The invention relates to a method for generating a secret or key in a network. According to the invention, the network comprises at least one first client and one second client, having a common transmission channel between at least the first client and the second client. In addition, the first client has at least one circuit arrangement having at least one communications module for communication via the transmission channel and at least one additional module. Via the at least one additional module, the first client initiates the transmission of at least one first value sequence on the transmission channel, substantially synchronously with a transmission of at least one second value sequence by the second client, and generates a secret or a key on the basis of information relating to the at least one first value sequence and on the basis of a superimposed value sequence, resulting from superimposition of the at least one first value sequence and the at least one second value sequence on the transmission channel. The transmission of the at least one first value sequence by the at least one additional module is initiated in dependence on a first message received by the first client from the second client.