NSSCTF刷题wp——多表替换密码

NSSCTF Crypto模块

多表替换密码

[AFCTF 2018]Vigenère ID:945

解压文件，一个c语言加密程序和密文，打开加密程序

经过分析和题目提示知，这是维吉尼亚加密。先直接爆破一手

得flagafctf{Whooooooo_U_Gotcha!}

[NCTF 2019]Sore ID:1290

打开文件

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

网站解密

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发现不对，回看加密程序

from string import ascii_letters
from flag import flag


ctoi = lambda x: ascii_letters.index(x)
itoc = lambda x: ascii_letters[x]

key = flag.strip('NCTF{}')
len_key = len(key)

plaintext = open('plaintext.txt', 'r').read()

plain = ''.join(p for p in plaintext if p in ascii_letters)
cipher = ''.join( itoc( ( ctoi(p) + ctoi( key[i % len_key] ) ) % 52 )  for i,p in enumerate(plain) )

open('ciphertext.txt', 'w').write(cipher)

发现密钥着重于加密的key
即得flagvlbeunuozbpycklsjxlfpaq

[UTCTF 2020]Hill ID:202