ctfshow baby杯 MISC 不问天 WriteUp

题目

附件下载下来 拖进010梭哈一下，，没啥特别的   foremost走一遭

掏出一个封面图片跟一个加密的zip文件

前面用肉眼啃  感觉这小点点有点特别 中间有一行白色的小点不太一样

不知道咋处理 丢进stegSlove 

胡乱用眼睛啃出来有内容：password：BVnumber（不是正解  瞎猫碰上死耗子

赛后参考了套宝的wp  音频文件末尾有一串base64考虑近邻法（说实话我也不知道为啥 知识盲区

ps打开   图像选项中选择图像大小 用邻近法把图像缩小十倍  就能得到清楚的密码了（具体参考套宝的wp  反正我不会（bushi）

在题目提示中得到BV号

打开压缩包  得到一份txt文件 好像是歌词

观察发现 前半部分歌词排序有规律  中间还夹带了空格

然后这里就卡住了，，，最后套宝给了hint  观察空格长度

把空格替换成x  每一行的长度刚好都是7

考虑二进制转ASCII  尝试手撸前两行 得到f跟l  得  大胆手撸（当时太急  真不知道想脚本了

梭哈完

flag{liangyuan_BuWenTian_HaoShi_shurenjian!}

附上套宝的脚本

s = ["1100110","1101100","1100001","1100111","1111011","1101100","1101001","1100001","1101110","1100111","1111001","1110101","1100001","1101110","1011111","1000010","1110101","1010111","1100101","1101110","1010100","1101001","1100001","1101110","1011111","1001000","1100001","1101111","1010011","1101000","1101001","1011111","1110011","1101000","1110101","1110010","1100101","1101110","1101010","1101001","1100001","1101110","100001","1111101"]flag = ''
f = [0]*len(s)
for i in range(len(s)):f[i] = s[i].zfill(8)
print(f)
for j in range(len(f)):flag += chr(int(f[j],2))
print(flag)

 拿下  我爱套宝