美团 CTF 2021 matrix

题目下载: matrix.exe

整体上来说就是 AES 一轮运算部分函数的魔改

输入数据转换成 4 x 4 矩阵，记做 Input

main 函数有 3 处异常

异常依次发生:

EXCEPTION_BREAKPOINT
EXCEPTION_ILLEGAL_INSTRUCTION
EXCEPTION_ACCESS_VIOLATION

每次异常处理都会对输入的数据进行变换,

行混淆

每次异常处理对应的一个特定的变换，外加一个 AES 行混淆

EXCEPTION_BREAKPOINT 异常, 对输入矩阵进行 密钥加 运算

对输入矩阵的每个元素异或 0x6E
对输入矩阵再进行行混淆

EXCEPTION_ILLEGAL_INSTRUCTION

对输入矩阵进行矩阵乘法运算，模 251

M =                               0xe, 0xb, 0xd, 0x9,
                                  0x9, 0xe, 0xb, 0xd,
                                  0xd, 0x9, 0xe, 0xb,
                                  0xb, 0xd, 0x9, 0xe

Input * M % 251

最后进行行混淆

求逆脚本, tt 是输入

from Crypto.Util.number import *


def fun(t):
    ans=[[0 for i in range(4)] for j in range(4)]
    for i in range(4):
        t = [tt[_][i] for _ in range(4)]
        TT = matrix(Zmod(251), t).T

        ansi = inv_mt*TT
        for j in range(4):
            ans[j][i] = ansi[j][0]
    return ans

mt = [
        [14, 11, 13,  9],
        [ 9, 14, 11, 13],
        [13,  9, 14, 11],
        [11, 13,  9, 14]
        ]

MT = Matrix(Zmod(251), mt)
inv_mt = MT.inverse()

tt = [[0x7e,0xd4,0x4a,0x2d],
[0x26,0xc3,0x52,0x9a],
[0x4c,0xa1,0x2b,0x7c],
[0xe5,0x59,0x00,0xfe]]

ans = fun(tt)
print(ans)

EXCEPTION_ACCESS_VIOLATION, 对输入矩阵进行 AES 列混合 并 行混淆

逆运算就是 AES 逆列混合运算

main 函数中的变换

矩阵内元素循环左移

矩阵内每个元素左移动

int rol(int a[4][4] ){
    for (int i = 0 ; i < 4; i++) {
        a[i][0] = __ROL1__(a[i][0], i);
        a[i][1] = __ROL1__(a[i][1], i);
        a[i][2] = __ROL1__(a[i][2], i);
        a[i][3] = __ROL1__(a[i][3], i);
    }
}

逆运算

int ror(int a[4][4] ){
    for (int i = 0 ; i < 4; i++) {
        a[i][0] = __ROR1__(a[i][0], i);
        a[i][1] = __ROR1__(a[i][1], i);
        a[i][2] = __ROR1__(a[i][2], i);
        a[i][3] = __ROR1__(a[i][3], i);
    }
}

AES S 盒置换

逆运算用反S盒即可

XOR 密钥加运算

矩阵中每个元素异或下面这个矩阵对应位置元素即可

1	`0x61, 0x64, 0x6D, 0x69, 0x6E, 0x69, 0x73, 0x74, 0x72, 0x61, 0x74, 0x6F, 0x72, 0x78, 0x5F, 0x78`

整体加密流程

注意异常处理里面的每一种变换后都有一个行混淆

//    1. 字节内移位 rol ，逆运算 ror
//
//    2. 轮密钥加密 xor 0x6E
//
//    3. shift 行混淆
//
//    4. aes S盒加密置换
//
//    5. 矩阵乘法
//
//    6. shift
//
//    7. xor密钥运算 
//
//    8. 列混合
//
//    9. shift

最后输出反推输入即可，注意每一种逆运算。

完整代码

#include <stdio.h>
#include <string.h>
#include <cctype>
#include "ida.h"

#include <stdlib.h>




/**
 * S盒
 */
static 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
 */
static const int S2[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 };
static const int S3[] = { 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
 */
static int getLeft4Bit(int num) {
    int left = num & 0x000000f0;
    return left >> 4;
}

/**
 * 获取整形数据的低8位的右4个位
 */
static int getRight4Bit(int num) {
    return num & 0x0000000f;
}
/**
 * 根据索引，从S盒中获得元素
 */
static int getNumFromSBox(int index) {
    int row = getLeft4Bit(index);
    int col = getRight4Bit(index);
    return S[row][col];
}

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

/**
 * 把16个字符转变成4X4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。
 */
static void convertToIntArray(char *str, int pa[4][4]) {
    int k = 0;
    int i,j;
    for(i = 0; i < 4; i++)
        for(j = 0; j < 4; j++) {
            pa[j][i] = getIntFromChar(str[k]);
            k++;
        }
}

/**
 * 打印4X4的数组
 */
static void printArray(int a[4][4]) {
    int i,j;
    for(i = 0; i < 4; i++){
        for(j = 0; j < 4; j++)
            printf("%x ",  a[i][j]);
        printf("\n");
    }
    printf("\n");
}

/**
 * 打印字符串的ASSCI，
 * 以十六进制显示。
 */
static void printASSCI(char *str, int len) {
    int i;
    for(i = 0; i < len; i++)
        printf("0x%x ", getIntFromChar(str[i]));
    printf("\n");
}

/**
 * 把连续的4个字符合并成一个4字节的整型
 */
static int getWordFromStr(char *str) {
    int one, two, three, four;
    one = getIntFromChar(str[0]);
    one = one << 24;
    two = getIntFromChar(str[1]);
    two = two << 16;
    three = getIntFromChar(str[2]);
    three = three << 8;
    four = getIntFromChar(str[3]);
    return one | two | three | four;
}

/**
 * 把一个4字节的数的第一、二、三、四个字节取出，
 * 入进一个4个元素的整型数组里面。
 */
static void splitIntToArray(int num, int array[4]) {
    int one, two, three;
    one = num >> 24;
    array[0] = one & 0x000000ff;
    two = num >> 16;
    array[1] = two & 0x000000ff;
    three = num >> 8;
    array[2] = three & 0x000000ff;
    array[3] = num & 0x000000ff;
}

/**
 * 将数组中的元素循环左移step位
 */
static void leftLoop4int(int array[4], int step) {
    int temp[4];
    int i;
    int index;
    for(i = 0; i < 4; i++)
        temp[i] = array[i];

    index = step % 4 == 0 ? 0 : step % 4;
    for(i = 0; i < 4; i++){
        array[i] = temp[index];
        index++;
        index = index % 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
 */
static int mergeArrayToInt(int array[4]) {
    int one = array[0] << 24;
    int two = array[1] << 16;
    int three = array[2] << 8;
    int four = array[3];
    return one | two | three | four;
}

/**
 * 常量轮值表
 */
static const unsigned int Rcon[10] = { 0x01000000, 0x02000000,
                              0x04000000, 0x08000000,
                              0x10000000, 0x20000000,
                              0x40000000, 0x80000000,
                              0x1b000000, 0x36000000 };
/**
 * 密钥扩展中的T函数
 */
static int T(int num, int round) {
    int numArray[4];
    int i;
    int result;
    splitIntToArray(num, numArray);
    leftLoop4int(numArray, 1);//字循环

    //字节代换
    for(i = 0; i < 4; i++)
        numArray[i] = getNumFromSBox(numArray[i]);

    result = mergeArrayToInt(numArray);
    return result ^ Rcon[round];
}

//密钥对应的扩展数组
static int w[44];
/**
 * 打印W数组
 */
static void printW() {
    int i, j;
    for(i = 0, j = 1; i < 44; i++,j++){
        printf("w[%d] = 0x%x ", i, w[i]);
        if(j % 4 == 0)
            printf("\n");
    }
    printf("\n");
}


/**
 * 扩展密钥，结果是把w[44]中的每个元素初始化
 */
static void extendKey(char *key) {
    int i,j;
    for(i = 0; i < 4; i++)
        w[i] = getWordFromStr(key + i * 4);

    for(i = 4, j = 0; i < 44; i++) {
        if( i % 4 == 0) {
            w[i] = w[i - 4] ^ T(w[i - 1], j);
            j++;
        }else {
            w[i] = w[i - 4] ^ w[i - 1];
        }
    }

}

/**
 * 轮密钥加
 */
static void addRoundKey(int array[4][4], int round) {
    int warray[4];
    int i,j;
    for(i = 0; i < 4; i++) {

        splitIntToArray(w[ round * 4 + i], warray);

        for(j = 0; j < 4; j++) {
            array[j][i] = array[j][i] ^ warray[j];
        }
    }
}

/**
 * 字节代换
 */
static void subBytes(int array[4][4]){
    int i,j;
    for(i = 0; i < 4; i++)
        for(j = 0; j < 4; j++)
            array[i][j] = getNumFromSBox(array[i][j]);
}

/**
 * 行移位
 */
static void shiftRows(int array[4][4]) {
    int rowTwo[4], rowThree[4], rowFour[4];
    int i;
    for(i = 0; i < 4; i++) {
        rowTwo[i] = array[1][i];
        rowThree[i] = array[2][i];
        rowFour[i] = array[3][i];
    }

    leftLoop4int(rowTwo, 1);
    leftLoop4int(rowThree, 2);
    leftLoop4int(rowFour, 3);

    for(i = 0; i < 4; i++) {
        array[1][i] = rowTwo[i];
        array[2][i] = rowThree[i];
        array[3][i] = rowFour[i];
    }
}

/**
 * 列混合要用到的矩阵
 */
static const int colM[4][4] = { 2, 3, 1, 1,
                                1, 2, 3, 1,
                                1, 1, 2, 3,
                                3, 1, 1, 2 };

static int GFMul2(int s) {
    int result = s << 1;
    int a7 = result & 0x00000100;

    if(a7 != 0) {
        result = result & 0x000000ff;
        result = result ^ 0x1b;
    }

    return result;
}

static int GFMul3(int s) {
    return GFMul2(s) ^ s;
}

static int GFMul4(int s) {
    return GFMul2(GFMul2(s));
}

static int GFMul8(int s) {
    return GFMul2(GFMul4(s));
}

static int GFMul9(int s) {
    return GFMul8(s) ^ s;
}

static int GFMul11(int s) {
    return GFMul9(s) ^ GFMul2(s);
}

static int GFMul12(int s) {
    return GFMul8(s) ^ GFMul4(s);
}

static int GFMul13(int s) {
    return GFMul12(s) ^ s;
}

static int GFMul14(int s) {
    return GFMul12(s) ^ GFMul2(s);
}

/**
 * GF上的二元运算
 */
static int GFMul(int n, int s) {
    int result;

    if(n == 1)
        result = s;
    else if(n == 2)
        result = GFMul2(s);
    else if(n == 3)
        result = GFMul3(s);
    else if(n == 0x9)
        result = GFMul9(s);
    else if(n == 0xb)//11
        result = GFMul11(s);
    else if(n == 0xd)//13
        result = GFMul13(s);
    else if(n == 0xe)//14
        result = GFMul14(s);

    return result;
}
/**
 * 列混合
 */
static void mixColumns(int array[4][4]) {

    int tempArray[4][4];
    int i,j;
    for(i = 0; i < 4; i++)
        for(j = 0; j < 4; j++)
            tempArray[i][j] = array[i][j];

    for(i = 0; i < 4; i++)
        for(j = 0; j < 4; j++){
            array[i][j] = GFMul(colM[i][0],tempArray[0][j]) ^ GFMul(colM[i][1],tempArray[1][j])
                          ^ GFMul(colM[i][2],tempArray[2][j]) ^ GFMul(colM[i][3], tempArray[3][j]);
        }
}
/**
 * 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];
}
/**
 * 检查密钥长度
 */
static int checkKeyLen(int len) {
    if(len == 16)
        return 1;
    else
        return 0;
}


/**
 * 根据索引从逆S盒中获取值
 */
static int getNumFromS1Box(int index) {
    int row = getLeft4Bit(index);
    int col = getRight4Bit(index);
    return S2[row][col];
}
/**
 * 逆字节变换
 */
static void deSubBytes(int array[4][4]) {
    int i,j;
    for(i = 0; i < 4; i++)
        for(j = 0; j < 4; j++)
            array[i][j] = getNumFromS1Box(array[i][j]);
}
/**
 * 把4个元素的数组循环右移step位
 */
static void rightLoop4int(int array[4], int step) {
    int temp[4];
    int i;
    int index;
    for(i = 0; i < 4; i++)
        temp[i] = array[i];

    index = step % 4 == 0 ? 0 : step % 4;
    index = 3 - index;
    for(i = 3; i >= 0; i--) {
        array[i] = temp[index];
        index--;
        index = index == -1 ? 3 : index;
    }
}

/**
 * 逆行移位
 */
static void deShiftRows(int array[4][4]) {
    int rowTwo[4], rowThree[4], rowFour[4];
    int i;
    for(i = 0; i < 4; i++) {
        rowTwo[i] = array[1][i];
        rowThree[i] = array[2][i];
        rowFour[i] = array[3][i];
    }

    rightLoop4int(rowTwo, 1);
    rightLoop4int(rowThree, 2);
    rightLoop4int(rowFour, 3);

    for(i = 0; i < 4; i++) {
        array[1][i] = rowTwo[i];
        array[2][i] = rowThree[i];
        array[3][i] = rowFour[i];
    }
}
/**
 * 逆列混合用到的矩阵
 */
static 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
 */
static void deMixColumns(int array[4][4]) {
    int tempArray[4][4];
    int i,j;
    for(i = 0; i < 4; i++)
        for(j = 0; j < 4; j++)
            tempArray[i][j] = array[i][j];

    for(i = 0; i < 4; i++)
        for(j = 0; j < 4; j++){
            array[i][j] = GFMul(deColM[i][0],tempArray[0][j]) ^ GFMul(deColM[i][1],tempArray[1][j])
                          ^ GFMul(deColM[i][2],tempArray[2][j]) ^ GFMul(deColM[i][3], tempArray[3][j]);
        }
}

/**
 * 把两个4X4数组进行异或
 */
static void addRoundTowArray(int aArray[4][4],int bArray[4][4]) {
    int i,j;
    for(i = 0; i < 4; i++)
        for(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4X4数组，
 * 用于进行逆列混合
 */
static void getArrayFrom4W(int i, int array[4][4]) {
    int index,j;
    int colOne[4], colTwo[4], colThree[4], colFour[4];
    index = i * 4;
    splitIntToArray(w[index], colOne);
    splitIntToArray(w[index + 1], colTwo);
    splitIntToArray(w[index + 2], colThree);
    splitIntToArray(w[index + 3], colFour);

    for(j = 0; j < 4; j++) {
        array[j][0] = colOne[j];
        array[j][1] = colTwo[j];
        array[j][2] = colThree[j];
        array[j][3] = colFour[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,k;
    keylen = strlen(key);
    if(clen == 0 || clen % 16 != 0) {
        printf("密文字符长度必须为16的倍数！现在的长度为%d\n",clen);
        exit(0);
    }

    if(!checkKeyLen(keylen)) {
        printf("密钥字符长度错误！长度必须为16、24和32。当前长度为%d\n",keylen);
        exit(0);
    }

    extendKey(key);//扩展密钥

    for(k = 0; k < clen; k += 16) {
        int i;
        int wArray[4][4];

        convertToIntArray(c + k, cArray);





        addRoundKey(cArray, 10);

        for(i = 9; i >= 1; i--) {
            deSubBytes(cArray);

            deShiftRows(cArray);

            deMixColumns(cArray);
            getArrayFrom4W(i, wArray);
            deMixColumns(wArray);

            addRoundTowArray(cArray, wArray);
        }

        deSubBytes(cArray);

        deShiftRows(cArray);

        addRoundKey(cArray, 0);

        convertArrayToStr(cArray, c + k);

    }
}


int rol(int a[4][4] ){
    for (int i = 0 ; i < 4; i++) {
        a[i][0] = __ROL1__(a[i][0], i);
        a[i][1] = __ROL1__(a[i][1], i);
        a[i][2] = __ROL1__(a[i][2], i);
        a[i][3] = __ROL1__(a[i][3], i);
    }
}

int ror(int a[4][4] ){
    for (int i = 0 ; i < 4; i++) {
        a[i][0] = __ROR1__(a[i][0], i);
        a[i][1] = __ROR1__(a[i][1], i);
        a[i][2] = __ROR1__(a[i][2], i);
        a[i][3] = __ROR1__(a[i][3], i);
    }
}


int main(int argc, char const *argv[])
{
    int xor2[16] = {
            0x61, 0x64, 0x6D, 0x69, 0x6E, 0x69, 0x73, 0x74, 0x72, 0x61, 0x74, 0x6F, 0x72, 0x78, 0x5F, 0x78
    };
    int target[4][4] = {
            0xF4, 0xA5, 0x15, 0xD1, 0xF7, 0xFD, 0x37, 0xA3, 0x01, 0x95, 0x03, 0x2A, 0x10, 0x2A, 0x0B, 0xEF
    };

//    1. 字节内移位
//
//    2. 轮密钥加密
//
//    3. shift
//
//    4. aes S盒加密置换
//
//    5. 矩阵乘法
//
//    6. shift
//
//    7. xor密钥运算
//
//    8. 列混合
//
//    9. shift

    printf("ori:\n");
    printArray(target);

    deShiftRows(target);

    printf("9. shift_in:\n");
    printArray(target);


    deMixColumns(target);


    printf("8. 列混合 in:\n");
    printArray(target);


    for(int i = 0; i < 4; i++) {
        for (int j = 0; j < 4; ++j) {
         //   printf("%x %x\n",xor2[i * 4 + j],  target[i * 4][j]);
            target[i][j] ^= xor2[i * 4 + j];
        }
    }

    printf(" 7. xor密钥运算 in:\n");
    printArray(target);

    deShiftRows(target);
    printf(" 6. shift in:\n");
    printArray(target);



    // 矩阵逆
    int target2[4][4] = {0xb5, 0xbd, 0x8, 0xc5,
                         0x74, 0x3e, 0x5f, 0x4b,
                         0xdb, 0xc2, 0x1d, 0x2,
                         0x19, 0x42, 0xa0, 0xf6};

    printf("5. 矩阵乘法 in:\n");
    printArray(target2);

    for(int i = 0; i < 4; i++) {
        for (int j = 0; j < 4; ++j) {
            target2[i][j] = S3[target2[i][j]];
        }
    }
    printf("4. aes S盒加密置换 in:\n");
    printArray(target2);

    deShiftRows(target2);
    printf(" 3. shift in:\n");
    printArray(target2);
    for(int i = 0; i < 4; i++) {
        for (int j = 0; j < 4; ++j) {
            target2[i][j] ^= 0x6e;
        }
    }
    printf("2. 轮密钥加密 in:\n");
    printArray(target2);


    ror(target2);
    printf("1.in:\n");
    printArray(target2);
}

CTF

Reverse AES

本博客所有文章除特别声明外，均采用 CC BY-SA 4.0 协议，转载请注明出处！

美团CTF: 100mazes Previous

CISCN gift Next

美团CTF: matrix

美团 CTF 2021 matrix

main 函数有 3 处异常

main 函数中的变换

整体加密流程