[英]decode base64 like string with different index table(s)
我的問題是,我有一些帶有不同索引表的編碼(base64 like):
0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/
代替
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/
所以當我使用base64.b64decode()
它會給我一個錯誤的結果。 有沒有辦法在轉換時設置此表(可能作為參數)?
或者我應該“轉換”錯誤的base64字符串,我的意思是將0替換為A,將1替換為B等等...而不是使用base64decode? 如果是這樣,最好的和快速的解決方法是什么?
update1 :我使用它,這有效,但看起來有點慢,而且不專業。 :)
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)
這樣的東西應該工作(警告:未經測試的代碼;可能充滿錯誤):
import string
my_base64chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/"
std_base64chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
s = s.translate(string.maketrans(my_base64chars, std_base64chars))
data = base64.b64decode(s)
不可能使標准的base64
函數(或者它們調用的binascii
中的低級函數)使用自定義表。
你可以使用translate()
和maketrans()
:
from string import maketrans
base64fixTable = maketrans("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/", "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/");
def correctbase64(str):
return str.translate(base64fixTable)
這將處理錯誤TypeError: Incorrect padding
from string import maketrans
import base64
STANDARD_ALPHABET = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
CUSTOM_ALPHABET = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/'
def correctbase64(input):
DECODE_TRANS = maketrans(CUSTOM_ALPHABET, STANDARD_ALPHABET)
newStr = input.translate(DECODE_TRANS)
# Add '=' char at the end of the string
newStr += '='
return base64.b64decode(newStr)
print custom_base64decode('x/Tcw/g') # hello
print "Hello Reverse Engineering!\n"
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)
使用maketrans構建轉換表,然后從第一個字母轉換為第二個字母。 然后base64解碼。
import string
import base64
def decode(str):
#make a translation table.
table = string.maketrans(
#your alphabet
string.digits + string.uppercase + string.lowercase + "+/",
#the original alphabet
string.uppercase + string.lowercase + string.digits + "+/"
)
#translate
str.translate(s, table)
#finally decode
return base64.b64decode(str)
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.