Product Requirements: Secure Communication App¶
1. Product Vision¶
To provide a simple, reliable, and exceptionally secure communication tool where users can make private video and audio calls, confident that their conversations are protected from all forms of eavesdropping.
2. Core User Features¶
The app will deliver a focused set of features to ensure a high-quality, secure calling experience.
| Feature | Description |
|---|---|
| Secure 1-to-1 Calls | Users can make crystal-clear, private video and audio calls to another user. |
| Secure Group Calls | Users can create and participate in group video and audio calls with the same level of security as 1-to-1 calls. |
| Call History | Users can view a history of their past calls (incoming, outgoing, missed). |
| Rejoin Active Calls | If a user is disconnected from an ongoing call, they can easily rejoin it from their call history. |
| Contact Management | Users can manage a list of contacts within the app for quick and easy calling. |
| Simple Authentication | Users can sign up and log in easily using their email, phone number, or existing Apple/Google accounts. |
3. Security & Privacy: The Core Promise¶
The fundamental principle of this app is that user conversations are private and cannot be accessed by anyone else, not even by us (the company). This is achieved through a state-of-the-art security model called End-to-End Encryption (E2EE).
How It Works (In Simple Terms)¶
- Your Device Holds the Key: When you sign up, your device creates a unique digital "key" that is stored securely on the device itself. This key never leaves your phone.
- Locked Conversations: Every call (video, audio) is "locked" using these keys. Only the devices of the people in the call have the keys to "unlock" and listen to the conversation.
- No Middleman Access: The call data travels through our servers, but it remains locked. Our servers cannot unlock the data, so they cannot listen to the calls. This makes the communication "unhackable" from the outside.
- Constantly Changing Locks: For group calls, the digital "lock" is automatically changed every 5 minutes. This means that even in the extremely unlikely event a key is compromised, it would only expose a tiny fraction of the conversation, ensuring long-term security (a feature called "Forward Secrecy").
Security Guarantees¶
- Absolute Privacy: Only the intended participants can see or hear the call.
- No Server Eavesdropping: The company and its infrastructure cannot access call content.
- Hardware-Level Protection: On iPhones, the user's primary digital key is protected by the device's Secure Enclave, a specialized hardware security component.
- Resilience: The system is designed to recover from temporary decryption errors by automatically resynchronizing keys between participants, ensuring call stability without compromising security.