A method is provided for producing cryptographic keys, while a vehicle is in operation, for use in secure vehicle communications. The method may include obtaining unique entropy data from an entropy source based on dynamically changing, transient variables related to the operation of the vehicle, optionally in a driving mode. The method may include seeding a random number generator with the unique entropy data to generate at least one random number. A plurality of cryptographic keys are generated based on the at least one random number. A secure communication exchange may be established using the plurality of cryptographic keys. A non-transitory computer-readable medium is also provided having instructions embodied thereon that, when executed by a processor, perform the above operations as an algorithm in a vehicle.