AES是目前最常用最可靠的一种加解密方式
其过程的精妙性不言而喻
但是伴随着安全性而来的就是编程的复杂性
我翻遍了各种网站，惊奇地发现这种广为（信息学）人知的算法代码竟然是少之又少
然而在我根据大大的指导复刻这个经典算法的时候
难过地发现加解密并不互逆（极度离谱）
按理说在解密过程中，对轮密钥要进行一次逆列混合后再进行密钥加
但是逆列混合后的轮密钥呈现出一种混沌状态，无法正确解密
因此我对于解密过程做了小小的调整
保证加解密完全100%对称
（但是这样就不符合AES的最初设计思路了，可恶）
以下代码可以完美实现加解密，但是内部逻辑和传统AES有些许不同：
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;
const int MAX_NUM = 1000;
char M[MAX_NUM], C[MAX_NUM], K[MAX_NUM];
bool flag = 0;
//S盒
const int S[16][16] = { 0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 };
//逆S盒
const int _S[16][16] = { 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 };
//获取整形数据的低8位的左4个位
int getLeft4Bit(int num) {
int left = num & 240;
return left >> 4;
}
//获取整形数据的低8位的右4个位
int getRight4Bit(int num) {
return num & 15;
}
void printArray(int a[4][4]) {
for (int i = 0;i < 4;++i)
for (int j = 0;j < 4;++j) {
int x, y;
x = getLeft4Bit(a[j][i]);
y = getRight4Bit(a[j][i]);
if (x > 9)
cout << (char)(x - 10 + 'a');
else cout << x;
if (y > 9)
cout << (char)(y - 10 + 'a');
else cout << y;
}
cout << endl;
}
//根据索引，从S盒中获得元素
int getNumFromSBox(int index) {
int x = getLeft4Bit(index);
int y = getRight4Bit(index);
return S[x][y];
}
//把一个字符转变成整型(8bit)
int getIntFromChar(char c) {
int result = (int)c;
return result & 255;
}
//把16个字符转变成4*4的数组
//该矩阵中字节的排列顺序为从上到下
//从左到右依次排列
void convertToIntArray(char* str, int a[4][4]) {
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; ++j) {
a[j][i] = getIntFromChar(str[i*4+j]);
}
}
//把16个数字转换成4*4的数组
//该矩阵中的排列顺序为从上到下
//从左到右依次排列
void convertToIntArray_2(char* str, int a[4][4]) {
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; ++j) {
int x, y;
if (str[2 * (i * 4 + j)] >= 'a' && str[2 * (i * 4 + j)] <= 'f')
x = str[2 * (i * 4 + j)] - 'a' + 10;
else x = str[2 * (i * 4 + j)] - '0';
if (str[2 * (i * 4 + j) + 1] >= 'a' && str[2 * (i * 4 + j) + 1] <= 'f')
y = str[2 * (i * 4 + j) + 1] - 'a' + 10;
else y = str[2 * (i * 4 + j) + 1] - '0';
a[j][i] = x * 16 + y;
}
}
//把连续的4个字符合并成一个4字节的整型
int getWordFromStr(char* str) {
int a, b, c, d;
a = getIntFromChar(str[0]);
b = getIntFromChar(str[1]);
c = getIntFromChar(str[2]);
d = getIntFromChar(str[3]);
return (a << 24) + (b << 16) + (c << 8) + d;
}
//把一个4字节数的第一、二、三、四个字节取出，
//放入一个4元素整型数组里
void splitIntToArray(int num, int a[4]) {
a[0] = (num >> 24) & 255;
a[1] = (num >> 16) & 255;
a[2] = (num >> 8) & 255;
a[3] = num & 255;
}
//将数组中的元素循环左移step位
void leftLoop4int(int a[4], int step) {
step %= 4;
if (!step) return;
int index = 4 - step;
int tmp[4];
for (int i = 0; i < 4; ++i)
tmp[i] = a[i];
for (int i = 0;i < 4;++i) {
a[index] = tmp[i];
index = (index + 1) % 4;
}
}
//把数组中的第一、二、三和四元素分别作为
//4字节整型的第一、二、三和四字节，合并成一个4字节整型
int mergeArrayToInt(int a[4]) {
return (a[0] << 24) + (a[1] << 16) + (a[2] << 8) + a[3];
}
//常量轮值表
static const int Rcon[10] = { 0x01000000, 0x02000000,
0x04000000, 0x08000000,
0x10000000, 0x20000000,
0x40000000, 0x80000000,
0x1b000000, 0x36000000 };
//密钥扩展中的T函数
int T(int num, int round) {
int numArray[4];
int ans;
splitIntToArray(num, numArray); //先split方便之后的S盒替换
leftLoop4int(numArray, 1);//字循环
//字节代换
for (int i = 0; i < 4; ++i)
numArray[i] = getNumFromSBox(numArray[i]);
ans = mergeArrayToInt(numArray);
return ans ^ Rcon[round];
}
//密钥对应的扩展数组
int w[44];
//扩展密钥
void extendKey(char* key) {
for (int i = 0; i < 4; ++i)
w[i] = getWordFromStr(key + i * 4);
for (int i = 4, j = 0; i < 44; ++i) {
if (i % 4 == 0) {
w[i] = w[i - 4] ^ T(w[i - 1], j);
++j;//下一轮
}
else {
w[i] = w[i - 4] ^ w[i - 1];
}
}
}
//密钥加
void addRoundKey(int a[4][4], int round) {
int _w[4];
for (int i = 0; i < 4; ++i) {
splitIntToArray(w[round * 4 + i], _w);
for (int j = 0; j < 4; ++j) {
a[j][i] = a[j][i] ^ _w[j];
}
}
}
//字节代换
void subBytes(int a[4][4]) {
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; ++j)
a[i][j] = getNumFromSBox(a[i][j]);
}
//行移位
void shiftRows(int a[4][4]) {
int row1[4], row2[4], row3[4];
for (int i = 0; i < 4; ++i) {
row1[i] = a[1][i];
row2[i] = a[2][i];
row3[i] = a[3][i];
}
leftLoop4int(row1, 1);
leftLoop4int(row2, 2);
leftLoop4int(row3, 3);
for (int i = 0; i < 4; ++i) {
a[1][i] = row1[i];
a[2][i] = row2[i];
a[3][i] = row3[i];
}
}
//列混合要用到的矩阵
const int colM[4][4] = { 2, 3, 1, 1,
1, 2, 3, 1,
1, 1, 2, 3,
3, 1, 1, 2 };
//xtimes
int xtimes(int x) {
int ans = x << 1;
int o = ans & 0x00000100;
if (o != 0) { //有进位
ans = ans & 255;
ans = ans ^ 0x1b;
}
return ans;
}
//GF上的二元运算 n*x
int GFMul(int n, int x) {
if (n == 0) return 0;
int ans = 1;
while (n) {
if (n & 1) {
ans = ans ^ x;
}
n >>= 1;
x = xtimes(x);
}
return ans;
}
//列混合
void mixColumns(int a[4][4]) {
int tmp[4][4];
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; ++j)
tmp[i][j] = a[i][j];
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; ++j) {
a[i][j] = GFMul(colM[i][0], tmp[0][j]) ^ GFMul(colM[i][1], tmp[1][j])
^ GFMul(colM[i][2], tmp[2][j]) ^ GFMul(colM[i][3], tmp[3][j]);
}
}
//把4*4数组转回字符串
void convertArrayToStr(int a[4][4], char* str) {
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; ++j)
*str++ = (char)a[j][i];
}
/*
* 参数 m: 明文的字符串数组
* 参数 mlen: 明文的长度
* 参数 key: 密钥的字符串数组
*/
void Aes(char* m, int mlen, char* key) {
int keylen = strlen(key);
int mArray[4][4];
if (mlen == 0 || mlen % 16 != 0) {
cout << "明文字符长度必须为16的倍数!\n";
return;
}
if (keylen != 16) {
cout << "密钥字符长度错误! 长度必须为16, 当前长度" << keylen << endl;
return;
}
extendKey(key);//扩展密钥
for (int k = 0; k < mlen; k += 16) {
//加密是对字符直接进行加密
convertToIntArray(m + k, mArray);
cout << "明文:\n";
printArray(mArray);
addRoundKey(mArray, 0);//一开始的轮密钥加
for (int i = 1; i < 10; ++i) {
subBytes(mArray);//字节代换
shiftRows(mArray);//行移位
mixColumns(mArray);//列混合
addRoundKey(mArray, i);
}
subBytes(mArray);//字节代换
shiftRows(mArray);//行移位
addRoundKey(mArray, 10);
//convertArrayToStr(mArray, m + k);
}
//加密结果直接以数字输出
cout << "密文:\n";
printArray(mArray);
}
//根据索引从逆S盒中获取值
int getNumFrom_SBox(int index) {
int x = getLeft4Bit(index);
int y = getRight4Bit(index);
return _S[x][y];
}
//逆字节变换
void deSubBytes(int a[4][4]) {
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; ++j)
a[i][j] = getNumFrom_SBox(a[i][j]);
}
//把4个元素的数组循环右移step位
void rightLoop4int(int a[4], int step) {
step %= 4;
if (!step) return;
int index = step;
int tmp[4];
for (int i = 0; i < 4; ++i)
tmp[i] = a[i];
for (int i = 0;i < 4;++i) {
a[index] = tmp[i];
index = (index + 1) % 4;
}
}
//逆行移位
void deShiftRows(int a[4][4]) {
int row1[4], row2[4], row3[4];
for (int i = 0; i < 4; ++i) {
row1[i] = a[1][i];
row2[i] = a[2][i];
row3[i] = a[3][i];
}
rightLoop4int(row1, 1);
rightLoop4int(row2, 2);
rightLoop4int(row3, 3);
for (int i = 0; i < 4; ++i) {
a[1][i] = row1[i];
a[2][i] = row2[i];
a[3][i] = row3[i];
}
}
//逆列混合用到的矩阵
const int deColM[4][4] = { 0xe, 0xb, 0xd, 0x9,
0x9, 0xe, 0xb, 0xd,
0xd, 0x9, 0xe, 0xb,
0xb, 0xd, 0x9, 0xe };
//逆列混合
void deMixColumns(int a[4][4]) {
int tmp[4][4];
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; ++j)
tmp[i][j] = a[i][j];
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; ++j) {
a[i][j] = GFMul(deColM[i][0], tmp[0][j]) ^ GFMul(deColM[i][1], tmp[1][j])
^ GFMul(deColM[i][2], tmp[2][j]) ^ GFMul(deColM[i][3], tmp[3][j]);
}
}
//把两个4*4数组进行异或
void addRoundTowArray(int aArray[4][4], int bArray[4][4]) {
for (int i = 0; i < 4; ++i)
for (int j = 0; j < 4; ++j)
aArray[i][j] = aArray[i][j] ^ bArray[i][j];
}
//从4个32位的密钥字中获得4*4数组，
//按照从上到下，从左到右的顺序填充进a中
//用于进行逆列混合
void getArrayFrom4W(int i, int a[4][4]) {
int index;
int col1[4], col2[4], col3[4], col4[4];
index = i * 4;
splitIntToArray(w[index], col1);
splitIntToArray(w[index + 1], col2);
splitIntToArray(w[index + 2], col3);
splitIntToArray(w[index + 3], col4);
for (int j = 0; j < 4; ++j) {
a[j][0] = col1[j];
a[j][1] = col2[j];
a[j][2] = col3[j];
a[j][3] = col4[j];
}
}
/*
* 参数 c: 密文的字符串数组
* 参数 clen: 密文的长度
* 参数 key: 密钥的字符串数组
*/
void deAes(char* c, int clen, char* key) {
int cArray[4][4];
int keylen;
keylen = strlen(key);
if (clen == 0 || clen % 16 != 0) {
cout << "密文字符长度必须为16的倍数!\n";
return;
}
if (keylen != 16) {
cout << "密钥字符长度错误! 长度必须为16, 当前长度为" << keylen << endl;
return;
}
extendKey(key);//扩展密钥
for (int k = 0; k < clen; k += 16 * 2) {
int i;
int wArray[4][4];
//由于加密后得到的值可能超过ASCII的显示范围
//所以解密针对数字进行
convertToIntArray_2(c + k, cArray);
addRoundKey(cArray, 10);
for (i = 9; i >= 1; i--) {
deShiftRows(cArray);
deSubBytes(cArray);
//getArrayFrom4W(i, wArray);
//deMixColumns(wArray);
//addRoundTowArray(cArray, wArray);
addRoundKey(cArray, i);
deMixColumns(cArray);
}
deShiftRows(cArray);
deSubBytes(cArray);
addRoundKey(cArray, 0);
//convertArrayToStr(cArray, c + k);
}
//解密结果以字符串形式输出
cout << "明文:\n";
printArray(cArray);
}
int main() {
int opt;
do {
cout << "\n选择操作: 1->信息加密, 2->信息解密, 3->退出\n";
cin >> opt;
switch (opt) {
case 1:
cout << "\n请输入待加密明文(长度限定为16的倍数):\n";
cin >> M;
cout << "请输入密钥(长度限定为16):\n";
cin >> K;
Aes(M,strlen(M),K);
flag = 1;
break;
case 2:
cout << "\n请输入待解密密文(长度限定为16的倍数):\n";
cin >> C;
cout << "请输入密钥(长度限定为16):\n";
cin >> K;
deAes(C, strlen(C), K);
break;
default:
break;
}
} while (opt != 3);
return 0;
}
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