An apparatus is equipped with a deciphering round key generator to successively generate in real time at least a first and a second deciphering round key based on a deciphering key, and a deciphering unit coupled to the deciphering round key generator to successively employ the real time successively generated deciphering round keys to incrementally decipher a ciphered text. The deciphering round key generator at least generates the second deciphering round key in real time while the deciphering unit deciphers the ciphered text employing the real time generated first deciphering round key. At a result, deciphering round keys may be generated in a much more efficient manner on an as needed basis.