Abstract:
PURPOSE: An obfuscation method of a block encryption or decryption process and a device therefor are provided to implement an encryption system without exposing an encryption key. CONSTITUTION: A Obfuscation device in a block encryption or decryption process includes a Boolean function expression unit(610), a function integrating unit(620), and an encryption or decryption unit(630). A Boolean function expression unit expresses a relationship between an input process and an output process as a first Boolean function. The function integrating unit generates a second Boolean function by integrating the first Boolean function with an additional processing function. The encryption or decryption unit stores the second Boolean function as a digital format and encrypts or decrypts an input signal by applying the second Boolean function without exposing a secret key. [Reference numerals] (610) Boolean function expression unit; (620) Function integrating unit; (630) Encryption/decryption unit