10-加密-BugkuCTF之托马斯.杰斐逊

一，题目--托马斯.杰斐逊

1： 

二，转轮密码

• 1，首先根据秘钥进行每行顺序的调整
  eg. 第一行是原来的第二行，第二行是原来的第五行
  以此类推得到：

KPBELNACZDTRXMJQOYHGVSFUWI
IHFRLABEUOTSGJVDKCPMNZQWXY
ZWAXJGDLUBVIQHKYPNTCRMOSFE
BDMAIZVRNSJUWFHTEQGYXPLOCK
AMKGHIWPNYCJBFZDRUSLOQXVET
RPLNDVHGFCUKTEBSXQYIZMJWAO
QWATDSRFHENYVUBMCOIKZGJXPL
GWTHSPYBXIZULVKMRAFDCEONJQ
NOZUTWDCVRJLXKISEFAPMYGHBQ
XPHKZGJTDSENYVUBMLAOIRFCQW
WABMCXPLTDSRJQZGOIKFHENYVU
BMCSRFHLTDENQWAOXPYVUIKZGJ
XPLTDAOIKFZGHENYSRUBMCQWVJ
TDSWAYXPLVUBOIKZGJRFHENMCQ

• 2 根据密文调整每行字符串
  eg.密文第一个字符H，第一行则变为：HGVSFUWIKPBELNACZDTRXMJQOY
  密文第二个字符C，第二行则变为：CPMNZQWXYIHFRLABEUOTSGJVDK
  以此类推得到：

HGVSFUWIKPBELNACZDTRXMJQOY
CPMNZQWXYIHFRLABEUOTSGJVDK
BVIQHKYPNTCRMOSFEZWAXJGDLU
TEQGYXPLOCKBDMAIZVRNSJUWFH
SLOQXVETAMKGHIWPNYCJBFZDRU
XQYIZMJWAORPLNDVHGFCUKTEBS
WATDSRFHENYVUBMCOIKZGJXPLQ
CEONJQGWTHSPYBXIZULVKMRAFD
RJLXKISEFAPMYGHBQNOZUTWDCV
QWXPHKZGJTDSENYVUBMLAOIRFC
GOIKFHENYVUWABMCXPLTDSRJQZ
LTDENQWAOXPYVUIKZGJBMCSRFH
ENYSRUBMCQWVJXPLTDAOIKFZGH
SWAYXPLVUBOIKZGJRFHENMCQTD

• 3，观察变换后的字符串，倒数第六列即为flag

代码如下：

#coding:utf-8
#秘钥
key="2,5,1,3,6,4,9,7,8,14,10,13,11,12"
#密文
cipher_text = "HCBTSXWCRQGLES"

f = open("zhuanlun.txt")
str_first_encry = []

for line in f:
    line = line.strip()
    str_first_encry.append(line)

key_index = key.split(",")
str_second_encry=[]
for k in key_index:
    str_second_encry.append(str_first_encry[int(k)-1])
    print(str_first_encry[int(k)-1])

for i,ch in enumerate(cipher_text):
    line = str_second_encry[i]
    split_index = line.index(ch)
    temp=[]
    temp[0:len(line)-split_index+1] = line[split_index:len(line)]
    temp[len(temp):] = line[0:split_index]
    str_second_encry[i] = "".join(temp)
print("-------------------------------------")
for plain in str_second_encry:
    print(plain)

三，知识点

• 转轮密码