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本帖最后由 skywilling 于 2018-2-25 11:07 编辑 0x00前言从难度上来看，这道题目是这次比赛逆向题目中最难的一个了（当然，这也是相对的，对于入门级的人来说，是一个比较大的挑战了，而对于赛场老手来说，经验丰富，姿势风骚，这种题目也不足为虑。在这里，本人作为一个入门级的菜鸟，当然是从入门级的角度来分析这道题目了）。为什么说这道题目是最难的呢？首先，这道题目涉及到AES(高级加密标准)，而且还是经过修改的；其次，在分析题目过程中，有几个坑（难点）。所以说，与前几个题目相比，难度有所上升，毕竟是最后一道逆向题目，理所当然的就作为压轴题了。这道题目应该是我写的第三篇关于AES加解密的文章了，再次分析AES，对AES又有了新的不同的理解，这是一个循序渐进的过程。下面就开始具体的讲解。0x01工具 虚拟机 创建一个Linux系统了。首先我想到的是Kali系统，这是一个专门用来做网络渗透的Linux系统，里面集成了大量的工具，其中就有逆向工程的工具集。其中就有一个类似于OD的工具可以直接调试ELF文件，然后我就开始一段艰辛调试，然而使用起来不尽人如意，然后就想没有其他更好用的工具呢。最后我想到了IDA 的调试功能，可谓十分强大，几乎涵盖了所有平台的调试功能，使用起来可谓畅快。最后我使用的工具主要是虚拟机创建的Ubuntu系统和IDA，我也大力推荐使用这两个工具。0x02分析文件ELF调试流程和调试PE差不多，首先要看一下ELF文件的一些属性，使用file命令即可，效果如下图：
因为程序是代码和数据的集合。其实在编译完成后，程序中的区块中是含有debug信息和符号信息（这些信息是不会对程序的运行造成影响的），这是为了方便调试而保留的信息，那么抽取的含义就是将debug信息和符号信息从程序中剔除，这样做的目的主要是减少程序的体积（对用户来说）和增加逆向难度（对我们来说）。简单地说，单纯静态分析抽取过的ELF文件将是一场灾难。0x03调试分析调试之前观察程序运行结果是必须的，观察结果将为我们指明调试分析的方向。我们首先尝试几个输入：
Show me your key: 找到程序输入点
[C] 纯文本查看 复制代码
int __cdecl sub_80484B0(int a1)
{
int v1; // ecx
int result; // eax
char v3; // [esp-12h] [ebp-30h]
int v4; // [esp+1h] [ebp-1Dh]
int v5; // [esp+5h] [ebp-19h]
int v6; // [esp+9h] [ebp-15h]
int v7; // [esp+Dh] [ebp-11h]
char v8; // [esp+11h] [ebp-Dh]
unsigned int v9; // [esp+12h] [ebp-Ch]
int *v10; // [esp+16h] [ebp-8h]
v10 = &a1;
v9 = __readgsdword(0x14u);
sub_80515D0((int)"Welcome to Gadgetzan!~");
sub_8071770(1, (int)"Show me your key:", v3);
v4 = 0;
v5 = 0;
v6 = 0;
v7 = 0;
v8 = 0;
sub_8051000((int)"%16s", &v4);
if ( sub_805D820(&v4) == 16 )
{
sub_804A310(&v4);
sub_804A5A0((int)&v4);
}
else
{
sub_80515D0((int)"Key length error!");
}
result = 0;
if ( __readgsdword(0x14u) != v9 )
sub_8071890(v1);
return result;
}
[C] 纯文本查看 复制代码
int __cdecl sub_804A310(int *input)
{
int input_1; // eax
int v2; // eax
int v3; // esi
bool v4; // zf
int v5; // ecx
unsigned int v6; // et1
int input_2; // [esp+18h] [ebp-50h]
int v9; // [esp+1Ch] [ebp-4Ch]
int v10; // [esp+20h] [ebp-48h]
int v11; // [esp+24h] [ebp-44h]
int v12; // [esp+28h] [ebp-40h]
int v13; // [esp+2Ch] [ebp-3Ch]
int v14; // [esp+30h] [ebp-38h]
int v15; // [esp+34h] [ebp-34h]
char v16; // [esp+38h] [ebp-30h]
char v17; // [esp+39h] [ebp-2Fh]
char v18; // [esp+3Ah] [ebp-2Eh]
char v19; // [esp+3Bh] [ebp-2Dh]
char v20; // [esp+3Ch] [ebp-2Ch]
char v21; // [esp+3Dh] [ebp-2Bh]
char v22; // [esp+3Eh] [ebp-2Ah]
char v23; // [esp+3Fh] [ebp-29h]
char v24; // [esp+40h] [ebp-28h]
char v25; // [esp+41h] [ebp-27h]
char v26; // [esp+42h] [ebp-26h]
char v27; // [esp+43h] [ebp-25h]
char v28; // [esp+44h] [ebp-24h]
char v29; // [esp+45h] [ebp-23h]
char v30; // [esp+46h] [ebp-22h]
char v31; // [esp+47h] [ebp-21h]
char v32; // [esp+48h] [ebp-20h]
char v33; // [esp+49h] [ebp-1Fh]
char v34; // [esp+4Ah] [ebp-1Eh]
char v35; // [esp+4Bh] [ebp-1Dh]
char v36; // [esp+4Ch] [ebp-1Ch]
char v37; // [esp+4Dh] [ebp-1Bh]
char v38; // [esp+4Eh] [ebp-1Ah]
char v39; // [esp+4Fh] [ebp-19h]
char v40; // [esp+50h] [ebp-18h]
char v41; // [esp+51h] [ebp-17h]
char v42; // [esp+52h] [ebp-16h]
char v43; // [esp+53h] [ebp-15h]
char v44; // [esp+54h] [ebp-14h]
char v45; // [esp+55h] [ebp-13h]
char v46; // [esp+56h] [ebp-12h]
char v47; // [esp+57h] [ebp-11h]
unsigned int v48; // [esp+58h] [ebp-10h]
v16 = 0xE6u;
v48 = __readgsdword(0x14u);
v17 = 0xB8u;
v18 = 0xA1u;
v19 = 0xE3u;
v20 = 0x80u;
v21 = 0x82u;
v22 = 0xE6u;
v23 = 0xB8u;
v24 = 0xA1u;
v25 = 0xE3u;
v26 = 0x80u;
v27 = 0x82u;
v28 = 0xE6u;
v29 = 0xB8u;
v30 = 0xA1u;
v31 = 0xE3u;
v32 = 0x80u;
v33 = 0x82u;
v34 = 0xE6u;
v35 = 0xB8u;
v36 = 0xA1u;
v37 = 0xE3u;
v38 = 0x80u;
v39 = 0x82u;
v40 = 0xE6u;
v41 = 0xB8u;
v42 = 0xA1u;
v43 = 0xE3u;
input_1 = *input;
v44 = 0x80u;
v45 = 0x82u;
v46 = 0xE6u;
input_2 = input_1;
v2 = input[1];
v47 = 0xB8u;
dword_80EFB24 = 8;
dword_80EFB28 = 14;
v9 = v2;
v10 = input[2];
v11 = input[3];
v3 = sub_805B3F0(60 * dword_80EE084);
sub_8049F00((int)&v16, v3);
sub_804A1A0(&input_2, &v12, v3);
*input = v12;
input[1] = v13;
input[2] = v14;
v6 = __readgsdword(0x14u);
v5 = v6 ^ v48;
v4 = v6 == v48;
input[3] = v15;
if ( !v4 )
sub_8071890(v5);
return 0;
} [C] 纯文本查看 复制代码
init=[0xE6,0xB8,0xA1,0xE3,0x80,0x82,0xE6,0xB8,0xA1,0xE3,0x80,0x82,0xE6,0xB8,0xA1,
0xE3,0x80,0x82,0xE6,0xB8,0xA1,0xE3,0x80,0x82,0xE6,0xB8,0xA1,0xE3,0x80,0x82,0xE6,0xB8] [C] 纯文本查看 复制代码
int __cdecl sub_8049F00(int input, int output)
{
int input_1; // ecx
int v3; // eax
int v4; // esi
int v5; // edx
int v6; // ebp
int v7; // esi
unsigned __int8 v8; // bl
char v9; // dl
char v10; // al
int v11; // edx
int *v12; // edx
unsigned __int8 v13; // al
int v14; // ecx
char v15; // bl
int result; // eax
unsigned int v17; // et1
int *i; // edx
signed int v19; // [esp+4h] [ebp-38h]
int v20; // [esp+8h] [ebp-34h]
unsigned __int8 v21; // [esp+Ch] [ebp-30h]
__int16 v22; // [esp+Dh] [ebp-2Fh]
unsigned __int8 v23; // [esp+Fh] [ebp-2Dh]
unsigned __int8 v24; // [esp+18h] [ebp-24h]
char v25[3]; // [esp+19h] [ebp-23h]
unsigned int v26; // [esp+1Ch] [ebp-20h]
v26 = __readgsdword(0x14u);
input_1 = input;
v23 = dword_80EE084 * (dword_80EFB28 + 1);
v19 = dword_80EFB24;
if ( dword_80EFB24 > 0 )
{
v3 = 0;
v4 = 0;
do
{
v5 = 4 * v3;
++v4;
*(_BYTE *)(output + 4 * v3) = *(_BYTE *)(input + 4 * v3);
*(_BYTE *)(output + v5 + 1) = *(_BYTE *)(input + 4 * v3 + 1);
*(_BYTE *)(output + v5 + 2) = *(_BYTE *)(input + 4 * v3 + 2);
*(_BYTE *)(output + v5 + 3) = *(_BYTE *)(input + 4 * v3 + 3);
v3 = (unsigned __int8)v4;
}
while ( (unsigned __int8)v4 < dword_80EFB24 );
v19 = dword_80EFB24;
}
v21 = v19;
if ( v23 > (unsigned __int8)v19 )
{
while ( 1 )
{
v6 = v21;
v7 = 4 * (v21 - 1);
v8 = *(_BYTE *)(output + v7);
v9 = *(_BYTE *)(output + v7 + 3);
v10 = *(_BYTE *)(output + v7 + 2);
input_1 = *(unsigned __int8 *)(output + v7 + 1);
v24 = *(_BYTE *)(output + v7);
HIBYTE(v22) = v9;
v25[2] = v9;
LOBYTE(v22) = v10;
v25[1] = v10;
v25[0] = input_1;
v20 = v19;
v11 = v21 % v19;
if ( v11 )
{
if ( v19 > 6 && v11 == 4 )
{
for ( i = (int *)&v24; ; v8 = *(_BYTE *)i )
{
i = (int *)((char *)i + 1);
*((_BYTE *)i - 1) = byte_80BDE60[16 * (v8 >> 4) + (v8 & 0xF)];
if ( i == (int *)&v26 )
break;
}
v8 = v24;
input_1 = (unsigned __int8)v25[0];
v22 = *(_WORD *)&v25[1];
}
}
else
{
v24 = input_1;
v25[2] = v8;
v12 = (int *)&v24;
*(_WORD *)v25 = v22;
while ( 1 )
{
v13 = input_1;
v14 = input_1 & 0xF;
v12 = (int *)((char *)v12 + 1);
*((_BYTE *)v12 - 1) = byte_80BDE60[16 * (v13 >> 4) + v14];
if ( &v26 == (unsigned int *)v12 )
break;
LOBYTE(input_1) = *(_BYTE *)v12;
}
if ( (unsigned __int8)(v21 / v19) == 1 )
{
byte_80EE080 = 1;
v15 = 1;
}
else
{
v15 = byte_80EE080;
if ( (unsigned __int8)(v21 / v19) > 1u )
{
sub_80489A0(v14, v21 % v19);
v15 = byte_80EE080;
v20 = dword_80EFB24;
}
}
input_1 = (unsigned __int8)v25[0];
v8 = v24 ^ v15;
LOBYTE(input_1) = byte_80EE081 ^ v25[0];
v22 = word_80EE082 ^ *(_WORD *)&v25[1];
*(_WORD *)&v25[1] ^= word_80EE082;
v24 = v8;
v25[0] ^= byte_80EE081;
}
++v21;
*(_BYTE *)(output + v7 + 4) = *(_BYTE *)(output + 4 * (v6 - v20)) ^ v8;
LOBYTE(input_1) = *(_BYTE *)(output + 4 * (v6 - dword_80EFB24) + 1) ^ input_1;
*(_BYTE *)(output + v7 + 5) = input_1;
*(_WORD *)(output + v7 + 6) = *(_WORD *)(output + 4 * (v6 - dword_80EFB24) + 2) ^ v22;
if ( v23 <= v21 )
break;
v19 = dword_80EFB24;
}
}
v17 = __readgsdword(0x14u);
result = v17 ^ v26;
if ( v17 != v26 )
sub_8071890(input_1);
return result;
} [Python] 纯文本查看 复制代码
def shiftup_4(temp):
i=temp[0]
temp[0]=temp[1]
temp[1]=temp[2]
temp[2]=temp[3]
temp[3]=i
def substitution(temp,s_box):
i=0
while i<len(temp):
temp[i]=s_box[temp[i]]
i+=1
def xor(temp,xor_temp):
i=0
while i<len(temp):
temp[i]^=xor_temp[i]
i+=1
def func1(temp,init,s_box):
i=8
while i<60:
for j in range(4):
temp[j]^=init[32*(int(i/8)-1)+4*(i%8)+j]
init.append(temp[j])
i += 1
#print("=======%X======" % i)
if i%8==0:
shiftup_4(temp)
substitution(temp, s_box)
#printf(temp,4)
xor(temp, [2**(int(i/8)-1), 0, 0, 0])
if i%8==4:
substitution(temp,s_box)
#printf(init[32:],len(init[32:]))
init=[0xE6,0xB8,0xA1,0xE3,0x80,0x82,0xE6,0xB8,0xA1,0xE3,0x80,0x82,0xE6,0xB8,0xA1,
0xE3,0x80,0x82,0xE6,0xB8,0xA1,0xE3,0x80,0x82,0xE6,0xB8,0xA1,0xE3,0x80,0x82,0xE6,0xB8]
####扩展密钥#####
temp=init[28:32]
shiftup_4(temp)
substitution(temp, s_box)
xor(temp, [1, 0, 0, 0])
func1(temp,init,s_box)
############## [C] 纯文本查看 复制代码
0EE084;
v5 = alloca(4 * dword_80EE084);
v6 = &v18;
do
{
if ( v23 > 0 )
{
v7 = 0;
v8 = 0;
v22 = v6;
do
{
++v8;
*((_BYTE *)v22 + v7 + v3) = *(_BYTE *)(v21 + 4 * v7 + v4);
v7 = (unsigned __int8)v8;
}
while ( v23 > (unsigned __int8)v8 );
v6 = v22;
}
++v4;
v3 += v23;
}
while ( v4 != 4 );
v9 = 1;
v10 = 1;
sub_8049C60(v6, v20, 0);
if ( dword_80EFB28 > 1 )
{
do
{
++v10;
sub_8049E50(v6);
sub_8049DC0(v6);
sub_8049D00(v6);
sub_8049C60(v6, v20, v9);
sub_80495C0(v6);
v9 = (unsigned __int8)v10;
}
while ( (unsigned __int8)v10 < dword_80EFB28 );
}
v11 = 0;
sub_8049E50(v6);
sub_8049DC0(v6);
sub_8049C60(v6, v20, (unsigned __int8)dword_80EFB28);
v13 = dword_80EE084;
v14 = v19;
v23 = (signed int)v6;
do
{
if ( v13 > 0 )
{
v15 = 0;
v12 = 0;
do
{
++v12;
*(_BYTE *)(v14 + 4 * v15 + v11) = *(_BYTE *)(v23 + v15 + v11 * v13);
v13 = dword_80EE084;
v15 = (unsigned __int8)v12;
}
while ( (unsigned __int8)v12 < dword_80EE084 );
}
++v11;
}
while ( v11 != 4 );
v17 = __readgsdword(0x14u);
result = v17 ^ v24;
if ( v17 != v24 )
sub_8071890(v12);
return result;
} [Python] 纯文本查看 复制代码
temp=to_ord(input)
trans(temp)
xor_col(temp,key_groups,1)
i=2
while i<=0xE:
sub_byte(temp,s_box)
shift_row(temp)
mix_col(temp,s)
xor_col(temp,key_groups,i)
xor_key(temp,key)
i+=1
sub_byte(temp,s_box)
shift_row(temp)
xor_col(temp,key_groups,i)
trans(temp) [C] 纯文本查看 复制代码
unsigned int __cdecl sub_80492B0(int *a1)
{
int v1; // edx
unsigned int result; // eax
int v3; // eax
int v4; // eax
v1 = *a1;
result = *(unsigned __int8 *)*a1 - 12;
while ( 1 )
{
switch ( result )
{
case 0u:
sub_8048F40(a1, *(char *)(v1 + 1));
v3 = *a1;
goto LABEL_5;
case 8u:
v3 = v1 + 2;
if ( *(_DWORD *)(a1[1] + 28) == 1 )
goto LABEL_4;
goto LABEL_5;
case 9u:
sub_8048C90((int)a1, *(char *)(v1 + 1), *(char *)(v1 + 2));
v3 = *a1;
goto LABEL_5;
case 0x1Eu:
v3 = v1 + 2;
if ( *(_DWORD *)(a1[1] + 28) <= 1u )
goto LABEL_4;
goto LABEL_5;
case 0x21u:
sub_8049060((int)a1, *(char *)(v1 + 1), *(char *)(v1 + 2));
v3 = *a1;
goto LABEL_5;
case 0x25u:
sub_8048D60(a1, *(char *)(v1 + 1), *(char *)(v1 + 2));
v3 = *a1;
goto LABEL_5;
case 0x2Au:
v3 = v1 + 2;
if ( *(_DWORD *)(a1[1] + 28) == 2 )
goto LABEL_4;
goto LABEL_5;
case 0x5Bu:
sub_8048FF0(a1, *(char *)(v1 + 1));
v3 = *a1;
goto LABEL_5;
case 0x64u:
sub_8048E40((int)a1, *(char *)(v1 + 1), *(char *)(v1 + 2));
v3 = *a1;
goto LABEL_5;
case 0x65u:
sub_8049260(a1, *(char *)(v1 + 1), 4);
goto LABEL_14;
case 0x67u:
v3 = v1 + 2;
if ( *(_DWORD *)(a1[1] + 28) )
goto LABEL_4;
goto LABEL_5;
case 0x77u:
sub_80490E0(a1, *(char *)(v1 + 1), *(_DWORD *)(v1 + 2), 1);
goto LABEL_10;
case 0x79u:
sub_8048C10(a1, *(char *)(v1 + 1), *(char *)(v1 + 2));
v3 = *a1;
goto LABEL_5;
case 0x7Au:
sub_8049260(a1, *(char *)(v1 + 1), 1);
goto LABEL_14;
case 0x7Eu:
sub_80490A0(a1, *(char *)(v1 + 1), *(_DWORD *)(v1 + 2), 1);
goto LABEL_12;
case 0x8Du:
sub_80490E0(a1, *(char *)(v1 + 1), *(_DWORD *)(v1 + 2), 4);
goto LABEL_10;
case 0x94u:
sub_8048F90(a1, *(char *)(v1 + 1));
v3 = *a1;
goto LABEL_5;
case 0x98u:
v3 = v1 + 2;
if ( *(_DWORD *)(a1[1] + 28) != 1 )
goto LABEL_4;
goto LABEL_5;
case 0x9Du:
sub_8048DC0(a1, *(char *)(v1 + 1), *(char *)(v1 + 2));
v3 = *a1;
goto LABEL_5;
case 0xA0u:
goto LABEL_4;
case 0xABu:
sub_8048CF0(a1, *(char *)(v1 + 1), *(char *)(v1 + 2));
v3 = *a1;
goto LABEL_5;
case 0xB5u:
sub_8048B90(a1, *(char *)(v1 + 1), *(char *)(v1 + 2));
v3 = *a1;
goto LABEL_5;
case 0xB7u:
sub_8048EC0((int)a1, *(char *)(v1 + 1), *(char *)(v1 + 2));
v3 = *a1;
goto LABEL_5;
case 0xBFu:
sub_8049030(a1, *(char *)(v1 + 1));
v3 = *a1;
goto LABEL_5;
case 0xD9u:
v3 = v1 + 2;
a1[2] = *(_DWORD *)(v1 + 1);
goto LABEL_5;
case 0xDDu:
sub_80490E0(a1, *(char *)(v1 + 1), *(_DWORD *)(v1 + 2), 2);
LABEL_10:
v3 = *a1;
goto LABEL_5;
case 0xE6u:
sub_80490A0(a1, *(char *)(v1 + 1), *(_DWORD *)(v1 + 2), 2);
goto LABEL_12;
case 0xEDu:
sub_8049260(a1, *(char *)(v1 + 1), 2);
LABEL_14:
v3 = *a1;
goto LABEL_5;
case 0xEFu:
v3 = v1 + 2;
if ( !*(_DWORD *)(a1[1] + 28) )
LABEL_4:
v3 = v1 + *(_DWORD *)(v1 + 1) - 3;
goto LABEL_5;
case 0xF2u:
sub_80490A0(a1, *(char *)(v1 + 1), *(_DWORD *)(v1 + 2), 4);
LABEL_12:
v3 = *a1;
goto LABEL_5;
case 0xF3u:
return result;
default:
do
{
v3 = v1 - 2;
LABEL_5:
v1 = v3 + 3;
v4 = *(unsigned __int8 *)(v3 + 3);
*a1 = v1;
result = v4 - 12;
}
while ( result > 0xF3 );
break;
}
}
} [Python] 纯文本查看 复制代码
def xor_key(temp,key):
for i in range(15):
temp[i] ^= key[i]
temp[14-i]^=temp[15-i] temp[index] ^= key[index]，是没有后面的代码的，所以才说这是一个修改过的AES加密，而且S盒都换了新的，这也奠定了解密满是坑的基础。到这里AES就结束了，接下里就是判断结果了。[C] 纯文本查看 复制代码
int __cdecl sub_804A5A0(int input)
{
char v1; // bl
int v2; // eax
int v3; // esi
signed int v4; // eax
int v5; // ecx
int v6; // eax
int v7; // esi
__int16 *v8; // ebp
int v9; // edi
unsigned int v10; // edx
int v11; // ecx
int v12; // ebx
int v13; // eax
__int16 v14; // ax
unsigned __int8 v16; // [esp+16h] [ebp-36h]
unsigned __int16 i; // [esp+16h] [ebp-36h]
int v18; // [esp+18h] [ebp-34h]
int v19; // [esp+1Ch] [ebp-30h]
int v20; // [esp+20h] [ebp-2Ch]
unsigned __int8 *v21; // [esp+24h] [ebp-28h]
int v22; // [esp+2Ch] [ebp-20h]
v1 = 88;
v2 = sub_805BC30(256, 1);
v22 = v2;
v21 = (unsigned __int8 *)&unk_80BDE68;
v3 = v2;
v4 = 54;
v20 = 0;
while ( 1 )
{
v16 = v1;
v18 = *(unsigned __int8 *)(input + v20);
v5 = 0;
v19 = *(unsigned __int8 *)(input - v20 + 15);
while ( 1 )
{
*(_BYTE *)(v3 + v4) = (v18 >> v5) & 1;
v6 = v19 >> v5++;
*(_BYTE *)(v3 + v16) = v6 & 1;
if ( v5 == 8 )
break;
v4 = (unsigned __int8)byte_80BDE60[8 * v20 + v5];
v16 = v21[v5 + 120];
}
if ( ++v20 == 16 )
break;
v4 = *v21;
v1 = v21[128];
v21 += 8;
}
v7 = v22;
v8 = (__int16 *)&unk_80BDC42;
v9 = 0;
v10 = 0xFFFF8EBC;
for ( i = 0x86C1u; ; i = v14 )
{
v11 = 0;
v12 = 0;
while ( 1 )
{
v13 = *(unsigned __int8 *)(v7 + 4 * v11);
++v11;
v12 ^= v13 * v10;
if ( v11 == 16 )
break;
v10 = (unsigned __int16)word_80BDC60[v9 + v11];
}
if ( (_WORD)v12 != i )
break;
++v7;
v9 += 16;
if ( v8 == word_80BDC60 )
{
sub_80515D0((int)"Good job! The flag is your input...");
sub_804A470(v22);
sub_805B900(v22);
return 0;
}
v14 = *v8;
v10 = (unsigned __int16)word_80BDC60[v9];
++v8;
}
sub_80515D0((int)"Wrong key!");
return 0;
} Good job! The flag is your input...，它就我们要的输出结果。给出还原代码：[Python] 纯文本查看 复制代码
#转为二进制
def to_bin(temp,s_box,ans):
for i in range(16):
for j in range(8):
ans[s_box[i*8+j]]=(temp[i]>>j)&1
ans[s_box[(i+16)*8+j]]=(temp[15-i]>>j)&1 [Python] 纯文本查看 复制代码
#检测结果
def check(v8,data,ans):
for i in range(16):
final = v8[i * 2] + (v8[i * 2 + 1] << 8)
k=0
for j in range(16):
d=data[(i*16+j)*2]+(data[(i*16+j)*2+1]<<8)
k=k^(ans[j*16+i]*d)
if k!=final:
return 0
return 1 0x04解密解密说白了就是加密步骤反过来执行。破解 了（穷举），官方也是这么说的。通过对check()函数的理解，给出inv_check()爆破函数：[Python] 纯文本查看 复制代码
#猜测得到ans
def inv_check(v8,data,ans,guess):
for i in range(16):
final = v8[i * 2] + (v8[i * 2 + 1] << 8)
for x in range(0x10000):
k=0
for j in range(16):
d=data[(i*16+j)*2]+(data[(i*16+j)*2+1]<<8)
k^=(d*guess[x*16+j])
if k==final:
for j in range(16):
ans[j*16+i]=guess[x*16+j] [C] 纯文本查看 复制代码
v = s_box[16*i+j]
i+16*j == inv_s_box[16*(v&0xf)+v/0x10] [Python] 纯文本查看 复制代码
def get_inv_s(s):
u = [0 for x in range(16)]
x=[1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1]
for i in range(4):
for j in range(4):
u[(3-j)*4+i]=s[((3-j)-i+4)%4]
for a in range(0x10):
for b in range(0x10):
for c in range(0x10):
for d in range(0x10):
k=u[:]
mix_col(k,[a,b,c,d])
n=0
for i in range(16):
if(k[i]==x[i]):
n+=1
if n==16:
return [a,b,c,d]
return None [C] 纯文本查看 复制代码
s = [0xD, 0xE, 0xF, 0xD]
0x05成功运行成功运行后的效果，如下图
附件：https://pan.baidu.com/s/1jKek3Ng 密码：9rlr 版权声明：允许转载，但是一定要注明出处 。
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发表于 2018-1-10 18:27
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发表于 2018-1-25 20:32
