1.解题背景

希尔密码的直观数学原理- Wikipedia

step1:字母表

   首先根据A=1的提示构造出字母表
  ['z','a','b','c','d','e','f','g','h',
  'i','j','k','l','m','n','o','p','q',
  'r','s','t','u','v','w','x','y']

step2:密文

  密文:plgtgbqhm

step3:密钥

根据棋盘获得3*3的密钥
	[[1,2,3],
	[0,1,4],
	[5,6,0]]    

2.解题脚本

import numpy as np
table=['z','a','b','c','d','e','f','g','h',
       'i','j','k','l','m','n','o','p','q',
       'r','s','t','u','v','w','x','y']
key_inv=np.matrix(np.array([[1,2,3],[0,1,4],[5,6,0]])).I%26
result=key_inv*np.array([[16,20,17],
                [12,7,8],
                [7,2,13]])%26
str=''
resulttable=[]
for i in range(result.shape[0]):
    for j in range(result.shape[1]):
        resulttable.append(round(result.T[i,j]))
for i in range(9):
    str+=table[resulttable[i]]
print("bugku{"+str+'}')
#bugku{whatahill}

3.flag

bugku{whatahill}