黑客信息网：ctf密码学之四方密码解密
import collections
import re
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matrix='ABCDEFGHIJKLMNOPRSTUVWXYZ'
pla='abcdefghijklmnoprstuvwxyz'
key1='[SECURITY]'
key2='[INFORMATION]'
key1=''.join(collections.OrderedDict.fromkeys(key1))
key2=''.join(collections.OrderedDict.fromkeys(key2))
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matrix1=re.sub('[\[\]]','',key1) + re.sub(key1,'',matrix)
matrix2=re.sub('[\[\]]','',key2) + re.sub(key2,'',matrix)
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matrix_list1=[]
matrix_list2=[]
pla_list=[]
for i in range(0,len(matrix1),5):
matrix_list1.append(list(matrix1[i:i+5]))
#print matrix_list1
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for i in range(0,len(matrix2),5):
matrix_list2.append(list(matrix2[i:i+5]))
#print matrix_list2
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for i in range(0,len(pla),5):
pla_list.append(list(pla[i:i+5]))
#print pla_list
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#查询两个密文字母位置
def find_index1(x):
for i in range(len(matrix_list1)):
for j in range(len(matrix_list1[i])):
if matrix_list1[i][j]==x:
return i,j
def find_index2(y):
for k in range(len(matrix_list2)):
for l in range(len(matrix_list2[k])):
if matrix_list2[k][l]==y:
return k,l
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def gen_pla(letter):
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#两个子母中第一个字母位置
first=find_index1(letter[0])
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#两个子母中第二个字母位置
second=find_index2(letter[1])
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pla=''
pla +=pla_list[first[0]][second[1]]
pla +=pla_list[second[0]][first[1]]
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return pla
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def main():
cip='ZHNJINHOOPCFCUKTLJ'
pla=''
for i in range(0,len(cip),2):
pla +=gen_pla(cip[i:i+2])
print (pla)
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if __name__=='__main__':
main()
