End-to-End Encryption E2E

End-to-end encryption (E2E) ensures that only the sender and recipient can read messages. The service provider (WhatsApp, Signal, etc.) cannot read messages even if they wanted to. It's built on asymmetric cryptography (public/private keys) and forward secrecy (keys rotate after each message). When you send a message, it's encrypted on your device with the recipient's public key. The server stores it encrypted. The recipient receives it and decrypts with their private key. The server never sees the decryption key.