1. A method for decrypting encrypted audio/video content in a decoder comprising at least a descrambler and a security module, said decryption being carried out by the descrambler using at least one final control word, said method comprising: receiving, by the descrambler, the encrypted audio/video content; converting, by the descrambler, one of at least two different control words to a first final control word using at least a first cryptographic function, the one of the at least two different control words being transferred to the descrambler upon being selected by the security module based on at least a first of an internal setting allowing the security module to be uniquely identified, said cryptographic function yielding the first final control word for either of the at least two different control words; using, by the descrambler, the first final control word to decrypt at least a first part the encrypted audio/video content; converting, by the descrambler, a further control word of a further set of at least two different control words to a further final control word using at least the first cryptographic function, the further control word being transferred to the descrambler upon being selected by the security module based on at least a second part of the internal setting, the second part of the internal setting being different from the first part of the internal setting, said first cryptographic function yielding the further final control word for either of the two different control words of the further set of at least two different control words; and using, by the descrambler, the further final control word to decrypt at least a further part of the encrypted audio/video content.