关于python：用不同的索引表将base64像字符串一样解码

decode base64 like string with different index table(s)

我的问题是，我已经编码了一些东西(与base64类似)，并带有一个differnet索引表：

1	0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/

而不是

1	ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/

所以当我使用base64.b64decode()时，它给我一个错误的结果。
有没有一种方法可以在转换过程中设置此表(可能作为参数)？

还是应该"转换"错误的base64字符串，我的意思是将0替换为A，将1替换为B，等等...而不是使用base64decode？如果是这样，什么是最佳且快速的解决方法？

update1：??我使用它，它可以工作，但是看起来有点慢，而且不专业。：)

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def correctbase64(str):
dicta = [ ['0','A'], ['1','B'], ['2','C'], ['3','D'], ['4','E'], ['5','F'], ['6','G'], ['7','H'], ['8','I'], ['9','J'], ['A','K'], ['B','L'], ['C','M'], ['D','N'], ['E','O'], ['F','P'], ['G','Q'], ['H','R'], ['I','S'], ['J','T'], ['K','U'], ['L','V'], ['M','W'], ['N','X'], ['O','Y'], ['P','Z'], ['Q','a'], ['R','b'], ['S','c'], ['T','d'], ['U','e'], ['V','f'], ['W','g'], ['X','h'], ['Y','i'], ['Z','j'], ['a','k'], ['b','l'], ['c','m'], ['d','n'], ['e','o'], ['f','p'], ['g','q'], ['h','r'], ['i','s'], ['j','t'], ['k','u'], ['l','v'], ['m','w'], ['n','x'], ['o','y'], ['p','z'], ['q','0'], ['r','1'], ['s','2'], ['t','3'], ['u','4'], ['v','5'], ['w','6'], ['x','7'], ['y','8'], ['z','9'] ]
l = list(str)
for i in range(len(l)):
for c in dicta:
if l[i] == c[0]:
l[i] = c[1]
break
return"".join(l)

类似的事情应该起作用(警告：未经测试的代码；可能充满错误)：

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import string

my_base64chars ="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/"
std_base64chars ="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

s = s.translate(string.maketrans(my_base64chars, std_base64chars))
data = base64.b64decode(s)

不可能使标准的base64函数(或它们调用的binascii中的较低级函数)使用自定义表。

您可以使用translate()和maketrans()：

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from string import maketrans

base64fixTable = maketrans("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/","ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/");
def correctbase64(str):
return str.translate(base64fixTable)

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print"Hello Reverse Engineering!\
"

import string
import base64

my_base64chars ="WXYZlabcd3fghijko12e456789ABCDEFGHIJKL+/MNOPQRSTUVmn0pqrstuvwxyz"
std_base64chars ="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

s = 'whatever encoded message you have that used my_base64chars index'

c = s.translate(string.maketrans(my_base64chars, std_base64chars))
data = base64.b64decode(c)
print (data)