A method for validating a road traffic control transaction. The method includes: storing a cryptographic key assigned to a transaction receiver, in the transaction receiver; recording an image of a vehicle; reading an identification of the vehicle in the recorded image by OCR and generating a control transaction thereof in the control station; generating a random key and encrypting the recorded image into authentication data with the random key and the cryptographic key in the control station; transmitting the recorded image, the control transaction, the random key and the authentication data to the transaction receiver; in the transaction receiver, encrypting the received recorded image into nominal authentication data with the received random key and the stored cryptographic key; and comparing the received authentication data with the nominal authentication data. The received control transaction is then validated when the received authentication data and the nominal authentication data are identical.