Systems and methods for secure communication between a vehicle and a portable communication device. One system includes a vehicle access system included in the vehicle. The vehicle access system is configured to wirelessly receive a shuffled message from the portable communication device, de-shuffle the shuffled message at a bit level to obtain a message, wherein de-shuffling the shuffled message at a bit level includes exchanging one bit at a first indexed position within the shuffled message with one bit at a second indexed position within the shuffled message, and initiate a vehicle operation based on the message.