Cryptgeon

Cryptgeon is a secure note and file sharing service inspired by PrivNote. Notes are encrypted in the browser before upload, so the server stores only ciphertext and cannot decrypt the content.

Key Features

• Client-side encryption using AES-GCM; encryption keys are not sent to the server
• Share both text notes and files
• Expiration controls via maximum views and time-based expiry
• In-memory storage with Redis, designed to avoid disk persistence
• Web UI plus a CLI client for creating and sharing secrets
• Health endpoint for basic service monitoring

Use Cases

• Share one-time secrets (passwords, tokens) with a view limit
• Send sensitive notes with an expiration time for temporary access
• Share files securely without the server being able to read them

Limitations and Considerations

• View-count enforcement can be imperfect in multi-instance deployments due to race conditions
• HTTPS is required for browser cryptography features
• In-memory storage means data can be evicted depending on Redis memory policies

Cryptgeon is a practical option for teams and individuals who need simple, temporary secret sharing with strong privacy properties. Its minimal server trust model and expiring links make it well-suited for operational workflows and ad-hoc secure exchanges.