This year is too much food. I don't know whether it is difficult or I have cooked my own food. I don't want to write about what I can't do. I just say two questions I have done and leave a record.
1. Sign in
Very simple 8 multiple-choice questions, all right, then give it to the flag, and copy it out of the review element
2. Minesweeping (misc)
One python mine sweeping, 16x30, 99 mines in the difficult mode, 10 passes will be given to the flag
16x30, 99 thunder mode. It's almost impossible to win 10 of this thing by hand. Win now defaults to not carrying minesweeping. I don't know how many skilled minesweeping masters can handle difficult minesweepingThe vertical axis of this thing is the x axis, and the horizontal axis is the y axis. The author either intentionally or has a hole in his head
The idea is to find a ready-made mine sweeping algorithm, and let the machine help you sweep 10 rounds of customs clearance to get the flag. I haven't realized this, and the idea should be no problem.
At first, I thought it was base64. I found the base64 website of the custom dictionary onlinehttp://web.chacuo.net/netbasex
This website is very easy to use, but the dictionary ciphertext is input, and the result is garbled. After careful counting, the dictionary is 62 bits, which should be a rare base62 code. Unfortunately, this website is very easy to use and does not support the custom dictionary mode of base62
I started to find the online parsing website base62 that supports custom dictionary on the Internet. I found many websites, but none of them support custom dictionary (true fw)
I want to try the ctf artifacthttps://github.com/mufeedvh/basecrack
The company network is not very good. It took a long time to install this device, but after installing it, I found that this device does not support custom dictionaries. I just crashed. This is also called a magic tool???
Later, I began to find base62 codes that can customize dictionaries. I also found a lot of codes. After trying, many codes can only encode and decode integers to results???
The original base62 is widely used for URL short link coding. Several examples
I started to find a PHP code. The dictionary ciphertext was filled in and solved to be a string of integers, which directly fooled me
Finally, I understand that base62 has two modes: int and string. The common environment uses its int mode. Generally, string has base64. Who uses base62
So string is a niche requirement of base62.
I found a java code later,https://github.com/seruco/base62
Anyway, at least this code can be used. You can directly copy the code to your own blank project without importing it from readme
Change the default code table
Input ciphertext, a shuttle
The flag came out
It was annoying that the deadline for submission was 5:00 p.m., and the broken thing lasted two hours, and then GG exceeded the time limit
4. Summary
This year's Netting Cup is really unfriendly to chicken dishes. For example, the question "base62" was released at what time in the afternoon. In the morning, I was upset by my anal minesweeping. I had lunch at noon, took a nap, and held a meeting in the afternoon. When I opened the meeting, I found that there was a simple misc. More than 100 teams solved it. It was not difficult to get started. Why not release it in the morning,Xuanwu Group are all kids who have to go to work. Who has time to focus on the topic all day? In short, they are very angry. Hum
