An encryption system (1) and a method for encrypting and decrypting sensitive data during a data interchange between at least two electronic appliances communicating with one another. The encryption system (1) has a data stream module (2) for providing a synchronous data stream as raw material for key generation, a data module (5) for preparing the data for the encryption/decryption, a key generator (6) to which an agreed information portion of the data stream from the data stream module (2) is supplied, an encryption/decryption unit (7) which is connected to the data module (5) and to the key generator (6) and which encrypts/decrypts the sensitive data using a keyword, and an output unit (7) for forwarding the encrypted/decrypted data, the key generator (6) taking the data stream supplied to it and producing a respective keyword for each message which is to be encrypted/decrypted simultaneously on the appliances communicating with one another.