nctf

grand2025-03-252025-03-24

x1Login

private final void checkSecutity() {
       if (Secure.checkDebug()) {
           Toast.makeText(this, "Debugger Detected!", 0).show();
           exit();
       }
       if (Secure.checkRoot()) {
           Toast.makeText(this, "Root Detected!", 0).show();
           exit();
       }
   }

上来就是root的检测和调试的检测好在java层不然要炸缸 mt管理器去除一下调用就行

接着看

查看so

直接上frida看看怎么个事

 Java.perform(function (){
     let DecStr = Java.use("com.nctf.simplelogin.DecStr");
    DecStr["get"].implementation = function (str) {
    console.log(`DecStr.get is called: str=${str}`);
    str="Exv3nhr5BNW0axn3aNz/DNv9C3q0wxj/Exe="
    let result = this["get"](str);
    console.log(`DecStr.get result=${result}`);
    return result;
};
})

加载了check 这东西说白了就是字符串加密

1	X1c@dM1n1$t

获取到用户名

进入assest文件夹

假的elf 抹了

再次去解密一下是md5

将用户名md5传入密码的校验方法中

在这里我们发现loaddex函数

直接进另一个so看看

动态注册了一个方法

不断跟进找到这东西看看key是什么

1	7d53ecd36a43d3d2 37e7dd633dcf8497

分析加密算法是3des 中间的是解密

1	NCTF{X1c@dM1n1$t_SafePWD~5y$x?YM+5U05Gm6=}

gogo

我拿ida9做的符号自动优化了

判断长度

SafeProgram

sm4

改了sbox没发现搞得我心态爆炸

#include <stdio.h>
#include <stdint.h>
#include <string.h>

#define SM4_ENCRYPT 1
#define SM4_DECRYPT 0

// SM4 S盒
static const uint8_t Sbox[256] = {
    0xD1, 0x90, 0xE9, 0xFE, 0xCC, 0xE1, 0x3D, 0xB7, 0x16, 0xB6, 
  0x14, 0xC2, 0x28, 0xFB, 0x2C, 0x05, 0x2B, 0x67, 0x9A, 0x76, 
  0x2A, 0xBE, 0x04, 0xC3, 0xAA, 0x44, 0x13, 0x26, 0x49, 0x86, 
  0x06, 0x99, 0x9C, 0x42, 0x50, 0xF4, 0x91, 0xEF, 0x98, 0x7A, 
  0x33, 0x54, 0x0B, 0x43, 0xED, 0xCF, 0xAC, 0x62, 0xE4, 0xB3, 
  0x17, 0xA9, 0x1C, 0x08, 0xE8, 0x95, 0x80, 0xDF, 0x94, 0xFA, 
  0x75, 0x8F, 0x3F, 0xA6, 0x47, 0x07, 0xA7, 0x4F, 0xF3, 0x73, 
  0x71, 0xBA, 0x83, 0x59, 0x3C, 0x19, 0xE6, 0x85, 0xD6, 0xA8, 
  0x68, 0x6B, 0x81, 0xB2, 0xFC, 0x64, 0xDA, 0x8B, 0xF8, 0xEB, 
  0x0F, 0x4B, 0x70, 0x56, 0x9D, 0x35, 0x1E, 0x24, 0x0E, 0x78, 
  0x63, 0x58, 0x9F, 0xA2, 0x25, 0x22, 0x7C, 0x3B, 0x01, 0x21, 
  0xC9, 0x87, 0xD4, 0x00, 0x46, 0x57, 0x5E, 0xD3, 0x27, 0x52, 
  0x4C, 0x36, 0x02, 0xE7, 0xA0, 0xC4, 0xC8, 0x9E, 0xEA, 0xBF, 
  0x8A, 0xD2, 0x40, 0xC7, 0x38, 0xB5, 0xA3, 0xF7, 0xF2, 0xCE, 
  0xF9, 0x61, 0x15, 0xA1, 0xE0, 0xAE, 0x5D, 0xA4, 0x9B, 0x34, 
  0x1A, 0x55, 0xAD, 0x93, 0x32, 0x30, 0xF5, 0x8C, 0xB1, 0xE3, 
  0x1D, 0xF6, 0xE2, 0x2E, 0x82, 0x66, 0xCA, 0x60, 0xC0, 0x29, 
  0x23, 0xAB, 0x0D, 0x53, 0x4E, 0x6F, 0xD5, 0xDB, 0x37, 0x45, 
  0xDE, 0xFD, 0x8E, 0x2F, 0x03, 0xFF, 0x6A, 0x72, 0x6D, 0x6C, 
  0x5B, 0x51, 0x8D, 0x1B, 0xAF, 0x92, 0xBB, 0xDD, 0xBC, 0x7F, 
  0x11, 0xD9, 0x5C, 0x41, 0x1F, 0x10, 0x5A, 0xD8, 0x0A, 0xC1, 
  0x31, 0x88, 0xA5, 0xCD, 0x7B, 0xBD, 0x2D, 0x74, 0xD0, 0x12, 
  0xB8, 0xE5, 0xB4, 0xB0, 0x89, 0x69, 0x97, 0x4A, 0x0C, 0x96, 
  0x77, 0x7E, 0x65, 0xB9, 0xF1, 0x09, 0xC5, 0x6E, 0xC6, 0x84, 
  0x18, 0xF0, 0x7D, 0xEC, 0x3A, 0xDC, 0x4D, 0x20, 0x79, 0xEE, 
  0x5F, 0x3E, 0xD7, 0xCB, 0x39, 0x48
};

// 系统参数 FK
static const uint32_t FK[4] = {
    0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc
};

// 固定参数 CK
static const uint32_t CK[32] = {
    0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269,
    0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9,
    0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249,
    0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9,
    0xc0c7ced5, 0xdce3eaf1, 0xf8ff060d, 0x141b2229,
    0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299,
    0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209,
    0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279
};

// 循环左移函数
uint32_t rotl(uint32_t x, int n) {
    return (x << n) | (x >> (32 - n));
}

// 非线性变换 τ（S盒替换）
uint32_t tau(uint32_t A) {
    uint32_t a0 = (A >> 24) & 0xff;
    uint32_t a1 = (A >> 16) & 0xff;
    uint32_t a2 = (A >> 8) & 0xff;
    uint32_t a3 = A & 0xff;
    uint32_t b0 = Sbox[a0];
    uint32_t b1 = Sbox[a1];
    uint32_t b2 = Sbox[a2];
    uint32_t b3 = Sbox[a3];
    return (b0 << 24) | (b1 << 16) | (b2 << 8) | b3;
}

// 线性变换 L（用于加密/解密轮函数）
uint32_t L(uint32_t B) {
    return B ^ rotl(B, 2) ^ rotl(B, 10) ^ rotl(B, 18) ^ rotl(B, 24);
}

// 线性变换 L'（用于密钥扩展）
uint32_t L_prime(uint32_t B) {
    return B ^ rotl(B, 13) ^ rotl(B, 23);
}

// 密钥扩展，生成32个轮密钥
void sm4_key_schedule(const uint8_t key[16], uint32_t rk[32]) {
    uint32_t K[36];
    int i;
    // 将用户密钥转换为 32 位整数，并与 FK 异或
    for (i = 0; i < 4; i++) {
        K[i] = ((uint32_t)key[4*i] << 24) |
               ((uint32_t)key[4*i+1] << 16) |
               ((uint32_t)key[4*i+2] << 8) |
               ((uint32_t)key[4*i+3]);
        K[i] ^= FK[i];
    }
    // 生成32个轮密钥
    for (i = 0; i < 32; i++) {
        uint32_t temp = K[i+1] ^ K[i+2] ^ K[i+3] ^ CK[i];
        temp = tau(temp);
        temp = L_prime(temp);
        K[i+4] = K[i] ^ temp;
        rk[i] = K[i+4];
    }
}

// SM4 单轮加密/解密操作
void sm4_crypt(const uint8_t in[16], uint8_t out[16], const uint32_t rk[32]) {
    uint32_t X[36];
    int i;
    // 将输入明文（或密文）分成4个 32 位字
    for (i = 0; i < 4; i++) {
        X[i] = ((uint32_t)in[4*i] << 24) |
               ((uint32_t)in[4*i+1] << 16) |
               ((uint32_t)in[4*i+2] << 8) |
               ((uint32_t)in[4*i+3]);
    }
    // 进行32轮迭代
    for (i = 0; i < 32; i++) {
        uint32_t temp = X[i+1] ^ X[i+2] ^ X[i+3] ^ rk[i];
        temp = tau(temp);
        temp = L(temp);
        X[i+4] = X[i] ^ temp;
    }
    // 结果为 X35, X34, X33, X32（倒序输出）
    for (i = 0; i < 4; i++) {
        uint32_t x = X[35 - i];
        out[4*i]   = (uint8_t)(x >> 24);
        out[4*i+1] = (uint8_t)(x >> 16);
        out[4*i+2] = (uint8_t)(x >> 8);
        out[4*i+3] = (uint8_t)(x);
    }
}

int main() {
    // 示例密钥（16字节）
    uint8_t key[16] = {
        0x4E, 0x43, 0x54, 0x46, 0x32, 0x34, 0x6E, 0x63, 0x74, 0x66, 
        0x4E, 0x43, 0x54, 0x46, 0x32, 0x34
    };

    // 示例密文（16字节），请将此处替换为实际密文
    uint8_t ciphertext[16] = {
        0x14, 0x5B, 0xA6, 0x2A, 
        0xA8, 0x05, 0xA5, 0xF3, 0x76, 0xBE, 0xC9, 0x01, 0xF9, 0x36, 
        0x7B, 0x46
    };

    uint8_t plaintext[16];
    uint32_t rk[32];

    // 生成轮密钥
    sm4_key_schedule(key, rk);

    // 解密时需要将轮密钥逆序使用
    uint32_t rk_dec[32];
    for (int i = 0; i < 32; i++) {
        rk_dec[i] = rk[31 - i];
    }

    // 进行解密运算
    sm4_crypt(ciphertext, plaintext, rk_dec);

    // 输出解密后的明文
    
    for (int i = 0; i < 16; i++) {
        printf("%02x ", plaintext[i]);
    }
    printf("\n");

    return 0;
}