本文为看雪论坛精华文章
看雪论坛作者ID：榆一
解题过程
先查壳：
无壳，直接拖入IDA找到main函数分析：
初步分析，该程序需要输入两次，分别对应两个验证函数sub_7FF634B112B0和sub_7FF634B11A90，先看看第一个验证函数干了啥：
首先进行规定输入字符串的长度为22，然后有几个等式，这几个等式中的数据可以看出是跟我们输入数据的后16位有关，最终v11的结果要等于0x3EBB0EFAF301FC，猜测后续要进行解方程求解。往下看：
下面就使用了unicorn的函数，uc_open就是c调用unicorn时初始化unicorn的环境，然后第一个参数就是具体环境，第二个参数为具体的模式，我们查一下3和4具体代表啥：
说明初始化的是mips环境，且是x86模式。继续往下看：
从uc_mem_write可以看出mips的代码是从unk_7FF634B13340中提取出来的，大小为272。然后0x11000，0x12000，0x13000地址处填入的应该是mips代码中所需要的数据。其中byte_7FF634B15656和byte_7FF634B1565E是我们所输入的数据中的后16位。
这里有个uc_hook_add的函数，这个是unicorn的hook机制，第三个参数为4，代表unicorn每执行一次模拟的代码，就会触发一次hook机制，第四个参数是回调函数。接下来的操作就是初始化一些寄存器环境，然后进行模拟代码的执行，最后执行完，读取各个寄存器的值，进行验证。sub_7FF634B11000为回调函数，我们跟进去看下：
__int64 __fastcall sub_7FF634B11000(__int64 a1, __int64 a2){__int64 result; // raxint v5; // [rsp+20h] [rbp-28h] BYREFint v6; // [rsp+24h] [rbp-24h] BYREFint v7; // [rsp+28h] [rbp-20h] BYREFint v8; // [rsp+2Ch] [rbp-1Ch] BYREFint v9[6]; // [rsp+30h] [rbp-18h] BYREFint v10; // [rsp+58h] [rbp+10h] BYREFuc_reg_read(a1, 11i64, &v10);uc_reg_read(a1, 12i64, &v5);uc_reg_read(a1, 13i64, &v6);uc_reg_read(a1, 14i64, &v7);uc_reg_read(a1, 15i64, &v8);result = uc_reg_read(a1, 16i64, v9);switch ( a2 ) // a2是地址{case 0x10010i64:result = uc_reg_read(a1, 11i64, &v10);if ( v10 != 0x2F2E ){printf("You died before you killed anyone.n");uc_emu_stop(a1);exit(-1);}return result;case 0x10020i64:result = uc_reg_read(a1, 12i64, &v5);if ( v5 != 0x282A ){printf("You died when you killed only one.n");uc_emu_stop(a1);exit(-1);}return result;case 0x10030i64:result = uc_reg_read(a1, 13i64, &v6);if ( v6 != 0x2C42 ){printf("Nice! Double kill, but died.n");uc_emu_stop(a1);exit(-1);}return result;case 0x10040i64:result = uc_reg_read(a1, 14i64, &v7);if ( v7 != 0x2A8A ){printf("Awesome! Triple Kill, but interrupted.n");uc_emu_stop(a1);exit(-1);}return result;case 0x10050i64:result = uc_reg_read(a1, 15i64, &v8);if ( v8 != 0x13E0 ){printf("Unimaginable! Quadra Kill, but emm...You know what I want to say.n");uc_emu_stop(a1);exit(-1);}return result;case 0x10060i64:result = uc_reg_read(a1, 16i64, v9);if ( v9[0] != 0x36D4 ){printf("Incredible! Penta Kill, but frankly, you still died.n");uc_emu_stop(a1);exit(-1);}return result;default:return result;}return result;}
看着难受，而且不能F5看算法，索性我们自己写一个unicorn调试一下这个代码：
from unicorn import *from unicorn.x86_const import *from unicorn.arm_const import *from unicorn.mips_const import *from capstone import *with open('mips', 'rb') as file:#读代码段MIPS_CODE = file.read() # 读取代码class UnidbgMips:def __init__(self):# x32程序mu = Uc(UC_ARCH_MIPS, UC_MODE_32)mu.mem_map(0x10000, 0x200000)mu.mem_write(0x10000,MIPS_CODE)mu.mem_write(0x11000,b"zjgcjyx00")mu.mem_write(0x12000,b"xFCx01xF3xFAx0ExBBx3Ex00") #输入假的值mu.mem_write(0x13000,b"x00x00x00x00x00x00x00x00")mu.reg_write(UC_MIPS_REG_T1, 0x30)#输入假的值mu.reg_write(UC_MIPS_REG_T2, 0x31)mu.reg_write(UC_MIPS_REG_T3, 0x32)mu.reg_write(UC_MIPS_REG_T4, 0x33)mu.reg_write(UC_MIPS_REG_T5, 0x34)mu.reg_write(UC_MIPS_REG_T6, 0x35)mu.hook_add(UC_HOOK_CODE, self.hook_code)self.mu=mu# 反汇编引擎self.md = Cs(CS_ARCH_MIPS, CS_MODE_32)def hook_code(self, mu, address, size, data):disasm = self.md.disasm(mu.mem_read(address, size), address)for i in disasm:print("0x%x:t%st%s" %(i.address,i.mnemonic,i.op_str))def start(self):try:self.mu.emu_start(0x10000,0x10110)except:passif __name__ == '__main__':UnidbgMips().start()
仔细观察可以发现，这些指令有这重复的操作，四句指令为一组：
将t0寄存器的值进行一个输出，可以发现这四句指令具体的操作就是将0x11000地址处的zjgcjy这串字符，一个个取出，然后跟我们输入值的前6个字符一个个取出进行相乘。得到一个结果，然后我们回去看hook的回调函数：
可以发现0x10010就是我们完成第一组指令后的地址 他这里将t1的值取出判断是不是等于0x2f2e，说明我们输入值的第一个字符*z=0x2F2E，后面可以因此类推，得到前6个字符：
using namespace std;unsigned char flag[50] = { 0 };void getFirstHalfFlag(){memset(flag, 0, 50);unsigned int res[] = {0x2F2E,0x282A,0x2C42,0x2A8A,0x13E0,0x36D4};unsigned char key[] = "zjgcjy";for (int i = 0; i < 6; i++) {flag[i] = res[i] / key[i];}printf("%srn", flag);}int main(){getFirstHalfFlag();return 0;}
cann0t
发现也是以组为单位的，分别取出0x12000地址中的值和0x13000地址中的值进行一个相加得到结果，然后这两个地址+1取下一个,以此类推得到t1,t2,t3,t4,t5,t6,t7,t8寄存器的值。再回过头来看unicorn执行结束后的判断：
t1,t2,t3,t4,t5,t6,t7,t8寄存器的值进行验证。
再根据这些等式，得到一组方程两元一次方程，这里只写一个举个例子：
x1-y1=0xFC
x1+y1=0xC2
解出x1,y1，以此类推，直接写脚本，由于这里存在溢出问题，所以我采用爆破的方式，准确一点。
using namespace std;unsigned char flag[50] = { 0 };void getFirstHalfFlag(){memset(flag, 0, 50);unsigned int res[] = {0x2F2E,0x282A,0x2C42,0x2A8A,0x13E0,0x36D4};unsigned char key[] = "zjgcjy";for (int i = 0; i < 6; i++) {flag[i] = res[i] / key[i];}unsigned char key1[] = {0xFC,0x1,0xF3,0xFA,0xE,0xBB,0x3E,0x0};unsigned char key2[] = {0xC2,0xC3,0xD7,0xC4,0xDA,0xA5,0xA0,0xBE};for (int i = 0; i < 8; i++) {for (unsigned char a = 32; a <= 126; a++) {for (unsigned char b = 32; b <= 126; b++) {unsigned char res1 = a - b;unsigned char res2 = a + b;if (res1 == key1[i] && res2 == key2[i]) {flag[6 + i] = a;flag[14 + i] = b;break;}}}}printf("%srn", flag);}int main(){getFirstHalfFlag();return 0;}
cann0t_be_t0ocarefu1
先验证输入的长度为20，再公共sub_7FF634B119F0验证输入的前四个字符。查看一波sub_7FF634B119F0：
发现有一个表，然后有一个异或操作，由于这里有一个移位操作，存在丢失数据，而且就验证四个字符，所以我们直接爆破他。
#include<iostream>#include<Windows.h>using namespace std;unsigned int key[] = {0x0,0xf26b8303,0xe13b70f7,0x1350f3f4,0xc79a971f,0x35f1141c,0x26a1e7e8,0xd4ca64eb,0x8ad958cf,0x78b2dbcc,0x6be22838,0x9989ab3b,0x4d43cfd0,0xbf284cd3,0xac78bf27,0x5e133c24,0x105ec76f,0xe235446c,0xf165b798,0x30e349b,0xd7c45070,0x25afd373,0x36ff2087,0xc494a384,0x9a879fa0,0x68ec1ca3,0x7bbcef57,0x89d76c54,0x5d1d08bf,0xaf768bbc,0xbc267848,0x4e4dfb4b,0x20bd8ede,0xd2d60ddd,0xc186fe29,0x33ed7d2a,0xe72719c1,0x154c9ac2,0x61c6936,0xf477ea35,0xaa64d611,0x580f5512,0x4b5fa6e6,0xb93425e5,0x6dfe410e,0x9f95c20d,0x8cc531f9,0x7eaeb2fa,0x30e349b1,0xc288cab2,0xd1d83946,0x23b3ba45,0xf779deae,0x5125dad,0x1642ae59,0xe4292d5a,0xba3a117e,0x4851927d,0x5b016189,0xa96ae28a,0x7da08661,0x8fcb0562,0x9c9bf696,0x6ef07595,0x417b1dbc,0xb3109ebf,0xa0406d4b,0x522bee48,0x86e18aa3,0x748a09a0,0x67dafa54,0x95b17957,0xcba24573,0x39c9c670,0x2a993584,0xd8f2b687,0xc38d26c,0xfe53516f,0xed03a29b,0x1f682198,0x5125dad3,0xa34e59d0,0xb01eaa24,0x42752927,0x96bf4dcc,0x64d4cecf,0x77843d3b,0x85efbe38,0xdbfc821c,0x2997011f,0x3ac7f2eb,0xc8ac71e8,0x1c661503,0xee0d9600,0xfd5d65f4,0xf36e6f7,0x61c69362,0x93ad1061,0x80fde395,0x72966096,0xa65c047d,0x5437877e,0x4767748a,0xb50cf789,0xeb1fcbad,0x197448ae,0xa24bb5a,0xf84f3859,0x2c855cb2,0xdeeedfb1,0xcdbe2c45,0x3fd5af46,0x7198540d,0x83f3d70e,0x90a324fa,0x62c8a7f9,0xb602c312,0x44694011,0x5739b3e5,0xa55230e6,0xfb410cc2,0x92a8fc1,0x1a7a7c35,0xe811ff36,0x3cdb9bdd,0xceb018de,0xdde0eb2a,0x2f8b6829,0x82f63b78,0x709db87b,0x63cd4b8f,0x91a6c88c,0x456cac67,0xb7072f64,0xa457dc90,0x563c5f93,0x82f63b7,0xfa44e0b4,0xe9141340,0x1b7f9043,0xcfb5f4a8,0x3dde77ab,0x2e8e845f,0xdce5075c,0x92a8fc17,0x60c37f14,0x73938ce0,0x81f80fe3,0x55326b08,0xa759e80b,0xb4091bff,0x466298fc,0x1871a4d8,0xea1a27db,0xf94ad42f,0xb21572c,0xdfeb33c7,0x2d80b0c4,0x3ed04330,0xccbbc033,0xa24bb5a6,0x502036a5,0x4370c551,0xb11b4652,0x65d122b9,0x97baa1ba,0x84ea524e,0x7681d14d,0x2892ed69,0xdaf96e6a,0xc9a99d9e,0x3bc21e9d,0xef087a76,0x1d63f975,0xe330a81,0xfc588982,0xb21572c9,0x407ef1ca,0x532e023e,0xa145813d,0x758fe5d6,0x87e466d5,0x94b49521,0x66df1622,0x38cc2a06,0xcaa7a905,0xd9f75af1,0x2b9cd9f2,0xff56bd19,0xd3d3e1a,0x1e6dcdee,0xec064eed,0xc38d26c4,0x31e6a5c7,0x22b65633,0xd0ddd530,0x417b1db,0xf67c32d8,0xe52cc12c,0x1747422f,0x49547e0b,0xbb3ffd08,0xa86f0efc,0x5a048dff,0x8ecee914,0x7ca56a17,0x6ff599e3,0x9d9e1ae0,0xd3d3e1ab,0x21b862a8,0x32e8915c,0xc083125f,0x144976b4,0xe622f5b7,0xf5720643,0x7198540,0x590ab964,0xab613a67,0xb831c993,0x4a5a4a90,0x9e902e7b,0x6cfbad78,0x7fab5e8c,0x8dc0dd8f,0xe330a81a,0x115b2b19,0x20bd8ed,0xf0605bee,0x24aa3f05,0xd6c1bc06,0xc5914ff2,0x37faccf1,0x69e9f0d5,0x9b8273d6,0x88d28022,0x7ab90321,0xae7367ca,0x5c18e4c9,0x4f48173d,0xbd23943e,0xf36e6f75,0x105ec76,0x12551f82,0xe03e9c81,0x34f4f86a,0xc69f7b69,0xd5cf889d,0x27a40b9e,0x79b737ba,0x8bdcb4b9,0x988c474d,0x6ae7c44e,0xbe2da0a5,0x4c4623a6,0x5f16d052,0xad7d5351};void getLastHalfFlag(){unsigned int v1;DWORD res = 0xCAFABCBC;res = ~res;for (DWORD i = 0x32323232; i <= 0x7E7E7E7E; i++) {v1 = -1;unsigned char *cRes = (unsigned char*)&i;for (int j = 0; j < 4; j++) {unsigned char value = cRes[j] ^ v1;v1 = ((v1 >> 8) ^ key[value]);}if (res == v1) {printf("%xrn", i);break;}}}int main(){getLastHalfFlag();return 0;}
0x6e65687转化为字符串"when"
后面的逻辑主要是验证输入的后16个字符，这里uc_open的第一个参数代码的是ARM架构，然后ARM的代码是从unk_7FF634B139B0开始的，大小为0x400，我们保存下来。偷个懒，用IDA的F5识别出算法。
void __noreturn sub_0(){char *v0; // r2char *v1; // r2char *v2; // r2char *v3; // r2char *v4; // r2char *v5; // r2char *v6; // r3char *v7; // r2char *v8; // r3char *v9; // r3char v10[100]; // [sp+0h] [bp-8Ch] BYREFchar v11[28]; // [sp+64h] [bp-28h] BYREFint i; // [sp+80h] [bp-Ch]char *v13; // [sp+84h] [bp-8h]qmemcpy(v11, ")8FP>6^B=G6@>X*P<G=B)1 ", 24);v13 = v10;for ( i = 0; i <= 13; i += 3 ) // 四个为一组{v0 = v13++;*v0 = (*(_BYTE *)(i + 0x21024) >> 2) + 33; // 通过这个得到第i个字符的高6位v1 = v13++;*v1 = ((16 * *(_BYTE *)(i + 135204)) & 0x30 | (*(_BYTE *)(i + 135205) >> 4)) + 33;// 这个结果包含了第i个字符的低2位和第i+1个字符的高4位v2 = v13++;*v2 = ((4 * *(_BYTE *)(i + 135205)) & 0x3C | (*(_BYTE *)(i + 135206) >> 6)) + 33;// 这个结果包含了第i+1个字符的低4位和第i+2个字符的高两位v3 = v13++;*v3 = (*(_BYTE *)(i + 135206) & 0x3F) + 33; // 这个结果包含了第i+2个字符的低6位}if ( i <= 15 ){v4 = v13++;*v4 = (*(_BYTE *)(i + 135204) >> 2) + 33; // 通过这个得出一个字符中高6位的值v5 = v13++;if ( i == 15 ){*v5 = ((16 * MEMORY[0x21033]) & 0x30) + 33;// ((16**(byte*)(i+0x21024))&0x30)+0x21 通过这个计算一个字符中最低两位的值v6 = v13++;*v6 = 32;}else{*v5 = ((16 * *(_BYTE *)(i + 135204)) & 0x30 | (*(_BYTE *)(i + 135205) >> 4)) + 33;v7 = v13++;*v7 = ((4 * *(_BYTE *)(i + 135205)) & 0x3C) + 33;}v8 = v13++;*v8 = 32;}v9 = v13++;*v9 = 0;for ( i = 0; i <= 23 && v10[i] == v11[i]; ++i );JUMPOUT(0x400);}
from unicorn import *from unicorn.x86_const import *from unicorn.arm_const import *from unicorn.mips_const import *from capstone import *with open('Arm', 'rb') as file:ARM_CODE=file.read()class UnidbgArm:def __init__(self):# x32程序mu = Uc(UC_ARCH_ARM, UC_MODE_ARM)0x200000)mu.mem_map(0x10000,0x1000)mu.mem_write(0x200000,ARM_CODE)mu.mem_map(0x20000,0x10000)#输入假的数据mu.reg_write(UC_ARM_REG_SP,0x11000)self.hook_code)=mu# 反汇编引擎= Cs(CS_ARCH_ARM,UC_MODE_ARM)def hook_code(self, mu,address, size, data):if address==0x200010 or address==0x200058:v5=mu.reg_read(UC_ARM_REG_R3)=15mu.reg_write(UC_ARM_REG_R3,v5)elif address==0x200018:v5 = mu.reg_read(UC_ARM_REG_R3)v5 ^= 0x6Fv5)elif address==0x200020 or address==0x200040:v5 = mu.reg_read(UC_ARM_REG_R3)v5 -=12v5)elif address==0x200028:v5 = mu.reg_read(UC_ARM_REG_R3)v5 ^= 0x12v5)elif address==0x200030 or address==0x200070:v5 = mu.reg_read(UC_ARM_REG_R3)v5 -=5v5)elif address==0x200038:v5 = mu.reg_read(UC_ARM_REG_R3)v5 += 33v5)elif address==0x200048:v5 = mu.reg_read(UC_ARM_REG_R3)v5 ^= 0xDv5)elif address==0x200050:v5 = mu.reg_read(UC_ARM_REG_R3)v5 -=3v5)elif address == 0x200060:v5 = mu.reg_read(UC_ARM_REG_R3)v5 ^= 0x68v5)elif address == 0x200068:v5 = mu.reg_read(UC_ARM_REG_R3)v5 ^= 0xAv5)elif address == 0x200078:v5 = mu.reg_read(UC_ARM_REG_R3)v5 -= 33v5)elif address == 0x200080:v5 = mu.reg_read(UC_ARM_REG_R3)v5 +=48v5)elif address == 0x200088:v5 = mu.reg_read(UC_ARM_REG_R3)v5 ^=0x18v5)elif address == 0x200090:v5 = mu.reg_read(UC_ARM_REG_R3)v5 +=2v5)elif address == 0x200098:v5 = mu.reg_read(UC_ARM_REG_R3)v5 -=16v5)elif address == 0x2000A0:v5 = mu.reg_read(UC_ARM_REG_R3)v5 ^=0x1Bv5)elif address == 0x2000A8:v5 = mu.reg_read(UC_ARM_REG_R3)v5 +=6v5)elif address == 0x2000B0:v5 = mu.reg_read(UC_ARM_REG_R3)v5 ^=0x13v5)# if(mu.reg_read(UC_ARM_REG_R3)>=32 and mu.reg_read(UC_ARM_REG_R3)<=126):# print(chr(mu.reg_read(UC_ARM_REG_R3)))# else::0x%x r2:0x%x r1:0x%x r0:0x%x"%(mu.reg_read(UC_ARM_REG_R3),mu.reg_read(UC_ARM_REG_R2),mu.reg_read(UC_ARM_REG_R1),mu.reg_read(UC_ARM_REG_R0)))disasm = self.md.disasm(mu.mem_read(address, size), address)for i in disasm::t%st%s" %(i.address,i.mnemonic,i.op_str))def start(self):try:0x200400)print(self.mu.reg_read(66))except:passif __name__ == '__main__':#UnidbgMips().start()UnidbgArm().start()
发现这里有一些常量存到了一个连续的地址中，对应IDA就是以下一些字符：
但是他在程序中注册了一个hook回调，我们看一下回调里干了啥：
对v5进行了一些操作，而v5对应的就是代码里的r3寄存器，说明该hook代码将IDA中识别的字符串进行了改变，手动提取得到：
unsigned char res[] = {0x38,0x57,0x3A,0x42,0x39,0x57,0x52,0x4F,0x3A,0x56,0x5E,0x4A,0x39,0x37,0x5A,0x48,0x3E,0x37,0x26,0x48,0x3A,0x31};
他将我们输入的字符进行了一些拆分，然后存起来。通过自己写的unicorn调试输出一些寄存器的值，得到函数最后将拆分得到的结果值和上面的那串res里的值进行比对，直接写脚本求解：
#include<iostream>#include<Windows.h>using namespace std;unsigned char flag[50] = { 0 };unsigned int key[] = {0x0,0xf26b8303,0xe13b70f7,0x1350f3f4,0xc79a971f,0x35f1141c,0x26a1e7e8,0xd4ca64eb,0x8ad958cf,0x78b2dbcc,0x6be22838,0x9989ab3b,0x4d43cfd0,0xbf284cd3,0xac78bf27,0x5e133c24,0x105ec76f,0xe235446c,0xf165b798,0x30e349b,0xd7c45070,0x25afd373,0x36ff2087,0xc494a384,0x9a879fa0,0x68ec1ca3,0x7bbcef57,0x89d76c54,0x5d1d08bf,0xaf768bbc,0xbc267848,0x4e4dfb4b,0x20bd8ede,0xd2d60ddd,0xc186fe29,0x33ed7d2a,0xe72719c1,0x154c9ac2,0x61c6936,0xf477ea35,0xaa64d611,0x580f5512,0x4b5fa6e6,0xb93425e5,0x6dfe410e,0x9f95c20d,0x8cc531f9,0x7eaeb2fa,0x30e349b1,0xc288cab2,0xd1d83946,0x23b3ba45,0xf779deae,0x5125dad,0x1642ae59,0xe4292d5a,0xba3a117e,0x4851927d,0x5b016189,0xa96ae28a,0x7da08661,0x8fcb0562,0x9c9bf696,0x6ef07595,0x417b1dbc,0xb3109ebf,0xa0406d4b,0x522bee48,0x86e18aa3,0x748a09a0,0x67dafa54,0x95b17957,0xcba24573,0x39c9c670,0x2a993584,0xd8f2b687,0xc38d26c,0xfe53516f,0xed03a29b,0x1f682198,0x5125dad3,0xa34e59d0,0xb01eaa24,0x42752927,0x96bf4dcc,0x64d4cecf,0x77843d3b,0x85efbe38,0xdbfc821c,0x2997011f,0x3ac7f2eb,0xc8ac71e8,0x1c661503,0xee0d9600,0xfd5d65f4,0xf36e6f7,0x61c69362,0x93ad1061,0x80fde395,0x72966096,0xa65c047d,0x5437877e,0x4767748a,0xb50cf789,0xeb1fcbad,0x197448ae,0xa24bb5a,0xf84f3859,0x2c855cb2,0xdeeedfb1,0xcdbe2c45,0x3fd5af46,0x7198540d,0x83f3d70e,0x90a324fa,0x62c8a7f9,0xb602c312,0x44694011,0x5739b3e5,0xa55230e6,0xfb410cc2,0x92a8fc1,0x1a7a7c35,0xe811ff36,0x3cdb9bdd,0xceb018de,0xdde0eb2a,0x2f8b6829,0x82f63b78,0x709db87b,0x63cd4b8f,0x91a6c88c,0x456cac67,0xb7072f64,0xa457dc90,0x563c5f93,0x82f63b7,0xfa44e0b4,0xe9141340,0x1b7f9043,0xcfb5f4a8,0x3dde77ab,0x2e8e845f,0xdce5075c,0x92a8fc17,0x60c37f14,0x73938ce0,0x81f80fe3,0x55326b08,0xa759e80b,0xb4091bff,0x466298fc,0x1871a4d8,0xea1a27db,0xf94ad42f,0xb21572c,0xdfeb33c7,0x2d80b0c4,0x3ed04330,0xccbbc033,0xa24bb5a6,0x502036a5,0x4370c551,0xb11b4652,0x65d122b9,0x97baa1ba,0x84ea524e,0x7681d14d,0x2892ed69,0xdaf96e6a,0xc9a99d9e,0x3bc21e9d,0xef087a76,0x1d63f975,0xe330a81,0xfc588982,0xb21572c9,0x407ef1ca,0x532e023e,0xa145813d,0x758fe5d6,0x87e466d5,0x94b49521,0x66df1622,0x38cc2a06,0xcaa7a905,0xd9f75af1,0x2b9cd9f2,0xff56bd19,0xd3d3e1a,0x1e6dcdee,0xec064eed,0xc38d26c4,0x31e6a5c7,0x22b65633,0xd0ddd530,0x417b1db,0xf67c32d8,0xe52cc12c,0x1747422f,0x49547e0b,0xbb3ffd08,0xa86f0efc,0x5a048dff,0x8ecee914,0x7ca56a17,0x6ff599e3,0x9d9e1ae0,0xd3d3e1ab,0x21b862a8,0x32e8915c,0xc083125f,0x144976b4,0xe622f5b7,0xf5720643,0x7198540,0x590ab964,0xab613a67,0xb831c993,0x4a5a4a90,0x9e902e7b,0x6cfbad78,0x7fab5e8c,0x8dc0dd8f,0xe330a81a,0x115b2b19,0x20bd8ed,0xf0605bee,0x24aa3f05,0xd6c1bc06,0xc5914ff2,0x37faccf1,0x69e9f0d5,0x9b8273d6,0x88d28022,0x7ab90321,0xae7367ca,0x5c18e4c9,0x4f48173d,0xbd23943e,0xf36e6f75,0x105ec76,0x12551f82,0xe03e9c81,0x34f4f86a,0xc69f7b69,0xd5cf889d,0x27a40b9e,0x79b737ba,0x8bdcb4b9,0x988c474d,0x6ae7c44e,0xbe2da0a5,0x4c4623a6,0x5f16d052,0xad7d5351};void getFirstHalfFlag(){memset(flag, 0, 50);unsigned int res[] = {0x2F2E,0x282A,0x2C42,0x2A8A,0x13E0,0x36D4};unsigned char key[] = "zjgcjy";for (int i = 0; i < 6; i++) {flag[i] = res[i] / key[i];}printf("%srn", flag);unsigned char key1[] = {0xFC,0x1,0xF3,0xFA,0xE,0xBB,0x3E,0x0};unsigned char key2[] = {0xC2,0xC3,0xD7,0xC4,0xDA,0xA5,0xA0,0xBE};for (int i = 0; i < 8; i++) {for (unsigned char a = 32; a <= 126; a++) {for (unsigned char b = 32; b <= 126; b++) {unsigned char res1 = a - b;unsigned char res2 = a + b;if (res1 == key1[i] && res2 == key2[i]) {flag[6 + i] = a;flag[14 + i] = b;break;}}}}printf("%srn", flag);}void getLastHalfFlag(){//直接爆破 爆出来是 when/*unsigned int v1;DWORD res = 0xCAFABCBC;res = ~res;for (DWORD i = 0x32323232; i <= 0x7E7E7E7E; i++) {v1 = -1;unsigned char *cRes = (unsigned char*)&i;for (int j = 0; j < 4; j++) {unsigned char value = cRes[j] ^ v1;v1 = ((v1 >> 8) ^ key[value]);}if (res == v1) {printf("%xrn", i);break;}}*/memcpy(&flag[22], "when", 4);printf("%srn", flag);unsigned char res[] = {0x38,0x57,0x3A,0x42,0x39,0x57,0x52,0x4F,0x3A,0x56,0x5E,0x4A,0x39,0x37,0x5A,0x48,0x3E,0x37,0x26,0x48,0x3A,0x31};unsigned char chr1 = 0;unsigned char chr2 = 0;unsigned char chr3 = 0;int total = 26;for (int i = 0; i < 18; i += 4) {chr1 = (res[i] - 0x21) << 2;chr1 = ((res[i + 1] - 0x21) >> 4) | chr1;chr2 = ((res[i + 1] - 0x21) << 4);chr2 = ((res[i + 2] - 0x21) >>2) | chr2;chr3 = res[i + 3] - 0x21;chr3 = ((res[i + 2] - 0x21) << 6) | chr3;flag[total++] = chr1;flag[total++] = chr2;flag[total++] = chr3;}chr1= (res[20] - 0x21) << 2;chr1 = chr1 | ((res[21] - 0x21) >> 4);flag[total] = chr1;printf("%srn", flag);}int main(){getFirstHalfFlag();getLastHalfFlag();return 0;}
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