Patent attributes
Example embodiments relate to an encryption and decryption method for a conditional access content, including (a) extracting a marker (Mc) from a data packet (DP); (b) creating a first marking block including the marker (Mc) and a second padding value (PAD2); (c) encrypting the first marking block with a second encryption key (K2); (d) encrypting a second encrypted marking value (MK2) of the first encrypted marking block; (e) creating a mixed marking block including the second encrypted marking value (MK2) a the first encrypted padding element (PADK1); (f) decrypting the mixed marking block a device of the first encryption key (K1), in order to obtain a decrypted mixed marking block; (g) extracting a predetermined part of the decrypted mixed marking block; (h) comparing the extracted part with a reference value (Mc; PDV2); and (i) if the comparison leads to an identity, determining a new set of encryption parameters different to the first set of encryption parameters and repeating steps b) to h) in which the second set of encryption parameters is replaced by the new second set of encryption parameters.
