低轮次DES体制的忠实性

The Faithfulness of The DES System Withwin Lower-rounds

对低轮次 DES体制的忠实性进行了分析。DES体制的所有构成要素中 ,S-盒起着十分关键的作用 ,我们先分析了 S-盒的性质 ,并利用所得到的性质 ,对 DES的忠实性进行了研究。证明了结果 :对于 5 6比特的全密钥而言 ,第一轮 DES不是忠实的 ,第二轮和第三轮的 DES是忠实的。

In this paper,we studied the faithfulness of the DES within lower rounds. Since the S-boxes are the only nonlinear component of the DES, we investigated the structure of the S-boxes at first and found some properties of the S-boxes.Our investigation shows that the first round DES is not faithful for the 56-bit full keys but is faithful for the 48-bit subkeys and that the 2-round and the 3-round DES are faithful for both the 48-bit subkeys and the 56-bit full keys.