Whysper is an experiment in creating truly private conversations on the web.
Every message sent on Whysper is protected by a combination of RSA and AES encryption. This means your messages are encrypted on your device and can only be decrypted by the person you are talking to. Servers and network only ever see random ciphertext.
After a guest joins the room, both users participate in a secure key exchange process to establish a shared encryption key. This key is used to encrypt and decrypt all messages in the chat. Only the two users know this key, and its never exposed to the server or any third party.