This invention relates to a method for broadcasting digital data to a targeted set of reception terminals in which said data are previously scrambled by a series of control words transmitted in a conditional access control message.This method comprises the following steps: on transmission, particularise said access control message using a reversible function F for which the inverse function F−1 is executable only in terminals in the targeted set, and on reception, redetermine the original access control message in each terminal in the targeted set using said inverse function.