A method for transmitting signaling information, such as cryptographic key synchronization information, over a data path of a network, the data path having an originating end and a terminating end. The method uses in-band signaling to transmit the signaling information from the originating end of the data path to the terminating end of the data path without consuming any bandwidth of the data path. More specifically, the method includes the steps of receiving user data to be transmitted over the data path and encrypting this user data with a cryptographic key, thereby generating cipher data. The method next includes processing the cipher data such that the cipher data includes the signaling information, and mapping the cipher data including the signaling information into a traffic unit for transmission over the data path.