English to French Tech/Engineering Patents (in a patent) a whitebox descrambler

wherein a first block cipher round module uses a part of a predefined bit length of the ciphertext (C) as the input ciphertext data and wherein subsequent block cipher round use an output data of a previous block cipher round module as the input ciphertext data.

Each iteration is called a round, and the repeated function is called a round function. Typical block ciphers have 4 to 32 rounds.

Each block of ciphertext C is processed over 'n' rounds into the plaintext message 'M'. Each round 'r' receives its own round key 'RKr' as input, which is calculated from the original key 'K' in a key schedule module 501. In whitebox cryptography, each block cipher round module 4011,4012 is typically implemented using a sequence of table lookup operations hiding the value of the key 'K' and the roundkeys 'RKr' .


A block cipher round module 4011,4012 as shown in Fig.3 is shown in more detail in Fig.4. The block cipher round
function 401 contains two modules that operate in sequence...