Cryptosend privacy-first file sharing (in progress)
I’m building Cryptosend, a mobile app that makes it simple to lock any file with strong, modern encryption and share it on your terms without exposing sensitive data to servers. All protection happens on the device; recipients unlock only with the right secret.
The problem
Sharing personal or work files over email, chat, or cloud links often leaves traces and control behind. Once a file is out, it’s out. I’m exploring a safer default: private by design, where access requires explicit permission and expires automatically.
The solution (high level)
- On-device protection: Files are encrypted and decrypted locally; plaintext never touches the server.
- Controlled access: Senders can set time-bound access, limit incorrect unlock attempts, and require re-authentication each time a file is opened.
- Flexible sharing: Share the unlock secret in a way that fits the moment manually, by QR, or using a public/private key flow for power users.
- Ephemeral delivery (optional): If you use a link, it’s temporary and stores only the encrypted blob with minimal metadata before auto-deleting. No secrets are ever stored.
This overview intentionally omits implementation details to protect the IP while conveying the value and design principles.
What makes it different
- Zero-knowledge posture: Cryptosend can’t read your content or your secrets by design.
- Defensive UX: Built-in safeguards like attempt limits, automatic expiry, and optional self-destruct after viewing (Pro) make casual leaks far less likely.
- Secure-by-default viewing: Decrypted content lives in memory, is sandboxed, and is cleared when you navigate away, lock the screen, or close the app. Sensitive screens block screenshots.
Experience at a glance
A clean, minimal flow Select → Protect → Share with tabs for Encrypt, Decrypt, History, and Settings. Biometric unlock and dark/light themes keep it modern and familiar, while security stays front-and-centre.
Audience & platforms
Designed for individuals and teams who send sensitive documents, creative work, or personal media and want peace of mind. Targeting iOS & Android with a single codebase for consistency and speed.
Current status
Actively in development. Scope includes core protection flows, secure sharing options, and a lightweight backend for temporary delivery when needed. A Pro tier will layer in advanced controls and extended logs.
My role
End-to-end owner across product direction, UX, and technical leadership, defining the threat model, shaping the user journey, and orchestrating a pragmatic build that balances security with everyday usability.
Success measures
- Users can protect and share a file in under 30 seconds, without jargon.
- No plaintext secrets or content are persisted outside the device.
- Access controls (expiry, attempts, re-auth) work predictably and are easy to audit in History.
What’s next
Private testing, polish on the protection flow, and iterative hardening of edge cases (offline use, large files, and recovery paths). If you’d like to follow along or test early builds, reach out.
Note: This page intentionally stays high-level and avoids implementation specifics (algorithms, libraries, and backend details) to protect the concept while it’s in progress.
