Decode详解

http://www.shiyanbar.com/ctf/1831 Decode： flag格式:ctf{} 0x25346425353425343525333525343325366125343525373725346425353125366625373825346425343425363725346225346625353425366225346225346425353425343525373825343325366125343525373725346625353125366625373825346425343425343525346225346425353425343525333225343325366125343525373825346425353125366625373825346425353425353525346225346 4253534253431253330253433253661253435253737253465253531253666253738253464253661253435253462253466253534253633253 4622534642535342534352537372534332536612536622533342534332536612536622533332534332536612534352537382534652534312 53364253364 解： 1.Decode，肯定是运用各种解码 ox表示十六进制，从网上了解到十六进制编码是把整个数字4个一分求一个字符这样会超出ascii码范围， 网上的数据都是以ox开头比如网上数据ox12ox96ox48.... 而本题数据就开头是ox唯一一个,那么我们就两个一分。

十六进制解码转化字符代码如下：

#十六进制解码转化字符代码如下 str='253464253534253435253335253433253661253435253737253464253531253666253738253464253434253637253462253466253534253662253462253464253534253435253738253433253661253435253737253466253531253666253738253464253434253435253462253464253534253435253332253433253661253435253738253464253531253666253738253464253534253535253462253464253534253431253330253433253661253435253737253465253531253666253738253464253661253435253462253466253534253633253462253464253534253435253737253433253661253662253334253433253661253662253333253433253661253435253738253465253431253364253364' def HexDe(str): decstr = '' #i+=4 for i in range(0,len(str),2): decstr +=chr(int(str[i:i + 2],16))#unichr()跟chr()一样，只不过返回的是Unicode字符 return decstr print(HexDe(str))

2.这就得到结果，很显然这是url编码 MTE5CjEwMQoxMDgKOTkKMTExCjEwOQoxMD EKMTE2CjExMQoxMTUKMTA0CjEwNQoxMjEK OTcKMTEwCjk4Cjk3CjExNA== 提供一个网址解它http://tool.chinaz.com/Tools/Unicode.aspx 3.解得： MTE5CjEwMQoxMDgKOTkKMTExCjEwOQoxMD EKMTE2CjExMQoxMTUKMTA0CjEwNQoxMjEK OTcKMTEwCjk4Cjk3CjExNA==

4.利用Base64代码得到：

#-*- coding: utf-8 import base64 str=b'MTE5CjEwMQoxMDgKOTkKMTExCjEwOQoxMDEKMTE2CjExMQoxMTUKMTA0CjEwNQoxMjEKOTcKMTEwCjk4Cjk3CjExNA==' str=base64.b64decode(str) print(str) str=str.decode('ascii')#bytes解码会得到str print(str)

119 101 108 99 111 109 101 116 111 115 104 105 121 97 110 98 97 114

5.利用Ascii代码得到welcometoshiyanbar

#从数字转换到字母 按照ASCII编码 L=[119,101,108,99,111,109,101,116,111,115,104,105,121,97,110,98,97,114] for x in L: print(chr(x),end='')

得到flag:ctf:{welcometoshiyanbar}