Primary provisioning of a validation procedure for a terminal

The subject of the invention is a method for validating data sent by a source to a terminal on a medium. It includes sending data by the source to the terminal, on the medium, the calculation of a signature in the terminal, and the display on the terminal of an input prompt of a signature. The user of the terminal enters in response to the prompt a signature in the terminal; this signature is obtained by the user from the source or another reliable entity. The terminal receives the signature entered by the user, and compares the calculated signature and the signature entered by the user. If the comparison is positive, the terminal validates the data.