2024.6.29 某行业赛 一道 Crypto+Misc 希尔密码
Hill Cipher(不知道题目叫什么名字)
下载题目附件后打开看到
![](https://lov2.netlify.app/post-images/1719651423244.png)
拖到 010 Editor 提示报错,注意到文件末尾存在字符串,且为三的倍数
同时结合图片名为 hill.png 以及图片中数字的排列,推导可能是 Hill Cipher
Exploit
SageMath's Code
# https://doc.sagemath.org/html/en/reference/cryptography/sage/crypto/classical.html#sage.crypto.classical.HillCryptosystem
from sage.all import *
cryptoflag = 'CLYCOEXMAYHD'
# row major
enc_key = Matrix([
[
2,4,5
],
[
9,2,1
],
[
3,17,7
]
])
# transpose
enc_key = enc_key.transpose()
S = AlphabeticStrings()
H = HillCryptosystem(S, 3)
R = IntegerModRing(26)
M = MatrixSpace(R, 3, 3)
A = M(enc_key)
e = H(A)
# enc = e(S("LAMAISONBLANCHE"))
# print(enc)
# print(type(enc))
print(H.deciphering(A, S(cryptoflag)))
Output:
THISISHILLOK