Method for conditioning and controlling the access to hierarchical coding content, and processor and transmitter for said method The present invention relates to a method for conditioning and controlling access to scrambled hierarchically encoded content, a processor and a transmitter for this method. Scrambled hierarchically encoded content is a multimedia programme encoded and scrambled by components, the components of which are furthermore organized hierarchically so as to correspond to ordered levels of completeness of said content. That considered notion of completeness of the content depends on the context of the application of the method; a non-limiting list of examples thereof will be given later. A multimedia programme encoded and scrambled by components is a stream formed by at least elementary information streams li to lk, where k is an integer greater than or equal to two. Typically, each elementary information stream l1 to lk is transported by a data channel C1 to Ck respectively. These elementary information streams 11to lk are time-synchronized, one with the other. In scrambled hierarchically encoded content, these elementary streams, or components, are furthermore organized hierarchically one with respect to the other as follows: - elementary information stream li corresponds to the lowest level of completeness of the content and contains video or audio type information items \ intended to be used by a multimedia device, after descrambling, in order to be rendered directly comprehensible and intelligible by a human being, without it being necessary to add information items I2 to Ik therein, elementary information stream li being scrambled with a control word CW1, - elementary information stream li, for i strictly greater than 1, corresponds to a level of completeness i higher than the level of completeness i-1 of elementary information stream li-i, and directly improving it, elementary information stream I| containing information items Ij, intended to be used by the multimedia device, after descrambling, at the same time as information items11 to 11.1 in order that the combination of information items h to li thus produced is directly comprehensible and intelligible by a human being, information items li completing information items 1-1so that information items h can gradually be completed by information items I2 and successive information items, in that order, thereby making possible the use, by a multimedia device, of the multimedia programme in k different levels of completeness, the level of completeness increasing as index i increases, each elementary information stream li being scrambled with a control word CW1 that is different from control words CW1, where [ is different from i. A multimedia programme can be a television programme, a film or any other multimedia content intended to be played by a multimedia device. The multimedia device is, for example, a television set when the multimedia programme is a television programme or a film. When the multimedia programme is made up of only audio content, the multimedia device can be a simple hi-fi system. The information items are said to be directly comprehensible and intelligible by a human being when they are played by a multimedia device if this human being is capable of perceiving and understanding the information items reproduced by the multimedia device without the aid of additional electronic devices. The applicant knows of methods for controlling access to content encoded and scrambled by components, but without a hierarchical relationship, including: - the reception of messages ECM1 (Entitlement Control Message), each message ECM1 containing access conditions CA1 and a first cryptogram (CW1)cEi obtained by enciphering control word CW1 with an operating key CE1, - the transmission at least of message ECMk to a security processor, - the comparison, by the security processor, of access conditions CAk contained in message ECMk with access entitlements TA recorded beforehand in the security processor, and - the deciphering, by the security processor, of first cryptogram (CWk)cEk contained in message ECMk with the aid of operating key CEk only if access conditions CAk correspond to the access entitlements TA and, otherwise, interruption of the processing of received message ECMk. The known methods also include: - the comparison of each access condition CA, for i strictly less than k, with the access entitlements TA recorded beforehand in the security processor, and - the deciphering of first cryptogram (CWi)cEi contained in message ECMj only if access conditions CAi correspond to the access entitlements TA recorded beforehand. Typically, the operating keys CEi and the access entitlements TA are updated regularly, for example monthly, by using messages EMMi (Entitlement Management Message). So as to simplify this management, several components can share the same operating key. Hereafter in the text, conventional terminology is adopted, as used in the technical field of broadcasting of scrambled multimedia programmes to a multitude of receivers. Thus, terms such as "control word", "ECM" or "EMM" message are not defined here in more detail. For a better understanding with regard to the terminology specific to this technical field, reference may be made to the following document; "FUNCTIONAL MODEL OF A CONDITIONAL ACCESS SYSTEM" EBU REVIEW-TECHNICAL EUROPEAN BROADCASTING UNION. BRUSSELS, BE, no 266 21 December 1995. A security processor is typically a secure programmable computer. If it is detachable, it can be presented in many forms such as, as is common, a smart card, but also those of a dongle, a USB key or other more recent formats of detachable storage modules. The variety of these media and the objective of allowing them to make use of the same content in a manner that is transparent for the user, make it desirable today to minimize the computation power required to implement the methods for controlling access to content encoded and scrambled by hierarchical components. The invention aims to meet this requirement by proposing a method for controlling access to content encoded and scrambled by hierarchical components, requiring a reduced computational power as compared with the known methods. The invention therefore relates to an access control method referred to as hierarchical, including: - the reception and transmission to the security processor of second cryptograms (CW1)Ki, for i included between 1 and k-1, which are obtained by enciphering control words C1i to CWk-1 with keys K1 to Kk-1 respectively, which are constructed with at least a part of the set formed by information present in EC1VIk and by operating l