[C++知识库]AES CBC模式 原理 c++完整代码可运行

现在网上能找到的AES代码九成都是ECB模式的，剩下的一成里又有九成只对十六个一组的数进行了加解密处理，压根没有分组。我在网上扒拉了好久都没有找到CBC模式的完整代码，只有接口函数。

CBC的分组原理就是这个图嘛，但是所有的接口函数都只告诉你，需要用到初始向量IV，不告诉你初始向量IV到底是什么，然后我被某个教程坑的老惨了，它告诉我第一次就是当前分组，我这样写出来的代码就一直出错。我测了一下发现无论我加解密的长度是多少，永远都是第一个分组的解密有问题，而且每回的错误解密结果都一模一样，就开始到处加打印输出，一输出就发现我是真蠢得不清，异或的逻辑是相同为0不同为1啊，它如果异或它本身的话结果永远为0，这也是为什么无论我输入什么，解密结果错误的那一段一直相同了。

目前代码是加密文明、密钥、解密结果全部使用正常字符串，没来得及写字节填充，明文要求是16的倍数，密钥必须是16位，加密结果放在本地文件中，解密时也需要从本地文件里读数据。

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <cstring>

using namespace std;

unsigned char xtime (unsigned char input);
void keyexpansion(unsigned char S_BOX[][16], unsigned char keys[][44]);
void bytesub(unsigned char S_BOX[][16], unsigned char B[][4]);
void shiftrow(unsigned char B[][4]);
void mixcolumn(unsigned char input[][4]);
void invbytesub(unsigned char N_S_BOX[][16], unsigned char B[][4]);
void invshiftrow(unsigned char B[][4]);
void invmixcolum(unsigned char input[][4]);
int encrypt(unsigned char S_BOX[][16]);
int decrypt(unsigned char S_BOX[][16], unsigned char N_S_BOX[][16]);

static int getIntFromChar(char c);
static void convertArrayToStr(int array[4][4], char* str);
void writeStrToFile(char* str, int len, char* fileName);
void xorWithiv(unsigned char iv[4][4], unsigned char B[4][4]);


//把一个字符转变成整型
static int getIntFromChar(char c) {
	int result = (int)c;
	return result & 0x000000ff;
}

//把4X4数组转回字符串
static void convertArrayToStr(int array[4][4], char* str) {
	int i, j;
	for (i = 0; i < 4; i++)
		for (j = 0; j < 4; j++)
			*str++ = (char)array[j][i];
}

//把字符串写进文件
void writeStrToFile(char* str, int len, char* fileName) {
	FILE* fp;
	fp = fopen(fileName, "wb");
	for (int i = 0; i < len; i++)
		putc(str[i], fp);
	fclose(fp);
}

//从文件中读取字符串
int readStrFromFile(char* fileName, char* str) {
	FILE* fp = fopen(fileName, "rb");
	if (fp == NULL) {
		printf("打开文件出错，请确认文件存在当前目录下！\n");
		exit(0);
	}

	int i;
	for (i = 0; i < 1024 && (str[i] = getc(fp)) != EOF; i++);

	if (i >= 1024) {
		printf("解密文件过大！\n");
		exit(0);
	}

	str[i] = '\0';
	fclose(fp);
	return i;
}

//和偏移向量进行异或
void xorWithiv(unsigned char iv[4][4], unsigned char B[4][4]){
    for(int i = 0; i <= 3; i ++){
        for(int j = 0; j <= 3; j ++){
            B[i][j]^= iv[i][j];
        }
    }
} 

//密钥生成
void keyexpansion(unsigned char S_BOX[][16], unsigned char keys[][44]){

    unsigned char Rcon[11] = {0, 1, 2, 4, 8, 16, 32, 64, 128, 27, 54};
    unsigned char past[4];
    register int i, j; 
    
    char str[16];
    int k = 0;

    printf("Please enter the key:\n");
    
    scanf("%s", str);

    for(i = 0; i <= 3; i ++)
        for(j = 0; j <= 3; j ++){
        	keys[j][i] = getIntFromChar(str[k]);
        	k ++;
		}

    for(i = 4; i <= 43; i ++){             //make the other 40 keys
        if(i % 4 == 0){                    //如果能被4整除，特殊处理
            for(j = 1; j <= 4; j ++)      //把前一个密钥移位赋值给数组
                past[j - 1] = keys[j % 4][i -1];

            for(j = 0; j <= 3; j ++){
                if(j == 0)
                    keys[j][i] = S_BOX[past[j] / 16][past[j] % 16] ^ Rcon[i / 4] ^ keys[j][i - 4];
                else
                    keys[j][i] = S_BOX[past[j] / 16][past[j] % 16] ^ keys[j][i - 4];
            }
        }

        else{
			for(j = 0; j <= 3; j ++){
                keys[j][i] = keys[j][i - 4] ^ keys[j][i - 1];
            }
        }
    }
}


//列混淆运算用到的乘2函数
unsigned char xtime (unsigned char input){    // x乘法('02'乘法)

    int temp;
    temp = input << 1;
    
    if(input & 0x80){
        temp ^= 0x1b;
    }

    return temp;

}

//列混淆运算
void mixcolumn(unsigned char input[][4]){  //列混淆

    int i, j;
    unsigned char output[4][4];

    for(j = 0; j <= 3; j++)
        for(i = 0; i <= 3; i++)
            output[i][j] = xtime(input[i%4][j]) //0x02乘法
                           ^ ( input[ ( i + 1 ) % 4][j] ^ xtime( input[ ( i + 1 ) % 4][j] ) ) //0x03乘法
                           ^ input[ ( i + 2 ) % 4][j]  //0x01乘法
                           ^ input[ ( i + 3 ) % 4][j]; //0x01乘法

    for(i = 0; i <= 3; i ++)
        for(j = 0; j <= 3; j ++)
            input[i][j] = output[i][j];

}

//行移位

void shiftrow(unsigned char B[][4]){

    int i, temp;
    temp = B[1][0];

    for(i = 0; i <= 2; i ++)
        B[1][i] = B[1][i + 1];
    B[1][3] = temp;

    for(i = 0; i <= 1; i ++){

        temp = B[2][i];
        B[2][i] = B[2][i + 2];
        B[2][i + 2] = temp;

    }

    temp = B[3][3];
    for(i = 3; i >= 1; i --)
        B[3][i] = B[3][i - 1];
    B[3][0] = temp;

}

//字节变换
void bytesub(unsigned char S_BOX[][16], unsigned char B[][4]){

    register int i, j;
    
    for(i = 0; i <= 3; i ++)
        for(j = 0; j <= 3; j ++)
            B[i][j] = S_BOX[B[i][j] / 16][B[i][j] % 16];

}

//逆行移位
void invshiftrow(unsigned char B[][4]){

    int i, temp;

    temp = B[1][3];

    for(i = 3; i >= 1; i --)
        B[1][i] = B[1][i - 1];
    B[1][0] = temp;

    for(i = 0; i <= 1; i ++){
        temp = B[2][i];
        B[2][i] = B[2][i + 2];
        B[2][i + 2] = temp;
    }

    temp = B[3][0];

    for(i = 0; i <= 2; i ++)
        B[3][i] = B[3][i + 1];
    B[3][3] = temp;

}

//逆列混淆运算

void invmixcolum(unsigned char input[][4]){

    int i, j;
    unsigned char output[4][4];

    for(j = 0; j < 4; j++)
        for(i = 0; i < 4; i++)
            output[i][j] = (xtime(xtime(xtime(input[i % 4][j]))) ^ xtime(xtime(input[i % 4][j])) ^ xtime(input[i % 4][j])) //0x0E乘法
                           ^ (xtime(xtime(xtime(input[ ( i + 1 ) % 4][j]))) ^ xtime(input[ ( i + 1 ) % 4][j]) ^ input[ ( i + 1 ) % 4][j]) //0x0B乘法
                           ^ (xtime(xtime(xtime(input[ ( i + 2 ) % 4][j]))) ^ xtime(xtime(input[ ( i + 2 ) % 4][j])) ^ input[ ( i + 2 ) % 4][j]) //0x0D乘法
                           ^ (xtime(xtime(xtime(input[ ( i + 3 ) % 4][j]))) ^ input[ ( i + 3 ) % 4][j]); //0x09乘法

    for(i = 0; i <= 3; i ++)
        for(j = 0; j <= 3; j ++)
            input[i][j] = output[i][j];

}

//逆字节变换
void invbytesub(unsigned char N_S_BOX[][16], unsigned char B[][4]){

    register int i, j;

    for(i = 0; i <= 3; i ++)
        for(j = 0; j <= 3; j ++)
            B[i][j] = N_S_BOX[B[i][j] / 16][B[i][j] % 16];

}


int encrypt(unsigned char S_BOX[][16]){
 
    unsigned char e, B[4][4], iv[4][4];
    unsigned char keys[4][44];
    int i, j;
    int level;
    
    char str[1024],result[1024]; 
    int cArray[4][4];
    int len, k, l;

    printf("Please enter the plaintext:\n");

//这一段替换掉了原来的直接读入十六位进制数，改为读字符串后转换    
    scanf("%s", str);
    getchar();
    len = strlen(str);
    if(len % 16 != 0){
    	printf("请输入十六的倍数长度\n");
    	return 0;
	}
    
    keyexpansion(S_BOX, keys);
    
//    printf("The ciphertext is：\n");
    
    k = 0;
    
    for(l = 0; l < len; l += 16){
    	
    	k = l;
    	for(i = 0; i <= 3; i ++){
    		for(j = 0; j <= 3; j ++){
    			B[j][i] = getIntFromChar(str[k]);
    			k++;
			}
		}
		if(l == 0){
			for(i = 0; i < 4; i ++){
				for(j = 0; j < 4; j ++){
				//	iv[i][j] = B[i][j];
					iv[i][j] = 0;					
				}
			}

		}
		
		//iv=text; 
		
		xorWithiv(iv, B); //和偏移向量进行异或 

		//轮密钥加 
		for(i = 0; i <= 3; i ++)
        	for(j = 0; j <= 3; j ++){
            	B[i][j] ^= keys[i][j];
        	}
        	
        	
        for(level = 1; level <= 9; level ++){    //1到9轮循环
        	bytesub(S_BOX, B); //字节代换 
        	shiftrow(B);  //行移位 
        	mixcolumn(B);  //列混合 

			//这里似乎又是轮密钥加 
        	for(i = 0; i <= 3; i ++)
        	    for(j = 0; j <= 3; j ++)
        	        B[i][j] ^= keys[i][level * 4 + j];        	                	        
    	}

    	bytesub(S_BOX, B);               //第10轮循环
    	shiftrow(B);
    	
    	for(i = 0; i <= 3; i ++)
        	for(j = 0; j <= 3; j ++){ 
            	B[i][j] ^= keys[i][40 + j];
            	cArray[i][j] = (int)B[i][j];      
        	} 
        	
        convertArrayToStr(cArray, result+l);
	
		//iv=test
		//iv = B;
		for(i = 0; i < 4; i ++){
			for(j = 0; j < 4; j ++){
				iv[i][j] = B[i][j];
			}
		}
  	
	}
	result[len]='\0';
//	printf("%s",result);
	char fileName[64];
	printf("请输入你想要写进的文件名，比如'test.txt':\n");
	if (scanf("%s", fileName) == 1) {
		writeStrToFile(result, len, fileName);
		printf("已经将密文写进%s中了,可以在运行该程序的当前目录中找到它。\n", fileName);
	}

    return 0;
}

int decrypt(unsigned char S_BOX[][16], unsigned char N_S_BOX[][16]){
 
    unsigned char B[4][4], iv[4][4], bef[4][4];
    unsigned char keys[4][44];
    int temp, i, j;
    int level;
    
    char str[1024];
    char result[1024];
    int cArray[4][4];
    int len, l, k;
    
    char fileName[64];
    printf("请输入要解密的文件名，该文件必须和本程序在同一个目录\n");
    if (scanf("%s", fileName) == 1){
    	int clen = readStrFromFile(fileName, str);
	}

    len = strlen(str);
//    printf("len=%d\n",len);
    
    keyexpansion(S_BOX, keys);
    
    printf("The output information as:\n");

	for(l = 0; l < len; l +=16){
    	k = l;
    	for(i = 0;i <=3; i ++){
    		for(j = 0; j <=3; j ++){
    			B[j][i] = getIntFromChar(str[k]);
    			bef[j][i] = B[j][i];
    			k ++;
			}
		}

		if(l == 0){
			for(i = 0; i < 4; i ++){
				for(j = 0; j < 4; j ++){
				//	iv[i][j] = bef[i][j];
					iv[i][j] = 0;
				}
			}
		}

		for(i = 0; i <= 3; i ++)
        	for(j = 0; j <= 3; j ++)
            	B[i][j] ^= keys[i][j + 40];
		
		for(level = 1; level <= 9; level ++){

        	invshiftrow(B);
        	invbytesub(N_S_BOX, B);

        	for(i = 0; i <= 3; i ++)
        	    for(j = 0; j <= 3; j ++)
        	        B[i][j] ^= keys[i][40 - level * 4 + j];

        	invmixcolum(B);
    	}

    	invshiftrow(B);
    	invbytesub(N_S_BOX, B);
    	
    	for(i = 0; i <= 3; i ++)
        	for(j = 0; j <= 3; j ++){
        	      B[i][j] ^= keys[i][j];			           	
			}

		xorWithiv(iv, B);

		//iv=B
		for(i = 0; i < 4; i ++){
			for(j = 0; j < 4; j ++){
				iv[i][j] = bef[i][j];
				cArray[i][j] = (int)B[i][j]; 
		//		cout<<cArray[i][j]<<" ";
			}
		}
	
		convertArrayToStr(cArray, result+l);
					
	}
	result[len]='\0';
			
	printf("%s",result);
 

    return 0;

}

int main()
{

    unsigned char S_BOX[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
    };

    unsigned char N_S_BOX[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
    };

    int choose;

    printf("This is C implementation of AES:\n");//打印标题

loop:

    printf("\nEncryption please enter: 1\n");
    printf("Decryption please input: 2\n");
    printf("Exit please input: 0 \n\n");
    printf("Please enter your choice:");
    
    scanf("%d", &choose);

    switch(choose){

    case 1:
        encrypt(S_BOX);
        goto loop;

    case 2:
        decrypt(S_BOX, N_S_BOX);
        goto loop;

    case 0:
        exit(0);

    default :
        exit(0);

    }

    return 0;

}

//Test number

//Key

//2b 7e 15 16 28 ae d2 a6 ab f7 15 88 09 cf 4f 3c


// 一个中文占两个字符位置 

贴一下我参考的相关链：

AES五种加密模式（CBC、ECB、CTR、OCF、CFB）
https://www.cnblogs.com/starwolf/p/3365834.html

aes相关资料整理及代码C/C++（这我自己写的，里边放着应用密码学书上的aes代码，我就是以这个为基础开始改动增加功能的）
https://blog.csdn.net/mandiheyanyu/article/details/123197186

AES加密算法的详细介绍与实现（文件读取什么的是从这里借鉴的）
https://blog.csdn.net/qq_28205153/article/details/55798628

C++实现AES算法，ECB/CBC模式，PKCS#7填充加解密（我cbc主要看的这个里边的接口函数）
https://www.cnblogs.com/dayq/p/15359184.html

C++ 和 java 使用 AES CBC 128 加解密（救我一命告诉我IV到底是个啥玩意的代码，我居然还是从java部分看的）
https://www.cnblogs.com/diegodu/p/6273611.html