Method and device for controlling access to encrypted data

The invention relates to for controlling the deposits with control word encryption method and device for data, wherein the control word control information (ECM) is received from a safety module and returned to enciphered data - processing unit (STB). The method comprises the following steps: The receiving pokes the first control information comprises at least control word and time (ECM1), a receiving and first control information (ECM1) and control information (ECM2), the second message (pokes TS) comprises at least control word and time, determining according pokes the difference of the duration between the TS) and two machine control information (ECM1, ECM2 time); and duration time is lower than the preset time duration (CP); and utility counter counting gain; and time duration equal to the predetermined duration for or greater than that; and utility counter counting to reduce, is fixed in the utility counter valueThe dipole standby, loop control word to the processing unit (STB).