1.AES的工作原理

Rijndael是一种灵活的算法，其块的大小可变（128bit、192bit或256bit），密钥大小可变（128bit、192bit或256bit），迭代次数与块和密钥大小有关，因此迭代次数也可变（10，12或14）。常见的Rijndael结构如下图所示。Rijndael不像DES那样在每个阶段中使用替换和置换，而是进行多重循环的替换（Substitution）、行移位（ShiftRow）、列混合（Mixcolumn）和密钥加（Key Add）操作。本文把术语AES和Rijndael视为等价，可交替使用，同时，如无特别说明假设块的大小为128位。

Rijndael首先将明文按字节分成列组。前4个字节组成第一列，接下来的4个字节组成第二列，依此类推，如下图所示。因为块的大小是128bit，那么就可以组成一个4×4的矩阵。

例：假设要发送的短消息为：“Bob look at this”。包括空格在内，这个消息正好为16个字节（表示成ASCII码为128bit）。
这个消息表示成十六进制为：42 6f 62 20 6c 6f 6f 6b 20 61 74 20 74 68 69 73。
写成4×4的矩阵形式为：
(426c20746f6f6168626f7469206b2073)\begin{pmatrix} 42& 6c & 20 & 74\\ 6f& 6f & 61 & 68\\ 62& 6f & 74 & 69\\ 20& 6b & 20 & 73 \end{pmatrix}⎝⎜⎜⎛​426f6220​6c6f6f6b​20617420​74686973​⎠⎟⎟⎞​

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2.AES加密操作

2.1替换操作

Rijndael使用的是一个S-盒（而不是像DES那样使用8个）。Rijndael的S-盒是一个16×16的矩阵，如下代码所示。列的每个元素作为输入用来指定S-盒的地址：前4位指定S-盒的行，后4位指定S-盒的列。由行和列所确定的S-盒位置的元素取代了明文矩阵中相应位置的元素。

//S盒
const unsigned char SBox[16][16] ={/* 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f *//*0*/{ 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76 },/*1*/{ 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0 },/*2*/{ 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15 },/*3*/{ 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75 },/*4*/{ 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84 },/*5*/{ 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf },/*6*/{ 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8 },/*7*/{ 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2 },/*8*/{ 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73 },/*9*/{ 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb },/*a*/{ 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79 },/*b*/{ 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08 },/*c*/{ 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a },/*d*/{ 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e },/*e*/{ 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf },/*f*/{ 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 }};

例：上述明文的矩阵为：(426c20746f6f6168626f7469206b2073)\begin{pmatrix} 42& 6c & 20 & 74\\ 6f& 6f & 61 & 68\\ 62& 6f & 74 & 69\\ 20& 6b & 20 & 73 \end{pmatrix}⎝⎜⎜⎛​426f6220​6c6f6f6b​20617420​74686973​⎠⎟⎟⎞​
经过S-盒替换后变为(2c50b792a8a8ef45aaa892f9b77fb78f)\begin{pmatrix} 2c & 50 & b7 & 92\\ a8 & a8 & ef & 45\\ aa & a8 & 92 & f9\\ b7 & 7f & b7 & 8f \end{pmatrix}⎝⎜⎜⎛​2ca8aab7​50a8a87f​b7ef92b7​9245f98f​⎠⎟⎟⎞​
(0x42的前4位为0x04，后4位为0x02，在S-盒中找到对应的元素即可，其他依此类推)

S-盒替换操作的代码如下：

void SBoxFunc(unsigned char inputText[][4], unsigned char inputTextEncrypt[][4])
{unsigned int row=0,column=0; for(int i=0;i<4;i++){for(int j=0;j<4;j++){row = (inputText[i][j] & 0xF0) >> 4;column = inputText[i][j]&0x0F;inputTextEncrypt[i][j] = SBox[row][column];}}
}

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2.2行移位操作

行移位操作是作用于S-盒的输出的，其中，列的4个行螺旋地左移，即第一行左移0个字节，第二行左移1个字节，第三行左移2个字节，第四行左移3个字节，如下图所示。从该图中可以看出，这使得列完全进行了重排，即在移位后的每列中，都包含有未移位前每个列的一个字节。

上述明文经S-盒变换后的矩阵为：
(2c50b792a8a8ef45aaa892f9b77fb78f)\begin{pmatrix} 2c & 50 & b7 & 92\\ a8 & a8 & ef & 45\\ aa & a8 & 92 & f9\\ b7 & 7f & b7 & 8f \end{pmatrix}⎝⎜⎜⎛​2ca8aab7​50a8a87f​b7ef92b7​9245f98f​⎠⎟⎟⎞​
经过行移位操作后，矩阵变为：
(2c50b792a8ef45a892f9aaa88fb77fb7)\begin{pmatrix} 2c & 50 & b7 & 92\\ a8 & ef & 45 & a8\\ 92 & f9 & aa & a8\\ 8f & b7 & 7f & b7 \end{pmatrix}⎝⎜⎜⎛​2ca8928f​50eff9b7​b745aa7f​92a8a8b7​⎠⎟⎟⎞​

行移位操作的实现代码如下所示：

//形参是一个4×4的矩阵
void ShiftRows(unsigned char inputTextEncrypt [][4])
{unsigned char temp = 0;for(int i=1;i<4;i++){for(int j=0;j<i;j++){temp = inputTextEncrypt[i][0];inputTextEncrypt[i][0] = inputTextEncrypt[i][1];inputTextEncrypt[i][1] = inputTextEncrypt[i][2];inputTextEncrypt[i][2] = inputTextEncrypt[i][3];inputTextEncrypt[i][3] = temp;}}
}

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2.3列混合操作

列混合操作是通过矩阵相乘来实现的。经移位后的矩阵与固定的矩阵（以十六进制表示）相乘，如下所示：(c0c1c3c4)=(02030101010203010101020303010102)(b0b1b2b4)\begin{pmatrix} c_0 \\ c_1 \\ c_3 \\ c_4 \end{pmatrix} = \begin{pmatrix} 02 & 03 & 01 & 01\\ 01 & 02 & 03 & 01\\ 01 & 01 & 02 & 03\\ 03 & 01 & 01 & 02 \end{pmatrix} \begin{pmatrix} b_0 \\ b_1 \\ b_2 \\ b_4 \end{pmatrix}⎝⎜⎜⎛​c0​c1​c3​c4​​⎠⎟⎟⎞​=⎝⎜⎜⎛​02010103​03020101​01030201​01010302​⎠⎟⎟⎞​⎝⎜⎜⎛​b0​b1​b2​b4​​⎠⎟⎟⎞​
注意：这个运算需要做GF(2n)GF(2^n)GF(2n)上的乘法，但由于所乘的因子是三个固定的元素02、03、01，所以这些乘法运算仍然是比较简单的，其中乘法运算所使用的模多项式为m(x)=x8+x4+x3+x+1m(x)=x^8+x^4+x^3+x+1m(x)=x8+x4+x3+x+1。设一个字节为(b7b6b5b4b3b2b1b0)(b_7b_6b_5b_4b_3b_2b_1b_0)(b7​b6​b5​b4​b3​b2​b1​b0​)，则有：
(b7b6b5b4b3b2b1b0)×′01′=(b7b6b5b4b3b2b1b0);(b7b6b5b4b3b2b1b0)×′02′=(b6b5b4b3b2b1b00)+(000b7b70b7b7);(b7b6b5b4b3b2b1b0)×′03′=(b7b6b5b4b3b2b1b0)×′01′⊕(b7b6b5b4b3b2b1b0)×′02′;(b_7b_6b_5b_4b_3b_2b_1b_0)\times '01'=(b_7b_6b_5b_4b_3b_2b_1b_0);\\ (b_7b_6b_5b_4b_3b_2b_1b_0)\times '02'=(b_6b_5b_4b_3b_2b_1b_00)+(000b_7b_70b_7b_7);\\ (b_7b_6b_5b_4b_3b_2b_1b_0)\times '03'=(b_7b_6b_5b_4b_3b_2b_1b_0)\times '01'\oplus(b_7b_6b_5b_4b_3b_2b_1b_0)\times '02';(b7​b6​b5​b4​b3​b2​b1​b0​)×′01′=(b7​b6​b5​b4​b3​b2​b1​b0​);(b7​b6​b5​b4​b3​b2​b1​b0​)×′02′=(b6​b5​b4​b3​b2​b1​b0​0)+(000b7​b7​0b7​b7​);(b7​b6​b5​b4​b3​b2​b1​b0​)×′03′=(b7​b6​b5​b4​b3​b2​b1​b0​)×′01′⊕(b7​b6​b5​b4​b3​b2​b1​b0​)×′02′;
这些操作保证了明文位经几个迭代轮后已高度打乱了，同时还保证输入与输出之间的关联很少了。这就是该算法安全性的两个重要特征。

例：上述行移位操作后的矩阵为：(2c50b792a8ef45a892f9aaa88fb77fb7)\begin{pmatrix} 2c & 50 & b7 & 92\\ a8 & ef & 45 & a8\\ 92 & f9 & aa & a8\\ 8f & b7 & 7f & b7 \end{pmatrix}⎝⎜⎜⎛​2ca8928f​50eff9b7​b745aa7f​92a8a8b7​⎠⎟⎟⎞​
对其进行列混合，则有
(a6c46fc34532a78d31943cb34b93d3d8)=(02030101010203010101020303010102)(2c50b792a8ef45a892f9aaa88fb77fb7)\begin{pmatrix} a6 & c4 & 6f & c3\\ 45 & 32 & a7 & 8d\\ 31 & 94 & 3c & b3\\ 4b & 93 & d3 & d8 \end{pmatrix} = \begin{pmatrix} 02 & 03 & 01 & 01\\ 01 & 02 & 03 & 01\\ 01 & 01 & 02 & 03\\ 03 & 01 & 01 & 02 \end{pmatrix} \begin{pmatrix} 2c & 50 & b7 & 92\\ a8 & ef & 45 & a8\\ 92 & f9 & aa & a8\\ 8f & b7 & 7f & b7 \end{pmatrix}⎝⎜⎜⎛​a645314b​c4329493​6fa73cd3​c38db3d8​⎠⎟⎟⎞​=⎝⎜⎜⎛​02010103​03020101​01030201​01010302​⎠⎟⎟⎞​⎝⎜⎜⎛​2ca8928f​50eff9b7​b745aa7f​92a8a8b7​⎠⎟⎟⎞​
计算一下(02030101)(2ca8928f)\begin{pmatrix} 02 & 03 & 01 & 01 \end{pmatrix} \begin{pmatrix} 2c \\ a8 \\ 92 \\ 8f \end{pmatrix}(02​03​01​01​)⎝⎜⎜⎛​2ca8928f​⎠⎟⎟⎞​
$$\begin{gathered} 02\times 2c=00000010\times 00101100=01011000\oplus 00000000=01011000; \\ 03\times a8=02\times a8(10101000)\oplus 01\times a8(10101000)=01010000\oplus 00011011\oplus 10101000=11100011; \\ 01\times 92=10010010; \\ 01\times 8f=10001111; \\ 01011000\oplus 11100011\oplus 10010010\oplus 10001111=10100110=a6 \end{gathered}$$
这样就算出了第一个值$a6$，其余的大家自己动手算一下就好。
注意：①$\oplus$是异或操作；②乘02的时候异或的是000b7b70b7b7000b_7b_70b_7b_7000b7​b7​0b7​b7​。

列混合步骤的代码如下所示：

//要乘的矩阵
const unsigned char GFMatrix[4][4] = {{0x02,0x03,0x01,0x01},{0x01,0x02,0x03,0x01},{0x01,0x01,0x02,0x03},{0x03,0x01,0x01,0x02}};
//下面的是矩阵相乘的操作
unsigned char GFMul01(unsigned char num)
{return num;
}unsigned char GFMul02(unsigned char num)
{unsigned char temp = num>>7&0xFF;if(temp==0x00)return num<<1&0xFF;else if(temp==0x01)return (num<<1&0xFF)^0x1B;
}unsigned char GFMul03(unsigned char num)
{return GFMul01(num)^GFMul02(num);
}unsigned char GFMulAll(unsigned char num1,unsigned char num2)
{if(num2==0x01)return GFMul01(num1);else if(num2==0x02)return GFMul02(num1);else if(num2==0x03)return GFMul03(num1);
}
//列混合实现代码
void ColumnMix(unsigned char inputTextEncrypt [][4],unsigned char inputTextColumnMix [][4])
{	for(int j=0;j<4;j++){for(int i=0;i<4;i++){inputTextColumnMix[i][j] = GFMulAll(inputTextEncrypt[0][j],GFMatrix[i][0])^GFMulAll(inputTextEncrypt[1][j],GFMatrix[i][1])^GFMulAll(inputTextEncrypt[2][j],GFMatrix[i][2])^GFMulAll(inputTextEncrypt[3][j],GFMatrix[i][3]);}}
}

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2.4密钥加操作

密钥加操作是每轮中的最后一个操作，是将以上结果与子密钥进行XOR逻辑运算，如下图所示。这完成了该算法的一次迭代。

例：经过列混合后，明文矩阵变为：
(a6c46fc34532a78d31943cb34b93d3d8)\begin{pmatrix} a6 & c4 & 6f & c3\\ 45 & 32 & a7 & 8d\\ 31 & 94 & 3c & b3\\ 4b & 93 & d3 & d8 \end{pmatrix}⎝⎜⎜⎛​a645314b​c4329493​6fa73cd3​c38db3d8​⎠⎟⎟⎞​
假设此时的轮密钥为：
(01a39012e1442011cc7304a9590630b4)\begin{pmatrix} 01 & a3 & 90 & 12\\ e1 & 44 & 20 & 11\\ cc & 73 & 04 & a9\\ 59 & 06 & 30 & b4 \end{pmatrix}⎝⎜⎜⎛​01e1cc59​a3447306​90200430​1211a9b4​⎠⎟⎟⎞​
则有
(a6c46fc34532a78d31943cb34b93d3d8)XOR(01a39012e1442011cc7304a9590630b4)=(a767ffd1a476879cfde7381a1295e36c)\begin{pmatrix} a6 & c4 & 6f & c3\\ 45 & 32 & a7 & 8d\\ 31 & 94 & 3c & b3\\ 4b & 93 & d3 & d8 \end{pmatrix} XOR \begin{pmatrix} 01 & a3 & 90 & 12\\ e1 & 44 & 20 & 11\\ cc & 73 & 04 & a9\\ 59 & 06 & 30 & b4 \end{pmatrix} = \begin{pmatrix} a7 & 67 & ff & d1\\ a4 & 76 & 87 & 9c\\ fd & e7 & 38 & 1a\\ 12 & 95 & e3 & 6c \end{pmatrix}⎝⎜⎜⎛​a645314b​c4329493​6fa73cd3​c38db3d8​⎠⎟⎟⎞​XOR⎝⎜⎜⎛​01e1cc59​a3447306​90200430​1211a9b4​⎠⎟⎟⎞​=⎝⎜⎜⎛​a7a4fd12​6776e795​ff8738e3​d19c1a6c​⎠⎟⎟⎞​
$a6\oplus 01=a7;c4\oplus a3=67;$依此类推

密钥加操作的代码如下：

void RoundKeyXOR(unsigned char inputTextColumnMix [][4],unsigned char RoundKey [][4],unsigned char inputText[][4])
{for(int i=0;i<4;i++){for(int j=0;j<4;j++){inputText[i][j] = inputTextColumnMix[i][j]^RoundKey[i][j];}}
}

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3.AES的密钥生成

密钥是按矩阵的列进行分组的，然后添加40个新列来进行扩充。如果前4列（即由密钥给定的那些列）为$W(0)$、$W(1)$、$W(2)$和$W(3)$，那么新列以递归方式产生。
如果$i$不是4的倍数，那么第$i$列由如下等式确定：$$W(i)=W(i-4)XORW(i-1)$$如果$i$是4的倍数，那么第$i$列由如下等式确定：$$W(i)=W(i-4)XORT[W(i-1)]$$其中$T[W(i-1)]$是$W(i-1)$的一种转换形式，按一下方式实现的：
（1）循环地将$W(i-1)$的元素移位，每次一个字节，也就是说，$abcd$变成$bcda$（一个字母是一个字节大小）。
（2）将这4个字节作为S-盒的输入，输出新的4个字节$efgh$。
（3）计算一轮的常量r(i)=2(i−4)/4r(i)=2^{(i-4)/4}r(i)=2(i−4)/4。
（4）这样生成转换后的列：$[eXORr(i),f,g,h]$。
第$i$轮的轮密钥组成了列$W(4i)$、$W(4i+1)$、$W(4i+2)$和$W(4i+3)$。过程如下图所示：

例：如果初始的128bit密钥为（以十六进制表示）：3ca10b21、57f01916、902e1380和acc107bd。
那么4个初始值为$W(0)=3ca10b21,W(1)=57f01916,W(2)=902e1380,W(3)=acc107bd$。
即(3c5790aca1f02ec10b191307211680bd)\begin{pmatrix} 3c & 57 & 90 & ac\\ a1 & f0 & 2e & c1\\ 0b & 19 & 13 & 07\\ 21 & 16 & 80 & bd \end{pmatrix}⎝⎜⎜⎛​3ca10b21​57f01916​902e1380​acc107bd​⎠⎟⎟⎞​下一个子密钥段为$W(4)$，由于4是4的倍数，所以$$W(4)=W(0)XORT[W(3)]$$ $T[W(3)]$的计算步骤如下：
（1）循环地将$W(3)$的元素移位：$acc107bd$变成了$c107bdac$。
（2）将$c107bdac$作为S-盒的输入，输出$78857a91$。
（3）计算一轮的常量r(4)=20=01r(4)=2^0=01r(4)=20=01（以十六进制表示）。
（4）将$r(4)$与第一个字节78进行XOR逻辑运算：$78XOR01=79$。
因此，$T[W(3)]=79857a91$，并且$$W(4)=3ca10b21XOR79857a91=456471b0$$
其余的3个子密钥段计算如下：$$W(5)=W(1)XORW(4)=57f01916XOR456471b0=129468a6；$$ $$W(6)=W(2)XORW(5)=902c1380XOR129468a6=82b87b26；$$ $$W(7)=W(3)XORW(6)=acc107bdXOR82b87b26=2e797c9b；$$
于是，第一轮的密钥为：$456471b0129468a682b87b262e797c9b$。

AES密钥生成的代码如下：

//循环中常量r的值
const unsigned char R[10] = {0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80,0x1B,0x36};
//密钥生成的过程
void CipherKeyExtended(unsigned char cipherKey[][4] , unsigned char cipherKeySum[][44])
{for(int i=0;i<4;i++){for(int j=0;j<4;j++){cipherKeySum[i][j] = cipherKey[i][j];}}unsigned char tempColumnLast[4] = {0};for(int j=4;j<44;j++){if(j%4!=0){for(int i=0;i<4;i++){cipherKeySum[i][j] = cipherKeySum[i][j-4]^cipherKeySum[i][j-1];}}else{for(int i=0;i<4;i++){tempColumnLast[i] = cipherKeySum[i][j-1];}unsigned char temp = tempColumnLast[0];for(int k=0;k<3;k++){tempColumnLast[k] = tempColumnLast[k+1];}tempColumnLast[3] = temp;for(int k=0;k<4;k++){tempColumnLast[k] = SBox[(tempColumnLast[k]&0xF0)>>4][tempColumnLast[k]&0x0F];}tempColumnLast[0] = tempColumnLast[0]^R[j/4-1];for(int i=0;i<4;i++){cipherKeySum[i][j] = cipherKeySum[i][j-4]^tempColumnLast[i];}}}
}

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4.AES解密操作

4.1逆行移位

行移位操作是列的4个行螺旋地左移，则逆行移位操作就是列的4个行螺旋地右移，即第一行右移0个字节，第二行右移1个字节，第三行右移2个字节，第四行右移3个字节，如下图所示。

例：假设有一个矩阵为：(1ddcd4071843222bf640102565472faf)\begin{pmatrix} 1d & dc & d4 & 07\\ 18 & 43 & 22 & 2b\\ f6 & 40 & 10 & 25\\ 65 & 47 & 2f & af \end{pmatrix}⎝⎜⎜⎛​1d18f665​dc434047​d422102f​072b25af​⎠⎟⎟⎞​对其进行逆行移位操作，则得到矩阵：(1ddcd4072b1843221025f640472faf65)\begin{pmatrix} 1d & dc & d4 & 07\\ 2b & 18 & 43 & 22\\ 10 & 25 & f6 & 40\\ 47 & 2f & af & 65 \end{pmatrix}⎝⎜⎜⎛​1d2b1047​dc18252f​d443f6af​07224065​⎠⎟⎟⎞​

逆行移位操作的代码如下：

void ReShiftRows(unsigned char inputTextEncrypt [][4])
{unsigned char temp = 0;for(int i=1;i<4;i++){for(int j=0;j<i;j++){temp = inputTextEncrypt[i][3];inputTextEncrypt[i][3] = inputTextEncrypt[i][2];inputTextEncrypt[i][2] = inputTextEncrypt[i][1];inputTextEncrypt[i][1] = inputTextEncrypt[i][0];inputTextEncrypt[i][0] = temp;}}
}

---

4.2逆S-盒替换

逆S-盒替换使用的S-盒也是一个$16\times 16$的矩阵，如下代码所示。列的每个元素作为输入用来指定S-盒的地址：前4位指定S-盒的行，后4位指定S-盒的列。由行和列所确定的S-盒位置的元素取代了密文矩阵中相应位置的元素。

//逆S盒
const unsigned char ReSBox[16][16] = {/* 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f */{0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb},{0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb},{0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e},{0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25},{0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92},{0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84},{0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06},{0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b},{0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73},{0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e},{0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b},{0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4},{0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f},{0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef},{0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61},{0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d}}; 

例：假设密文矩阵为：(2c50b792a8a8ef45aaa892f9b77fb78f)\begin{pmatrix} 2c & 50 & b7 & 92\\ a8 & a8 & ef & 45\\ aa & a8 & 92 & f9\\ b7 & 7f & b7 & 8f \end{pmatrix}⎝⎜⎜⎛​2ca8aab7​50a8a87f​b7ef92b7​9245f98f​⎠⎟⎟⎞​经过逆S-盒替换操作后，矩阵变为：(426c20746f6f6168626f7469206b2073)\begin{pmatrix} 42& 6c & 20 & 74\\ 6f& 6f & 61 & 68\\ 62& 6f & 74 & 69\\ 20& 6b & 20 & 73 \end{pmatrix}⎝⎜⎜⎛​426f6220​6c6f6f6b​20617420​74686973​⎠⎟⎟⎞​

逆S-盒替换操作的代码如下：

void ReSBoxFunc(unsigned char inputText[][4],unsigned char inputTextEncrypt[][4])
{unsigned int row=0,column=0; for(int i=0;i<4;i++){for(int j=0;j<4;j++){row = (inputText[i][j] & 0xF0) >> 4;column = inputText[i][j]&0x0F;inputTextEncrypt[i][j] = ReSBox[row][column];}}
}

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4.3密钥加操作

解密时执行的密钥加操作和加密时采用的密钥加操作是相同的，注意加密和解密使用的是同一组轮密钥即可。

4.4逆列混合操作

逆列混合操作是通过矩阵相乘来实现的。将密文矩阵与固定的矩阵（以十六进制表示）相乘，如下所示。(c0c1c2c3)=(0E0B0D09090E0B0D0D090E0B0B0D090E)(b0b1b2b3)\begin{pmatrix} c_0 \\ c_1 \\ c_2 \\ c_3 \end{pmatrix} = \begin{pmatrix} 0E & 0B & 0D & 09\\ 09 & 0E & 0B & 0D\\ 0D & 09 & 0E & 0B\\ 0B & 0D & 09 & 0E \end{pmatrix} \begin{pmatrix} b_0 \\ b_1 \\ b_2 \\ b_3 \end{pmatrix}⎝⎜⎜⎛​c0​c1​c2​c3​​⎠⎟⎟⎞​=⎝⎜⎜⎛​0E090D0B​0B0E090D​0D0B0E09​090D0B0E​⎠⎟⎟⎞​⎝⎜⎜⎛​b0​b1​b2​b3​​⎠⎟⎟⎞​下面介绍如何进行相乘。
假设存在一个字节$B$，则有：
B×′09′=B×(′08′⊕′01′)=(B×′02′×′02′×′02′)⊕(B×′01′);B×′0B′=B×(′08′⊕′02′⊕′01′)=(B×′02′×′02′×′02′)⊕(B×′02′)⊕(B×′01′);B×′0D′=B×(′08′⊕′04′⊕′01′)=(B×′02′×′02′×′02′)⊕(B×′02′×′02′)⊕(B×′01′);B×′0E′=B×(′08′⊕′04′⊕′02′)=(B×′02′×′02′×′02′)⊕(B×′02′×′02′)⊕(B×′02′);B\times '09'=B\times ('08'\oplus '01')=(B\times'02'\times '02'\times '02')\oplus (B\times '01');\\ B\times '0B'=B\times ('08'\oplus '02'\oplus '01')=(B\times'02'\times '02'\times '02')\oplus (B\times'02')\oplus (B\times '01');\\ B\times '0D'=B\times ('08'\oplus '04'\oplus '01')=(B\times'02'\times '02'\times '02')\oplus (B\times'02'\times '02')\oplus (B\times '01');\\ B\times '0E'=B\times ('08'\oplus '04'\oplus '02')=(B\times'02'\times '02'\times '02')\oplus (B\times'02'\times '02')\oplus (B\times '02');\\ B×′09′=B×(′08′⊕′01′)=(B×′02′×′02′×′02′)⊕(B×′01′);B×′0B′=B×(′08′⊕′02′⊕′01′)=(B×′02′×′02′×′02′)⊕(B×′02′)⊕(B×′01′);B×′0D′=B×(′08′⊕′04′⊕′01′)=(B×′02′×′02′×′02′)⊕(B×′02′×′02′)⊕(B×′01′);B×′0E′=B×(′08′⊕′04′⊕′02′)=(B×′02′×′02′×′02′)⊕(B×′02′×′02′)⊕(B×′02′);

例：假设密文矩阵为：(6065676379e7f90046a37e5274cc1398)\begin{pmatrix} 60 & 65 & 67 & 63\\ 79 & e7 & f9 & 00\\ 46 & a3 & 7e & 52\\ 74 & cc & 13 & 98 \end{pmatrix}⎝⎜⎜⎛​60794674​65e7a3cc​67f97e13​63005298​⎠⎟⎟⎞​经过逆列混合操作后，得:(a28b0ef75b074364d28cea8f00ed54b5)=(0E0B0D09090E0B0D0D090E0B0B0D090E)(6065676379e7f90046a37e5274cc1398)\begin{pmatrix} a2 & 8b & 0e & f7\\ 5b & 07 & 43 & 64\\ d2 & 8c & ea & 8f\\ 00 & ed & 54 & b5 \end{pmatrix} = \begin{pmatrix} 0E & 0B & 0D & 09\\ 09 & 0E & 0B & 0D\\ 0D & 09 & 0E & 0B\\ 0B & 0D & 09 & 0E \end{pmatrix} \begin{pmatrix} 60 & 65 & 67 & 63\\ 79 & e7 & f9 & 00\\ 46 & a3 & 7e & 52\\ 74 & cc & 13 & 98 \end{pmatrix}⎝⎜⎜⎛​a25bd200​8b078ced​0e43ea54​f7648fb5​⎠⎟⎟⎞​=⎝⎜⎜⎛​0E090D0B​0B0E090D​0D0B0E09​090D0B0E​⎠⎟⎟⎞​⎝⎜⎜⎛​60794674​65e7a3cc​67f97e13​63005298​⎠⎟⎟⎞​下面计算：(0E0B0D09)(60794674)\begin{pmatrix} 0E & 0B & 0D & 09 \end{pmatrix} \begin{pmatrix} 60 \\ 79 \\ 46 \\ 74 \end{pmatrix}(0E​0B​0D​09​)⎝⎜⎜⎛​60794674​⎠⎟⎟⎞​
60×′0E′=(01100000×′02′×′02′×′02′)⊕(01100000×′02′×′02′)⊕(01100000×′02′)=(11000000×′02′×′02′)⊕(11000000×′02′)⊕(11000000)=(10011011×′02′)⊕(10011011)⊕(11000000)=(00101101)⊕(10011011)⊕(11000000)=0111011060\times '0E'=(01100000\times '02'\times '02'\times '02')\oplus (01100000\times '02'\times '02')\oplus(01100000\times '02')\\ =(11000000\times '02'\times '02')\oplus (11000000\times '02') \oplus (11000000)\\ =(10011011\times '02')\oplus (10011011)\oplus (11000000)\\ =(00101101)\oplus (10011011)\oplus (11000000)=0111011060×′0E′=(01100000×′02′×′02′×′02′)⊕(01100000×′02′×′02′)⊕(01100000×′02′)=(11000000×′02′×′02′)⊕(11000000×′02′)⊕(11000000)=(10011011×′02′)⊕(10011011)⊕(11000000)=(00101101)⊕(10011011)⊕(11000000)=01110110
79×′0B′=(01111001×′02′×′02′×′02′)⊕(01111001×′02′)⊕(01111001×′01′)=(11110010×′02′×′02′)⊕(11110010)⊕(01111001)=(11111111×′02′)⊕(11110010)⊕(01111001)=(11100101)⊕(11110010)⊕(01111001)=0110111079\times '0B'=(01111001\times '02'\times '02'\times '02')\oplus (01111001\times '02')\oplus (01111001\times '01')\\ =(11110010\times '02'\times '02')\oplus (11110010)\oplus (01111001)\\ =(11111111\times '02')\oplus (11110010)\oplus (01111001)\\ =(11100101)\oplus (11110010)\oplus (01111001)=0110111079×′0B′=(01111001×′02′×′02′×′02′)⊕(01111001×′02′)⊕(01111001×′01′)=(11110010×′02′×′02′)⊕(11110010)⊕(01111001)=(11111111×′02′)⊕(11110010)⊕(01111001)=(11100101)⊕(11110010)⊕(01111001)=01101110
46×′0D′=(01000110×′02′×′02′×′02′)⊕(01000110×′02′×′02′)⊕(01000110×′01′)=(10001100×′02′×′02′)⊕(10001100×′02′)⊕(01000110)=(00000011×′02′)⊕(00000011)⊕(01000110)=(00000110)⊕(00000011)⊕(01000110)=0100001146\times '0D'=(01000110\times '02'\times '02'\times '02')\oplus (01000110\times '02'\times '02')\oplus (01000110\times '01')\\ =(10001100\times '02'\times '02')\oplus(10001100\times '02')\oplus (01000110)\\ =(00000011\times '02')\oplus (00000011)\oplus (01000110)\\ =(00000110)\oplus (00000011)\oplus (01000110)=01000011 46×′0D′=(01000110×′02′×′02′×′02′)⊕(01000110×′02′×′02′)⊕(01000110×′01′)=(10001100×′02′×′02′)⊕(10001100×′02′)⊕(01000110)=(00000011×′02′)⊕(00000011)⊕(01000110)=(00000110)⊕(00000011)⊕(01000110)=01000011
74×′09′=(01110100×′02′×′02′×′02′)⊕(01110100×′01′)=(11101000×′02′)⊕(01110100)=(11001011×′02′)⊕(01110100)=(10001101)⊕(01110100)=1111100174\times '09'=(01110100\times '02'\times '02'\times '02')\oplus (01110100\times '01')\\ =(11101000\times '02')\oplus (01110100)\\ =(11001011\times '02')\oplus (01110100)\\ =(10001101)\oplus (01110100)=1111100174×′09′=(01110100×′02′×′02′×′02′)⊕(01110100×′01′)=(11101000×′02′)⊕(01110100)=(11001011×′02′)⊕(01110100)=(10001101)⊕(01110100)=11111001
$$01110110\oplus 01101110\oplus 01000011\oplus 11111001=10100010=a2$$

逆列混合的代码如下：

unsigned char GFMul04(unsigned char num)
{unsigned char temp=num;for(int i=0;i<2;i++){temp = GFMul02(temp);}return temp;
}unsigned char GFMul08(unsigned char num)
{unsigned char temp=num;for(int i=0;i<3;i++){temp = GFMul02(temp);}return temp;
}unsigned char GFMul09(unsigned char num)
{return GFMul08(num)^GFMul01(num);
}unsigned char GFMul0B(unsigned char num)
{return GFMul08(num)^GFMul02(num)^GFMul01(num);
}unsigned char GFMul0D(unsigned char num)
{return GFMul08(num)^GFMul04(num)^GFMul01(num);
}unsigned char GFMul0E(unsigned char num)
{return GFMul08(num)^GFMul04(num)^GFMul02(num);
}unsigned char ReGFMulAll(unsigned char num1,unsigned char num2)
{if(num2==0x09)return GFMul09(num1);else if(num2==0x0B)return GFMul0B(num1);else if(num2==0x0D)return GFMul0D(num1);else if(num2==0x0E)return GFMul0E(num1);
}void ReColumnMix(unsigned char inputTextColumnMix [][4],unsigned char inputTextEncrypt [][4])
{for(int j=0;j<4;j++){for(int i=0;i<4;i++){inputTextEncrypt[i][j] = ReGFMulAll(inputTextColumnMix[0][j],ReGFMatrix[i][0])^ReGFMulAll(inputTextColumnMix[1][j],ReGFMatrix[i][1])^ReGFMulAll(inputTextColumnMix[2][j],ReGFMatrix[i][2])^ReGFMulAll(inputTextColumnMix[3][j],ReGFMatrix[i][3]);}}
}

---

5.完整代码

//aes.h
#ifndef _AES_H_
#define _AES_H_#include<stdio.h>//S盒
const unsigned char SBox[16][16] ={/* 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f *//*0*/{ 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76 },/*1*/{ 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0 },/*2*/{ 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15 },/*3*/{ 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75 },/*4*/{ 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84 },/*5*/{ 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf },/*6*/{ 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8 },/*7*/{ 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2 },/*8*/{ 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73 },/*9*/{ 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb },/*a*/{ 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79 },/*b*/{ 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08 },/*c*/{ 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a },/*d*/{ 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e },/*e*/{ 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf },/*f*/{ 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 }};//逆S盒
const unsigned char ReSBox[16][16] = {/* 0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f */{0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb},{0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb},{0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e},{0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25},{0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92},{0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84},{0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06},{0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b},{0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73},{0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e},{0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b},{0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4},{0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f},{0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef},{0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61},{0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d}}; const unsigned char GFMatrix[4][4] = {{0x02,0x03,0x01,0x01},{0x01,0x02,0x03,0x01},{0x01,0x01,0x02,0x03},{0x03,0x01,0x01,0x02}};const unsigned char ReGFMatrix[4][4] = 	{{0x0E,0x0B,0x0D,0x09},{0x09,0x0E,0x0B,0x0D},{0x0D,0x09,0x0E,0x0B},{0x0B,0x0D,0x09,0x0E}};	const unsigned char R[10] = {0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80,0x1B,0x36};
#endif

#include "aes.h"//S盒置换
void SBoxFunc(unsigned char inputText[][4], unsigned char inputTextEncrypt[][4]);
//S盒逆置换
void ReSBoxFunc(unsigned char inputText[][4],unsigned char inputTextEncrypt[][4]);
//行移位
void ShiftRows(unsigned char inputTextEncrypt [][4]);
//逆行移位
void ReShiftRows(unsigned char inputTextEncrypt [][4]);
//列混合
unsigned char GFMul01(unsigned char num);
unsigned char GFMul02(unsigned char num);
unsigned char GFMul03(unsigned char num);
unsigned char GFMulAll(unsigned char num1,unsigned char num2);
void ColumnMix(unsigned char inputTextEncrypt [][4],unsigned char inputTextColumnMix [][4]);
//逆列混合
unsigned char GFMul04(unsigned char num);
unsigned char GFMul08(unsigned char num);
unsigned char GFMul09(unsigned char num);
unsigned char GFMul0B(unsigned char num);
unsigned char GFMul0D(unsigned char num);
unsigned char GFMul0E(unsigned char num);
unsigned char ReGFMulAll(unsigned char num1,unsigned char num2);
void ReColumnMix(unsigned char inputTextColumnMix [][4],unsigned char inputTextEncrypt [][4]);
//轮密钥异或
void RoundKeyXOR(unsigned char inputTextColumnMix [][4],unsigned char RoundKey [][4],unsigned char inputText[][4]);
//密钥扩展
void CipherKeyExtended(unsigned char cipherKey[][4] , unsigned char cipherKeySum[][44]);
//加密
void Encrypt(unsigned char inputText[][4],unsigned char cipherKeySum[][44]);
//解密
void Decrypt(unsigned char inputText[][4],unsigned char cipherKeySum[][44]);
//对4*4矩阵进行打印
void printMatrix(unsigned char matrix[][4]);void printMatrix(unsigned char matrix[][4])
{for(int i=0;i<4;i++){for(int j=0;j<4;j++){printf("%.2x ",matrix[i][j]);}printf("\n");}
}void SBoxFunc(unsigned char inputText[][4], unsigned char inputTextEncrypt[][4])
{unsigned int row=0,column=0; for(int i=0;i<4;i++){for(int j=0;j<4;j++){row = (inputText[i][j] & 0xF0) >> 4;column = inputText[i][j]&0x0F;inputTextEncrypt[i][j] = SBox[row][column];}}
}void ReSBoxFunc(unsigned char inputText[][4],unsigned char inputTextEncrypt[][4])
{unsigned int row=0,column=0; for(int i=0;i<4;i++){for(int j=0;j<4;j++){row = (inputText[i][j] & 0xF0) >> 4;column = inputText[i][j]&0x0F;inputTextEncrypt[i][j] = ReSBox[row][column];}}
}void ShiftRows(unsigned char inputTextEncrypt [][4])
{unsigned char temp = 0;for(int i=1;i<4;i++){for(int j=0;j<i;j++){temp = inputTextEncrypt[i][0];inputTextEncrypt[i][0] = inputTextEncrypt[i][1];inputTextEncrypt[i][1] = inputTextEncrypt[i][2];inputTextEncrypt[i][2] = inputTextEncrypt[i][3];inputTextEncrypt[i][3] = temp;}}
}void ReShiftRows(unsigned char inputTextEncrypt [][4])
{unsigned char temp = 0;for(int i=1;i<4;i++){for(int j=0;j<i;j++){temp = inputTextEncrypt[i][3];inputTextEncrypt[i][3] = inputTextEncrypt[i][2];inputTextEncrypt[i][2] = inputTextEncrypt[i][1];inputTextEncrypt[i][1] = inputTextEncrypt[i][0];inputTextEncrypt[i][0] = temp;}}
}unsigned char GFMul01(unsigned char num)
{return num;
}unsigned char GFMul02(unsigned char num)
{unsigned char temp = num>>7&0xFF;if(temp==0x00)return num<<1&0xFF;else if(temp==0x01)return (num<<1&0xFF)^0x1B;
}unsigned char GFMul03(unsigned char num)
{return GFMul01(num)^GFMul02(num);
}unsigned char GFMulAll(unsigned char num1,unsigned char num2)
{if(num2==0x01)return GFMul01(num1);else if(num2==0x02)return GFMul02(num1);else if(num2==0x03)return GFMul03(num1);
}void ColumnMix(unsigned char inputTextEncrypt [][4],unsigned char inputTextColumnMix [][4])
{	for(int j=0;j<4;j++){for(int i=0;i<4;i++){inputTextColumnMix[i][j] = GFMulAll(inputTextEncrypt[0][j],GFMatrix[i][0])^GFMulAll(inputTextEncrypt[1][j],GFMatrix[i][1])^GFMulAll(inputTextEncrypt[2][j],GFMatrix[i][2])^GFMulAll(inputTextEncrypt[3][j],GFMatrix[i][3]);}}
}unsigned char GFMul04(unsigned char num)
{unsigned char temp=num;for(int i=0;i<2;i++){temp = GFMul02(temp);}return temp;
}unsigned char GFMul08(unsigned char num)
{unsigned char temp=num;for(int i=0;i<3;i++){temp = GFMul02(temp);}return temp;
}unsigned char GFMul09(unsigned char num)
{return GFMul08(num)^GFMul01(num);
}unsigned char GFMul0B(unsigned char num)
{return GFMul08(num)^GFMul02(num)^GFMul01(num);
}unsigned char GFMul0D(unsigned char num)
{return GFMul08(num)^GFMul04(num)^GFMul01(num);
}unsigned char GFMul0E(unsigned char num)
{return GFMul08(num)^GFMul04(num)^GFMul02(num);
}unsigned char ReGFMulAll(unsigned char num1,unsigned char num2)
{if(num2==0x09)return GFMul09(num1);else if(num2==0x0B)return GFMul0B(num1);else if(num2==0x0D)return GFMul0D(num1);else if(num2==0x0E)return GFMul0E(num1);
}void ReColumnMix(unsigned char inputTextColumnMix [][4],unsigned char inputTextEncrypt [][4])
{for(int j=0;j<4;j++){for(int i=0;i<4;i++){inputTextEncrypt[i][j] = ReGFMulAll(inputTextColumnMix[0][j],ReGFMatrix[i][0])^ReGFMulAll(inputTextColumnMix[1][j],ReGFMatrix[i][1])^ReGFMulAll(inputTextColumnMix[2][j],ReGFMatrix[i][2])^ReGFMulAll(inputTextColumnMix[3][j],ReGFMatrix[i][3]);}}
}void RoundKeyXOR(unsigned char inputTextColumnMix [][4],unsigned char RoundKey [][4],unsigned char inputText[][4])
{for(int i=0;i<4;i++){for(int j=0;j<4;j++){inputText[i][j] = inputTextColumnMix[i][j]^RoundKey[i][j];}}
}void CipherKeyExtended(unsigned char cipherKey[][4] , unsigned char cipherKeySum[][44])
{for(int i=0;i<4;i++){for(int j=0;j<4;j++){cipherKeySum[i][j] = cipherKey[i][j];}}unsigned char tempColumnLast[4] = {0};for(int j=4;j<44;j++){if(j%4!=0){for(int i=0;i<4;i++){cipherKeySum[i][j] = cipherKeySum[i][j-4]^cipherKeySum[i][j-1];}}else{for(int i=0;i<4;i++){tempColumnLast[i] = cipherKeySum[i][j-1];}unsigned char temp = tempColumnLast[0];for(int k=0;k<3;k++){tempColumnLast[k] = tempColumnLast[k+1];}tempColumnLast[3] = temp;for(int k=0;k<4;k++){tempColumnLast[k] = SBox[(tempColumnLast[k]&0xF0)>>4][tempColumnLast[k]&0x0F];}tempColumnLast[0] = tempColumnLast[0]^R[j/4-1];for(int i=0;i<4;i++){cipherKeySum[i][j] = cipherKeySum[i][j-4]^tempColumnLast[i];}}}
}void Encrypt(unsigned char inputText[][4],unsigned char cipherKeySum[][44])
{unsigned char inputTextEncrypt[4][4] = {0};unsigned char inputTextColumnMix[4][4] = {0};unsigned char cipherKey[4][4] = {0};for(int i=0;i<4;i++){for(int j=0;j<4;j++){cipherKey[i][j] = cipherKeySum[i][j];}}RoundKeyXOR(inputText,cipherKey,inputText);for(int i=1;i<=9;i++){for(int m=0;m<4;m++){for(int n=0;n<4;n++){cipherKey[m][n] = cipherKeySum[m][4*i+n];}}SBoxFunc(inputText,inputTextEncrypt);ShiftRows(inputTextEncrypt);ColumnMix(inputTextEncrypt,inputTextColumnMix);RoundKeyXOR(inputTextColumnMix,cipherKey,inputText);}for(int i=0;i<4;i++){for(int j=0;j<4;j++){cipherKey[i][j] = cipherKeySum[i][40+j];}}SBoxFunc(inputText,inputTextEncrypt);ShiftRows(inputTextEncrypt);RoundKeyXOR(inputTextEncrypt,cipherKey,inputText);
}void Decrypt(unsigned char inputText[][4],unsigned char cipherKeySum[][44])
{unsigned char reInputTextEncrypt[4][4] = {0};unsigned char reInputTextRoundKeyXOR[4][4] = {0};unsigned char cipherKey[4][4] = {0};for(int i=0;i<4;i++){for(int j=0;j<4;j++){cipherKey[i][j] = cipherKeySum[i][40+j];}}RoundKeyXOR(inputText,cipherKey,inputText);for(int m=1;m<=9;m++){for(int i=0;i<4;i++){for(int j=0;j<4;j++){cipherKey[i][j] = cipherKeySum[i][40-4*m+j];}}ReShiftRows(inputText);ReSBoxFunc(inputText,reInputTextEncrypt);RoundKeyXOR(reInputTextEncrypt,cipherKey,reInputTextRoundKeyXOR);ReColumnMix(reInputTextRoundKeyXOR,inputText);}for(int i=0;i<4;i++){for(int j=0;j<4;j++){cipherKey[i][j] = cipherKeySum[i][j];}}ReSBoxFunc(inputText,reInputTextEncrypt);ReShiftRows(reInputTextEncrypt);RoundKeyXOR(reInputTextEncrypt,cipherKey,inputText);
}int main()
{unsigned char inputText1[4][4]={{0x42,0x6c,0x20,0x74},{0x6f,0x6f,0x61,0x68},{0x62,0x6f,0x74,0x69},{0x20,0x6b,0x20,0x73}};							unsigned char inputText2[4][4]={{0x1e,0xca,0xd6,0xce},{0x03,0xf8,0x98,0xfa},{0x40,0x7e,0x93,0x4d},{0xd2,0xc8,0x82,0xd1}};unsigned char cipherKey[4][4] = {{0x3c,0x57,0x90,0xac},{0xa1,0xf0,0x2c,0xc1},{0x0b,0x19,0x13,0x07},{0x21,0x16,0x80,0xbd}};unsigned char cipherKeySum[4][44] = {0};CipherKeyExtended(cipherKey,cipherKeySum);printf("***********AES加密解密运算***********\n要进行加密的明文为：\n");printMatrix(inputText1);printf("\n要解密的密文为：\n");	printMatrix(inputText2);printf("\n密钥扩展为：\n");for(int i=0;i<4;i++){for(int j=0;j<44;j++){printf("%.2x ",cipherKeySum[i][j]);}printf("\n");}printf("\n===============================================================================================\n\n");Encrypt(inputText1,cipherKeySum);Decrypt(inputText2,cipherKeySum);printf("加密后的结果为：\n");printMatrix(inputText1);printf("\n解密后的结果为：\n");printMatrix(inputText2);return 0;
}

运行结果如下所示：

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