Personalized whitebox descramblers

Abstract

The invention prevents intercepted keys from being used in unauthorized whitebox descrambler modules for the decryption of a ciphertext. Hereto a receiver with a personalized whitebox descrambler is proposed, whereby a part of the descrambling operation of the personalized descrambler is performed in a preprocessing module external to the descrambler.

1 - 36 . (canceled) 
     
     
         37 . A descrambler, comprising:
 a processor configured to:
 receive a transformed key; 
 generate an output of a descrambling operation by applying a second part of the descrambling operation, comprising:
 partitioning the transformed key into a plurality of transformed key parts for a plurality of block cipher round modules; 
 for each of the plurality of transformed key parts, receiving, in a corresponding block cipher round module, input ciphertext data and selecting, based on the transformed key part.