The Foreign Student

Tarbiat Modares University has a foreign student. His name is Zedmondo. He has a very shady character. He always walks alone, eats alone, and never talks much.There are some rumors about him. Some people say he is a genius sociopath; some say he is just too self-involved. But one thing is obvious; he has a secret.Once, one of the students heard that he was talking about receiving some important documents via a private email. Maybe if we find his email, we can learn about his secret.*

题目是要我们找一个叫Zedmondo的大学生的private email

首先,用Google搜索Zedmondo Tarbiat Modares University,找到这个人的Linkedin主页

除了一个Github链接外(https://github.com/ZedZini),没有什么其他有价值的信息

浏览Github上的仓库,结合题目中的he has a secret.,一个仓库https://github.com/ZedZini/secretkey的README引起了我的注意.

# secretkey
It is a public key. Not really a secret, right?!

与README一起的还有一个PGP公钥文件:

-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: Keybase OpenPGP v1.0.0
Comment: https://keybase.io/crypto

xsFNBGAqSQ8BEADZtFG6grS2QP9afsA7SmT85TpxcSmG5LGLmSHKgI47ZwS+dPrO
SzChR0Jt3vI7BjA3WVlxQp94XTqRqFrjtJkS2I3nO3I94jhLu0AwfoiskKzyl+tQ
...
-----END PGP PUBLIC KEY BLOCK-----

访问https://keybase.io/crypto,发现网站上已经给出了使用说明:

Using the Keybase command line app
keybase pgp encrypt -m "message" [them]
With GPG or another PGP program
You may import from Keybase to GPG easily and then perform whatever cryptographic actions you want.

# using curl
curl https://keybase.io/[them]/key.asc | gpg --import

# using `keybase pgp pull` which
# imports to GPG key chain for you
keybase follow [them]
keybase pgp pull [them]

参照使用说明:

curl https://raw.githubusercontent.com/ZedZini/secretkey/main/0xEB0B6528-pub.asc | gpg --import

  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0  
gpg: 目录‘/Users/zhaoqi219/.gnupg’已创建
gpg: 钥匙箱‘/Users/zhaoqi219/.gnupg/pubring.kbx’已创建
100  6139  100  6139    0     0   4494      0  0:00:01  0:00:01 --:--:--  4490
gpg: /Users/zhaoqi219/.gnupg/trustdb.gpg：建立了信任度数据库
gpg: 密钥 586DD615EB0B6528：公钥 “Zedmondo Zaberini (Nothing to say...) <[email protected]>” 已导入
gpg: 处理的总数：1
gpg:               已导入：1

flag: TMUCTF{[email protected]}

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The Foreign Student