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[原创]2021美团CTF-matrix
发表于: 2021-5-27 02:55 14323

[原创]2021美团CTF-matrix

2021-5-27 02:55
14323

matrix

一:逻辑分析

按照执行顺序进行的分析

1. 检测flag格式, 取出矩阵

检测我们的flag形式,然后再取出我们flag中的32个数据sscanf到另外一个数组中,形成一个matrix(4 x 4矩阵)

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bool v24; // cf
  const char *v25; // eax
  _DWORD *v27; // [esp+Ch] [ebp-28h]
  DWORD input[5]; // [esp+10h] [ebp-24h] BYREF
  __int64 v29; // [esp+24h] [ebp-10h]
  int v30; // [esp+2Ch] [ebp-8h]
 
  v3 = new(0x64u);
  input_data = new(0x10u);
  v27 = (_DWORD *)input_data;
  ptr_to_input_0 = (int **)new(0x10u);
  *(__m128i *)ptr_to_input_0 = _mm_add_epi32(
                                 _mm_slli_epi32((__m128i)xmmword_A40A00, 2u),
                                 _mm_shuffle_epi32(_mm_cvtsi32_si128(input_data), 0));
  printf("Give me your password: ");
  sub_9F1060(&dword_A4087C, v3);
  if ( strlen((const char *)v3) != 42
    || strncmp((const char *)v3, "flag{", 5u)   // 测试数据:
                                                // flag{0123456b-789a-bcde-qwer-0123456789cd}
    || *(_BYTE *)(v3 + 41) != '}'
    || *(_BYTE *)(v3 + 13) != '-'
    || *(_BYTE *)(v3 + 18) != '-'
    || *(_BYTE *)(v3 + 23) != '-'
    || *(_BYTE *)(v3 + 28) != '-' )
  {
    printf("Get out of here!\n");
    exit(0);
  }
  v5 = *(_QWORD *)(v3 + 0x1D);
  v6 = *(_DWORD *)(v3 + 9);
  input[0] = *(_DWORD *)(v3 + 5);
  input[2] = *(_DWORD *)(v3 + 14);
  input[3] = *(_DWORD *)(v3 + 19);
  input[4] = *(_DWORD *)(v3 + 0x18);
  v7 = *(_DWORD *)(v3 + 0x25);
  k = 0;
  input[1] = v6;
  v29 = v5;
  v30 = v7;                                     // copy data(将数据提取出来)
  do
  {
    sscanf((char *)input + k, "%02x", input_data + ((unsigned int)k >> 1));// v28 -> v4
    k += 2;
  }
  while ( k < 32 );

2. 矩阵字节内位移

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_ESI = ptr_to_input_0;                        // 取我们的输入数据的矩阵
  for ( i = 0; i < 4; ++i )
  {
    *(_BYTE *)_ESI[i] = __ROL1__(*(_BYTE *)_ESI[i], i);
    *((_BYTE *)_ESI[i] + 1) = __ROL1__(*((_BYTE *)_ESI[i] + 1), i);
    *((_BYTE *)_ESI[i] + 2) = __ROL1__(*((_BYTE *)_ESI[i] + 2), i);
    v11 = _ESI[i];
    v12 = __ROL1__(*((_BYTE *)v11 + 3), i);     // 每次取一行(4个),将一行中所有元素循环左移(行的下标)
    *((_BYTE *)v11 + 3) = v12;
  }                                             // 一: 字节内位移

3. int3触发断点异常EXCEPTION_BREAKPOINT(异或加密,左移加密)

然后由于没有单个SEH异常处理器形成的SEH链,程序在没调试的时候直接派发给系统最后的一个异常处理器TopLevelExceptionFilter(平常程序会有SEH链来分别处理不同的异常,这个是全部加到了系统最后的一个异常处理器, 然后内部使用了一个case来处理不同的异常)

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case 0x80000003:
      i = 0;                                    // EXCEPTION_BREAKPOINT
      v3 = ptr_to_input_0;
      v4 = *(_BYTE *)(ExceptionInfo->ContextRecord->Eip + 1);// 取int3的下一条指令的一个字节出来进行异或
      do                                        // 0x6E
      {
        *(_BYTE *)v3[i] ^= v4;
        *((_BYTE *)v3[i] + 1) ^= v4;
        *((_BYTE *)v3[i] + 2) ^= v4;
        v5 = v3[i++];
        *((_BYTE *)v5 + 3) ^= v4;               // 每一个都异或了,循环4次是取4
      }
      while ( i < 4 );                          // 异或加密
      HangYiWei();
      ExceptionInfo->ContextRecord->Eip += 2;
      break;

先取了发生异常的那条指令的下一条指令的数据用来当作异或的数据(0x6E)

 

然后对我们的矩阵进行了异或

 

之后又调用函数HangYiWei左移

 

然后通过设置EIP返回

4. 字节代换

返回主函数之后,就会执行

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for ( j = 0; j < 4; ++j )                     // 四: 字节代换
  {
    *(_BYTE *)v13[j] = AES_TABLE[*(unsigned __int8 *)v13[j]];
    *((_BYTE *)v13[j] + 1) = AES_TABLE[*((unsigned __int8 *)v13[j] + 1)];
    *((_BYTE *)v13[j] + 2) = AES_TABLE[*((unsigned __int8 *)v13[j] + 2)];
    v15 = v13[j];
    *((_BYTE *)v15 + 3) = AES_TABLE[*((unsigned __int8 *)v15 + 3)];
  }

5. 触发EXCEPTION_ILLEGAL_INSTRUCTION异常(魔改"逆列混合"加密,行左移)

然后紧接着009F16A8地址开始的四个字节的数据,会触发指令异常(0xC000001D)

 

又会分发到系统的最后一个异常处理器函数TopLevelExceptionFilter

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case 0xC000001D:
      lie_hun_he_ni_yun_suan_mod251_();         // EXCEPTION_ILLEGAL_INSTRUCTION
      HangYiWei();
      ExceptionInfo->ContextRecord->Eip += 2;
      break;

这里执行了两个函数

 

lie_hun_he_ni_yun_suan_mod251函数,"AES的列混合逆运算"并加了mod251的魔改加密函数(恶心)
主要逻辑就是:

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                                                                0xe, 0xb, 0xd, 0x9,
0x9, 0xe, 0xb, 0xd,
0xd, 0x9, 0xe, 0xb,
0xb, 0xd, 0x9, 0xe

这个矩阵和input进行乘法,而且要%251
HangYiWei :

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int HangYiWei()
{
  int result; // eax
  int **ptr_to_input; // edi
  int v2; // ebx
  int *v3; // esi
  int temp; // [esp+Ch] [ebp-4h]
 
  result = 5;
  ptr_to_input = ptr_to_input_0;
  v2 = 4;
  do                                            // 静态分析很耗草稿纸,动态调试吧
                                                // 就是一个逆行移位(左移)
  {
    v3 = *ptr_to_input;
    LOBYTE(temp) = *((_BYTE *)*ptr_to_input + (result - 1) % 4);// 0 1 2 3             二级指针取值
    BYTE1(temp) = *((_BYTE *)*ptr_to_input++ + result % 4);// 1 2 3 0                
                                                // 这里的ptr_to_input++,是对整个循环而言的
                                                // 是先运算再++,++的指针,就是让ptr_to_input换到下一行
    HIBYTE(temp) = *((_BYTE *)v3 + (result + 2) % 4);// 3 0 1 2
    BYTE2(temp) = *((_BYTE *)v3 + (result + 1) % 4);// 2 3 0 1
    *v3 = temp;
    ++result;
    --v2;
  }
  while ( v2 );
  return result;
}

就是一个"行移位"

6. 轮密钥加(就是和对应的key异或)

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v17 = "dministratorx_x" - (char *)ptr_to_input_0;
  v18 = "inistratorx_x" - (char *)ptr_to_input_0;
  l = 4;
  do
  {
    v20 = *v16++;
    *v20 ^= *((_BYTE *)v16 + v17 - 5);
    *((_BYTE *)*(v16 - 1) + 1) ^= *((_BYTE *)v16 + v17 - 4);
    *((_BYTE *)*(v16 - 1) + 2) ^= *((_BYTE *)v16 + v17 - 3);
    *((_BYTE *)*(v16 - 1) + 3) ^= *((_BYTE *)v16 + v18 - 4);
    --l;                                        // 轮密钥加
  }
  while ( l );

7. 触发EXCEPTION_ACCESS_VIOLATION异常(0xC0000005)(列混合,行左移)

又分发到TopLevelExceptionFilter函数进行处理

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case 0xC0000005:
      v6 = ptr_to_input_0;                      // EXCEPTION_ACCESS_VIOLATION
      v7 = 0;
      v24 = 0;
      v26[0] = 0x1010302;
      v26[1] = 0x1030201;
      v26[2] = 0x3020101;
      v26[3] = 0x2010103;                       // 列混合
      do
      {
        v8 = v26;
        v9 = (char *)*v6 + v7;
        v28 = 0;
        v22 = v9;
        v29[0] = *v9;
        v29[1] = *((_BYTE *)v6[1] + v7);
        v29[2] = *((_BYTE *)v6[2] + v7);
        v29[3] = *((_BYTE *)v6[3] + v7);
        v10 = 0;
        v25 = 0;
        do
        {
          v11 = *((_BYTE *)&v28 + v10);
          v12 = 0;
          v23 = (char *)&v28 + v10;
          v27 = v11;
          do
          {
            v13 = *(_BYTE *)v8;
            v14 = 0;
            v15 = v29[v12];
            if ( *(_BYTE *)v8 )
            {
              do
              {
                v16 = v15 ^ v14;
                if ( (v13 & 1) == 0 )
                  v16 = v14;
                v14 = v16;
                v15 = (27 * (v15 >> 7)) ^ (2 * v15);
                v13 >>= 1;
              }
              while ( v13 );
              v11 = v27;
            }
            v11 ^= v14;
            ++v12;
            v8 = (int *)((char *)v8 + 1);
            v27 = v11;
          }
          while ( v12 < 4 );
          *v23 = v11;
          v10 = v25 + 1;
          v25 = v10;
        }
        while ( v10 < 4 );
        v6 = ptr_to_input_0;
        v17 = HIWORD(v28);
        v18 = BYTE1(v28);
        v19 = v24;
        *v22 = v28;
        *((_BYTE *)v6[1] + v19) = v18;
        *((_BYTE *)v6[2] + v19) = v17;
        *((_BYTE *)v6[3] + v19) = HIBYTE(v17);
        v7 = v19 + 1;
        v24 = v7;
      }
      while ( v7 < 4 );
      HangYiWei();                              // 行移位
      v21->ContextRecord->Eip += 3;
      break;
  }
  return -1;
}

就是一个标准的"列混合",然后再次行左移

 

返回main函数触发异常的下一条指令开始执行

8. 比较

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v21 = v27;
  v22 = 12;
  v23 = &cmp_matrix;
  while ( *v21 == *v23 )
  {
    ++v21;
    ++v23;
    v24 = v22 < 4;
    v22 -= 4;
    if ( v24 )
    {
      v25 = "Welcome~\n";
      goto LABEL_21;
    }
  }
  v25 = "WTF???\n";
LABEL_21:
  printf(v25);
  return system((int)"pause");
}

最后的比较矩阵

二:逆那个"mod251的列混合逆运算"加密法

sagemath脚本:

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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, 139],
        [ 9, 14, 11, 13],
        [139, 14, 11],
        [11, 139, 14]
        ]                             //逆那个算法的固定矩阵
 
MT = Matrix(Zmod(251), mt)
inv_mt = MT.inverse()
 
tt = [[0x7e,0xd4,0x4a,0x2d],          //our_input
[0x26,0xc3,0x52,0x9a],
[0x4c,0xa1,0x2b,0x7c],
[0xe5,0x59,0x00,0xfe]]
 
ans = fun(tt)
print(ans)

三:C语言解密

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#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;
}
 
/**
 * 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(矩阵)
 */
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]);
        }
}
/**
 * 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]);
}
/**
 * 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];
}
/**
 * 432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
    };
    //加密过程
 
//    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("cmp_matrix:\n");
    printArray(target);
 
    deShiftRows(target);       //逆左移
 
    deMixColumns(target);      //逆列混合
 
    for(int i = 0; i < 4; i++) {      //逆轮密钥加(异或)
        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];
        }
    }
 
    deShiftRows(target);              //逆左移
 
    printf("在进行特殊的mod251的'列混合的逆运算'之前的matrix:\n");
    printArray(target);
 
    int target2[4][4] = {0xb5, 0xbd, 0x8, 0xc5,
                         0x74, 0x3e, 0x5f, 0x4b,
                         0xdb, 0xc2, 0x1d, 0x2,
                         0x19, 0x42, 0xa0, 0xf6};     //这一个是逆了特殊的mod251的"列混合的逆运算"得到的数据,求救密码学
 
    for(int i = 0; i < 4; i++) {                     //逆字节代换
        for (int j = 0; j < 4; ++j) {
            target2[i][j] = S3[target2[i][j]];
        }
    }
 
    deShiftRows(target2);                           //逆左移
 
    for(int i = 0; i < 4; i++) {
        for (int j = 0; j < 4; ++j) {
            target2[i][j] ^= 0x6e;                  //逆异或0x6E
        }
    }
 
    ror(target2);                                  //逆字节左移
    printArray(target2);
}
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# _*_ coding:utf-8 _*_
# @版权信息:Reversed By SYJ
import binascii
matrix = """bc a3 d1 69
51 52 df 75
2c 1 7c b1
13 25 17 1c"""
for i in matrix.splitlines():
    line = i.split(' ')
    print(line)
# 美团matrix:flag{bca3d169-5152-df75-2c01-7cb11325171c}

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最后于 2021-5-27 03:06 被SYJ-Re编辑 ,原因:
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雪    币:
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师傅可以帮解答一下为什么我在ida时候遇到int3不能进入到异常处理中呢
2021-11-29 02:10
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雪    币: 3660
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你可以看下windows的异常处理,调试器是不一样的,然后ida中你要设置一下分发给程序本身,但是你也得提前在处理int3的异常处理打个断点
2021-12-2 09:58
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