通过本实验，使学生切实理解“S-盒”与“P-置换”的作用原理和实质差异，初步体会“多次迭代一个变换体”所能带来的诸如扩散性等密码学效果，培养和锻炼学生对于密码学中提出的一些技术指标进行探究的能力。-Through this experiment, so that students truly understand the " S-Box"　and " P-replacement"　in the role of theory and real differences in the initial experience of " multiple iterations of a transformation body"　can bring such as cryptography, such as spreading effect, foster and train students for cryptography to some of the technical indicators, the ability to explore.