Learn the concepts¶
Each concept starts with a simple answer, then an example, its limits and sources.
- Encryption in transit
- Protects the connection between two points. The server may be one of those points.
- End-to-end encryption — E2EE
- Participants’ devices control content keys. The transport server should not read ordinary messages.
- Confidentiality
- Limit who can access information, such as a conversation’s text.
- Security
- Prevent or limit reading, tampering, impersonation and unavailability against a defined adversary.
- Privacy and data minimisation
- Reduce information about you that can be observed, retained or linked.
- Metadata
- Data around the exchange: accounts, IP, timing, volume, devices or groups.
- Telemetry
- Data an application sends about its operation, such as errors or usage.
- Pseudonymity
- Use an identity different from your civil identity. It can still be linked to you.
- Anonymity
- A defined adversary cannot reasonably distinguish you within the relevant set of users.
- Network anonymity
- Reduce the ability to link traffic to your network address or its destination.
- Unlinkability
- Make it difficult to link two identities, relationships or activities.
- Traffic analysis
- Infer information from timing, sizes, volumes and paths without reading text.
- Forward secrecy — PFS
- Keys compromised later should not reveal old messages protected by deleted ephemeral keys.
- Post-compromise security
- A session can regain confidentiality after temporary state theft and safe key evolution.
- Key verification
- Check that the key used matches the key expected for your contact.
- Threat model
- Specify what you protect, from whom, and under which constraints.