攻防世界—base64stego

文章目录

攻防世界---base64stego
题目
用的的知识
- base64
- - base64编码实现
  - base64解码实现
  - 总结
- 伪加密
- - 无加密
  - 真加密
- base64隐写
题解
- 伪加密
- txt文件一大串base64编码
- base64隐写

题目

菜狗经过几天的学习，终于发现了如来十三掌最后一步的精髓

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用的的知识

base64

base64编码实现

为每个编码占6位

利用字典建立一一对应

编码的每个字符转成 8位的对应的ascll
转后取每6位换成字典对应的字符
“=” 为不足6位补0 替换
如果字节数不是 3 的倍数, 则位数就不是 6 的倍数,
在编码后的字符串后面添加 1 个或 2 个等号”=”, 表示所添加的零值字节数.

base64解码实现

同理,把编码逆回来

总结

l = "A B C D E F G H I J K L M N O P Q R S T U V W X Y Z a b c d e f g h i j k l m n o p q r s t u v w x y z 0 1 2 3 4 5 6 7 8 9 + /".split()ll = []
for i in range(len(l)):t = bin(i)[2:]if(len(t) != 6):t = "0"*(6-len(t))+tll.append(t)d = {}
for i in range(len(l)):d[l[i]] = ll[i]def xiao_e_base64(str):b_str = ""temp = ""for i in str:b = bin(ord(i))[2:]if(len(b) != 8):b_str += "0"*(8-len(b))+belse:b_str += bf = len(b_str) % 3b_str += "000000"*fstr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"for i in range(0, len(b_str), 6):if("1" in b_str[i:i+6]):temp += str[int(b_str[i:i+6], 2)]return temp+"="*fdef xiao_d_base64(str):b_str = ""temp = ""for i in str:if(i == "="):b_str += "000000"else:b_str += d[i]for i in range(0, len(b_str), 8):temp += chr(int(b_str[i:i+8], 2))return tempprint(xiao_e_base64("Tr0y3uew"))
print(xiao_d_base64("VHIweTN1ZXc="))

伪加密

无加密

压缩源文件数据区的全局加密应为00 00
- 且压缩源文件目录区的全局方式标记应当为00 00
假加密
- 压缩源文件数据区的全局加密应为00 00
  - 且压缩源文件目录区的全局方式标记应当为09 00

真加密

压缩源文件数据区的全局加密应为09 00
- 且压缩源文件目录区的全局方式标记应当为09 00

base64隐写

https://www.tr0y.wang/2017/06/14/Base64steg/

有一个 ‘ = ’ 可以隐藏两位数据两个 ‘ = ’可以隐藏四位，‘ = ’最多只能有两位。

题解

伪加密

搜索 50 4B 把09->00 或者把最后 PK…这一段删了

txt文件一大串base64编码

利用python base64 文件读解密

import base64f = open("stego.txt", 'r')
lines = f.read().split("\n")
for i in lines:try:print(base64.b64decode(i.encode()).decode(), end="")except:print(i)

翻译下

没啥用…

base64隐写

提取可以隐写的最后2-4位，再拼接最后转回ascii码flag就出来了

总结

l = "A B C D E F G H I J K L M N O P Q R S T U V W X Y Z a b c d e f g h i j k l m n o p q r s t u v w x y z 0 1 2 3 4 5 6 7 8 9 + /".split()ll = []
for i in range(len(l)):t = bin(i)[2:]if(len(t) != 6):t = "0"*(6-len(t))+tll.append(t)d = {}
for i in range(len(l)):d[l[i]] = ll[i]hide = ""
f = open("stego.txt", 'r')
lines = f.read().split("\n")
for i in lines:if i[-1:] == '=':if(i[-2:-1]) == '=':hide += d[i[len(i)-3]][2:]else:hide += d[i[len(i)-2]][4:]for i in range(0,len(hide),8):print(chr(int(hide[i:i+8],2)),end="")

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攻防世界(杂项篇MISC)---base64stego

攻防世界—base64stego

文章目录

题目

用的的知识

base64

base64编码实现

base64解码实现

总结

伪加密

无加密

真加密

base64隐写

题解

伪加密

txt文件一大串base64编码

base64隐写

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