密钥扩展模块的接口如图4.4。clk为系统时钟，kld为输入的加载信号，key为输入的128位密钥数据，wo_0, wo_1, wo_2, wo_3分别为输出的密钥列

the first task of the ”main” program aes_demo is a call to aes_init in Line 1. This initialization routine supplies 1 the actual en- and decryption functions (cipher and inv_cipher) with the expanded key schedule w,