Secure messaging needs to meet these five requirements as much as possible: 1. Anti-Forgery Anti-Forgery ensures that the sender of a message is verifiable and the message has not been tampered with. 2. End-to-End Encryption End-to-end encryption ensures that only the sender and receiver can decrypt and read the message content, protecting it from unauthorized access by servers or other network devices. 3. Forward Secrecy Forward secrecy ensures that even if the current key is compromised, historical messages cannot be decrypted, since each message uses a new encryption key, which is deleted after use. 4. Break-in Recovery Break-in Recovery ensures that if the current key is compromised, future messages cannot be decrypted, and the system can recover from the attack. This feature is also known as backward secrecy. 5. Metadata Privacy Protecting the privacy of communication involves more than just protecting the content of messages; it also includes protecting the identities of the communication parties and other data. View quoted note →