XCTF-Reverse：open-source

題目地址：https://adworld.xctf.org.cn/task/answer?type=reverse&number=4&grade=0&id=5076&page=1

拖延和等待是世界上最容易壓垮一個人鬥志的東西

工具：C語言編輯器 、python（指令碼）
知識：對C語言程式碼解讀

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

int main(int argc, char *argv[]) {
    if (argc != 4) {
    	printf("what?\n");
    	exit(1); // 功 能: 關閉所有檔案，終止正在執行的程式。
    }

    unsigned int first = atoi(argv[1]);
    if (first != 0xcafe) {
    	printf("you are wrong, sorry.\n");
    	exit(2);
    }

    unsigned int second = atoi(argv[2]);
    if (second % 5 == 3 || second % 17 != 8) {
    	printf("ha, you won't get it!\n");
    	exit(3);
    }

    if (strcmp("h4cky0u", argv[3])) {
    	printf("so close, dude!\n");
    	exit(4);
    }

    printf("Brr wrrr grr\n");

    unsigned int hash = first * 31337 + (second % 17) * 11 + strlen(argv[3]) - 1615810207;

    printf("Get your key: ");
    printf("%x\n", hash);
    return 0;
}

flag為c0ffee