style time windows). During the first minute the previous window's words are shown as a hint, tolerating device clock skew.

• Backup ("cold wallet"): contacts can be exported as an AES-GCM-encrypted file keyed by a 20-word phrase (PBKDF2-SHA256, 310k iterations; words come from the app's own dictionaries — ~181 bits of entropy). The user keeps the file anywhere (iCloud, email, USB) and the words on paper. Restore = file + words on any device; word entry is case/accent/ñ-insensitive. The phrase stays constant across re-exports; the app hints when the backup is stale. Still zero servers. Note: shared keys cannot be regenerated from a personal seed alone (they were agreed with a peer), hence file + words.

Stack

Pure ES2022 + Web Crypto (crypto.subtle). No runtime dependencies except a vendored copy of jsQR (Apache-2.0, minified at js/vendor/jsQR.js) that is lazy-loaded only for the in-app QR scanner. Self-contained QR encoder (byte mode, ECC M, versions 1–16). Service worker precaches everything for full offline / airplane-mode use. iOS standalone install supported (apple-touch-icon, safe-area insets, ui-rounded type).

Files

index.html            single-page UI (5 screens)
css/style.css         iOS-native look, light/dark, safe areas
js/app.js             controller (i18n ES/EN auto-detected)
js/crypto-engine.js   pairing + TOTP→words (isomorphic, tested in Node)
js/dict-es.js|en.js   curated dictionaries (536 ES / 459 EN concrete nouns)
js/qr.js              QR encoder (verified against jsQR + qrcode reference)
sw.js manifest.json   PWA/offline packaging
scripts/make-icons.mjs regenerates icons/ (hand-rolled PNG writer)
tests/                node --test suite (crypto, dictionaries, QR)
ios/                  native SwiftUI iOS/iPadOS application and tests
website/              public site, privacy policy and Universal Link fallback

Develop / test

npm test                       # 20 tests: crypto determinism, dictionary
                               # phonetic-distinctness gate, QR round-trips
python3 -m http.server 8642    # serve locally (SW needs http://localhost or https)

Deploy by copying the folder to any static host over HTTPS (Web Crypto and service workers require a secure context). Then on iPhone: Share → Add to Home Screen.

Security notes

• The PIN travels out-of-band by design; the link alone is not enough to pair.
• The 1-byte PIN checksum trades a small amount of link-interception resistance (10⁴ → ~39 candidate PINs offline) for catching typos — the words themselves would reveal the PIN to a link interceptor after one observed exchange anyway. Treat the invitation link with the same care as a house key.
• Keys live in localStorage, scoped to the app's origin. Deleting the contact (or the site data) destroys them.

Please report vulnerabilities privately as described in SECURITY.md. Do not publish real invitation payloads, keys or recovery phrases.

Contributing and governance

Contributions are welcome. Start with CONTRIBUTING.md, follow the Code of Conduct, and review the governance model.

License and marks

Source code is available under the Mozilla Public License 2.0. Distributed modifications to covered files must remain available under MPL-2.0. The OurPhrase name, logo and visual identity are not granted by the source license; see TRADEMARKS.md. Third-party notices are in NOTICE.