securemessaging

Secure messaging refers to the practice of exchanging messages over digital networks with protections against eavesdropping, tampering, and impersonation. In typical designs, messages are encrypted on the sender’s device and decrypted only on the recipient’s device, so servers act mainly as transport relays and storage.

End-to-end encryption (E2EE) is central. The leading protocol is the Signal Protocol, which combines authenticated key exchange with the Double Ratchet algorithm to provide forward secrecy and post-compromise security. Group chats introduce extra complexity through rotating keys and member management.

Security goals include confidentiality, integrity, and authenticity of message content. Metadata—such as who communicates with whom and when—often remains exposed to servers, even when content is encrypted. Threat models cover passive and active attackers, as well as device compromise.

Implementation considerations include multi-device support, secure key storage, and user verification of keys. Backups can weaken security if not encrypted, and some apps only provide E2EE for one-to-one chats or require opt-in for cloud backups. Legal and policy debates continue around access requests.

History and standards: secure messaging evolved from PGP and off-the-record messaging (OTR). The Signal Protocol, developed by Open Whisper Systems in the 2010s, became widely adopted in apps such as Signal and WhatsApp. New efforts, including group-key protocols, aim to scale secure messaging.