signaaliprotokollajärjestelmistä

signaaliprotokolla or signal protocol is a cryptographic protocol used for providing end-to-end encrypted communication. It is developed by Open Whisper Systems and is widely used by messaging applications such as WhatsApp, Signal, and Facebook Messenger.

The protocol is designed to ensure that only the sender and the intended recipient can read the messages exchanged. It uses a combination of asymmetric and symmetric cryptography to achieve this security. When two users initiate a conversation, they first establish a shared secret key through a process called the Double Ratchet Algorithm. This algorithm is a key component of the Signal Protocol and allows for forward secrecy and post-compromise security.

Forward secrecy means that if a long-term secret key is compromised, past messages remain secure. Post-compromise security ensures that even if a current session key is compromised, future messages will still be secure after a short period. The Double Ratchet Algorithm continuously generates new session keys, making it very difficult for an attacker to decrypt conversations even if they manage to intercept them.

The Signal Protocol also supports features like group messaging, ensuring that all participants in a group chat have their communications end-to-end encrypted. The protocol's open-source nature allows security experts to review its code and verify its security properties, contributing to its widespread trust and adoption in secure communication services.