The invention relates to a method of transmitting at least one additional piece of data D in a list of access control words CWi to a scrambled content transmitted by a content server of an operator to a user equipment (2) including a reception terminal (4) associated with a security processor (6), each control word CWi of said list being designed to descramble said contents during a determined cryptoperiod, this method includes the following steps: a) prior replacement of at least one of the control words of said list with a magnitude X resulting from the treatment of said additional piece of data D by a function G having a dual function H, and, at the reception of said list by the 15 reception terminal (4), b) retrieve said additional piece of data D by treating said magnitude X with dual function H.