METHOD FOR OBTAINING A SEQUENCE OF CRYPTOGRAPHIC KEYS

The invention relates to a method for obtaining a sequence of L cryptographic keys k1,m . ki,m, ki+1,m, kL,m in which, before an instant t1,m, a group of receivers establishes (140) a first connectionto a key server and receives, during said first connection, the information required to obtain the key k1,m, and, subsequently, for each index i between 2 and L: the group of receivers obtains (150)the subsequent key ki,m by running a key derivation algorithm initialised by means of the previous key ki-1,m and without using any information other than that received during the first connection; and the average run-time TCi,m of the key derivation algorithm by the group of receivers in order to obtain the key ki,m is higher than 0,2Vi-1,m., where V1-i,m is the duration of the validity intervalof the previous key ki-1,m. 一种用于获得L个加密密钥k1,m,ki,m,ki+1,m,kL,m的序列的方法，其中：在时刻t1,m之前，接收器组建立(140)到密钥服务器的第一连接，并在该第一连接期间接收获得所述密钥k1,m所需的信息，然后对于介于2至L的每个下标i：所述接收器组通过使用之前的密钥ki-1,m进行初始化的密钥推导算法来获得(150)之后的密钥ki,m，而无需借助于在所述第一连接期间接收到的信息以外的信息；以及