AES加密过程是在一个4×4的字节矩阵上运作，这个矩阵又称为“体（state）”，其初值就是一个明文区块（矩阵中一个元素大小就是明文区块中的一个Byte）。（Rijndael加密法因支持更大的区块，其矩阵行数可视情况增加）加密时，各轮AES加密循环（除最后一轮外）均包含4个步骤：

1.AddRoundKey — 矩阵中的每一个字节都与该次回合金钥（round key）做XOR运算；每个子密钥由密钥生成方案产生。

2.SubBytes — 通过一个非线性的替换函数，用查找表的方式把每个字节替换成对应的字节。

3.ShiftRows — 将矩阵中的每个横列进行循环式移位。

4.MixColumns — 为了充分混合矩阵中各个直行的操作。这个步骤使用线性转换来混合每内联的四个字节。



最后一个加密循环中省略MixColumns步骤，而以另一个AddRoundKey取代。

-AES encryption process operates on a 44 byte matrix, this matrix is ​ ​ also known as " body (state), its initial value is a plaintext block (matrix element size is expressly block Byte ). (Rijndael encryption support larger blocks, the number of rows of the matrix, depending on the circumstances increase) encryption, each round of AES encryption cycle (except for the last one) contains four steps: 1.AddRoundKey- matrix a byte with the second leg (round key), key do XOR operation　each sub-key generated by the key generation program. 2.SubBytes- replaced by a non-linear function using a lookup table of each byte is replaced by the corresponding byte. 3.ShiftRows- each row of the matrix is ​ ​ a cyclic shift. 4.MixColumns- to be sufficiently mixed in the matrix, the operation of the respective straight. This step uses the linear conversion by mixing the four bytes of each inline. The last encryption cycle MixColumns step is omitted, and substituted with another A