单刷好幸苦。

Crypto-15

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Some classics crypto task ! Cesar maybe !!
Author : Sold1er
crypto-15.txt

进行一次rot13后得到原文：

def encode(story, shift):
  return ''.join([
            (lambda c, is_upper: c.upper() if is_upper else c)
                (
                  ("abcdefghijklmnopqrstuvwxyz"*2)[ord(char.lower()) - ord('a') + shift % 26],
                  char.isupper()
                )
            if char.isalpha() else char
            for char in story
        ])
def decode(story,key):
	pass
if __name__ == '__main__':
	key = [_YOUR_KEY_HERE_]
	print decode("Piug_Pibbm{Q35oF_3BQ0R3_4F3_B0H_G3QiF3_OH_4ZZ}",key)

对Piug_Pibbm{Q35oF_3BQ0R3_4F3_B0H_G3QiF3_OH_4ZZ}进行凯撒解码。得到flag：

1	Bugs_Bunny{C35aR_3NC0D3_4R3_N0T_S3CuR3_AT_4LL}

Crypto-20

++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>----. >+++++++++++++++++. --------------. ++++++++++++. --------------------. <. >++++++++++++++++++++++. -------. . +++++++++++. ++. <. >---------. <--------------. ---. +++++++++++++++++++++++++++++. +++++++++++++++++. -------------------------. >+++. <<++++++++++++. . >>++++++++.

brainfuck解码，得到flag：

1	Bugs_Bunny{Br41N_Fu**}

Crypto-25

题目文件下载下来后打开发现是ook编码，放到下面网站中解码：

1	http://tool.ph0en1x.com/brainfuck/

得到flag：

1	Bugs_Bunny{Ju5T_OoK!}

Scy way

Decrypt My Secret And Win!
IHUDERMRCPESOLLANOEIHR
Bugs_Bunny{flag}
Author: TnMch

栅栏密码。

1 2	IHUDERMRCPE SOLLANOEIHR

得到flag：

1	Bugs_Bunny{ISHOULDLEARNMORECIPHER}

Crypto-50

就一直base64的解密。得到flag：

1	Bugs_Bunny{N0T_H4Rd_4T_4ll}

babyRsa

1 2	N: 20473673450356553867543177537 e: 17

在factordb上把N进行分解如下，得到p和q：

1 2	p = 2165121523231 q = 9456131321351327

用以下脚本解出flag：

n = 20473673450356553867543177537
p = 2165121523231
q = 9456131321351327
e = 17
def egcd(a, b):
    if a == 0:
      return (b, 0, 1)
    else:
      g, y, x = egcd(b % a, a)
      return (g, x - (b // a) * y, y)
def modinv(a, m):
    g, x, y = egcd(a, m)
    if g != 1:
      raise Exception('modular inverse does not exist')
    else:
      return x % m
def decrypt(c, d, n):
    return pow(c, d, n)
d = modinv(e, (p-1)*(q-1))
print d
encfile = open('enc.txt','rb')
decfile = open('flag.txt','wb')
for i in range(48):
	enc = encfile.readline()[:-1]
	print enc
	decfile.write(str(chr(decrypt(long(enc),d,n))))
encfile.close()
decfile.close()

运行到最后时会说overflow出错，不过不影响flag。最后的flag如下：

1	Bugs_Bunny{Baby_RSA_Its_Cool_Lik3_school_haHAha}