33轮SHACAL-2的差分非线性攻击

Differential-nonlinear attack on 33-round SHACAL-2

利用SHACAL-2的一个17轮差分非线性区分器,结合被猜测子密钥空间分割的方法和快速傅立叶变换,提出了一种攻击33轮SHACAL-2的新方法.该方法攻击33轮SHACAL-2需要244的选择明文、2496.6的33轮SHACAL-2加密和2502次算术运算,攻击成功概率为99%.与已有的结果相比较,新攻击有效地提高了单密钥下SHACAL-2的攻击轮数.

Based on a 17-round differential-nonlinear distinguisher of the SHACAL-2 encryption algorithm, a novel attack on 33-round SHACAL-2 is proposed by guessed subkey space division and Fast Fourier Transform （FFT）. Moreover, it is shown that differential nonlinear attack on 33-round SHACAL-2 requires a data complexity of about 244 chosen plaintexts, and a computational complexity of about 2^496.6 33-round SHACAL-2 encryptions and about 2^44 arithmetic operations. The success rate of this attack is about 0.99. Compared with previous results, this new attack effectively improves the numbers of attacked rounds of SHACAL-2 in a single key attack scenario.