Binary Ninja MCP

#include <stdio.h> #include <stdint.h> #include <string.h> static inline uint8_t rol8(uint8_t x, unsigned r) { r &= 7; return (uint8_t)(((x << r) | (x >> (8 - r))) & 0xFF); } // 對輸入做位移 + 滾動 XOR 的目標結果（作者預先計算好） // Shift + rolling XOR applied to the input with the target result static const uint8_t EXPECTED[32] = { 0x1c, 0x2e, 0x74, 0xd0, 0x52, 0xe2, 0xd4, 0x86, 0x0e, 0xa6, 0xec, 0x39, 0x75, 0x21, 0x17, 0x8d, 0x13, 0x68, 0x88, 0xe2, 0x00, 0xa0, 0x11, 0x17, 0x3f, 0x60, 0x90, 0x51, 0xb3, 0x68, 0x00, 0x02 }; int main(void) { char buf[256]; puts("Enter flag:"); if (!fgets(buf, sizeof(buf), stdin)) { puts("Read error"); return 1; } // 去除換行 size_t n = strcspn(buf, "\r\n"); buf[n] = '\0'; // 簡單長度與格式檢查（避免垃圾輸入） if (n != 32 || strncmp(buf, "FLAG{", 5) != 0 || buf[n-1] != '}') { puts("Nope"); return 1; } // 轉換並比對 uint8_t acc[32]; for (size_t i = 0; i < n; i++) { uint8_t b = (uint8_t)buf[i]; b ^= (uint8_t)(0x5A + i); b = rol8(b, (unsigned)(i & 7)); acc[i] = b; } if (memcmp(acc, EXPECTED, 32) == 0) { puts("Correct! 🎉"); return 0; } else { puts("Nope"); return 1; } }