The present disclosure describes systems and methods of generating a cryptographic session key based on a known master key shared between a sender communicator and a receiver communicator in a communication network. In one example, a method includes receiving a request from the receiver communicator, by the sender communicator, to establish a communication session between the sender and the receiver communicator. The method further includes generating an open random number signal at the sender communicator and combining the generated open random number signal with the known master key to generate the cryptographic session key.