Adding End-to-End Encryption (E2EE) to Stream Chat - What You Need To Know

Overview

End-to-end encryption (E2EE) ensures that only the communicating users can read the contents of their messages. While E2EE enhances privacy, it also introduces challenges for moderation and compliance. This article provides a high-level guide on adding E2EE to our chat service.

Stream Chat includes many industry-standard security considerations, including encrypting payloads while in transit and encrypting data at rest. 

Impact on Moderation and Observability

E2EE prevents anyone other than senders and recipients of messages from reading content, making our suite of moderation tools largely ineffective. You will not benefit from

1. Block Lists: Block a list of words or phrases from being used in messaging
2. Advanced Filters: Block domains and emails and use REGEX filtering
3. AI Tools: Use behavior analysis to identify suspicious patterns.
4. Pre-Send Message Hooks: The pre-send message hook will not have access to message contents because it will be encrypted. 

Basic Integration Concepts

Adding End-to-End Encryption adds a couple of stages to the integration

1. Outgoing messages must be encrypted by overriding the logic in the MessageInput component (or SDK equivalent) 
2. To show a list of the messages, the data must be decrypted on the device and passed to the MessageList components
3. Offline Storage can still be used because messages are decrypted as they are shown on screen

An essential guide on integrating an End-to-End Encryption service with our Flutter SDK can be found here. 

Although integrating E2EE is possible with our UI SDKs, it is not altogether supported as an out of the box feature. It will require some customization and engineering resources on your side, which you should account for. 

Similarly, we do not have a preferred vendor or partner for E2EE, but there are several viable options available today. 

Dashboard Explorer and Debugging Tools

With E2EE, only metadata such as timestamps, user activity logs, and message size will be accessible. This means that our regular explorer features on the dashboard will not be effective at viewing content. 

Regulatory Challenges

End-to-end encryption is not necessary for a HIPAA-compliant Chat application. Most healthcare companies provide services without end-to-end chat, voice, and video encryption.

End-to-end encryption can also raise compliance issues, as certain jurisdictions may require access to user communications for law enforcement purposes. For example, Telegram faced legal scrutiny for its E2EE features.

• Legal Compliance: Be aware of local regulations and consider mechanisms like key escrow, where authorities may need access under certain conditions.
• User Consent: Inform users about E2EE and its implications, especially in regions with strict privacy laws (e.g., GDPR).

Conclusion

E2EE can improve user privacy but requires carefully considering moderation tools and legal obligations. By adopting moderation strategies and ensuring compliance with local regulations, you can integrate E2EE effectively into your chat service.