Python 常用数据类型转换

在CTF中，经常需要各种数据类型之间的转换

struct模块

官方文档: https://docs.python.org/zh-cn/3.10/library/struct.html

C语言数据结构与python bytes之间的转换

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image-20211203171927404

image-20211203171903200

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In [1]: import struct                                                                       
                                                                                            
In [2]: struct.pack("<LLLL", 1,2,3,4)                                                       
Out[2]: b'\x01\x00\x00\x00\x02\x00\x00\x00\x03\x00\x00\x00\x04\x00\x00\x00'                 
                                                                                            
In [3]: struct.pack("<LLLL",'a',2,3,4)                                                      
---------------------------------------------------------------------------                 
error                                     Traceback (most recent call last)                 
<ipython-input-3-e0808e208379> in <module>                                                  
----> 1 struct.pack("<LLLL",'a',2,3,4)                                                      
                                                                                            
error: required argument is not an integer                                                  
                                                                                            
In [4]: c = struct.pack('<I', ord('a'))                                                     
                                                                                            
In [5]: b = struct.unpack('<I', c)                                                          
                                                                                            
In [6]: b[0]                                                                                
Out[6]: 97

binascii模块

二进制和ASCII之间的转换

官方文档: https://docs.python.org/zh-cn/3.7/library/binascii.html

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In [1]: import binascii

In [2]: binascii.hexlify(b'12345')
Out[2]: b'3132333435'

In [3]: binascii.hexlify(b'12345', '-')
Out[3]: b'31-32-33-34-35'

In [4]: binascii.unhexlify(b'3132333435')
Out[4]: b'12345'

In [5]: binascii.crc32(b'123')
Out[5]: 2286445522

In [6]: hex(binascii.crc32(b'123'))
Out[6]: '0x884863d2'

进制之间的转换

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In [7]: int(0x12)
Out[7]: 18

In [8]: int('23')
Out[8]: 23

In [9]: int('1111', 2)
Out[9]: 15

In [10]: int('11', 16)
Out[10]: 17

In [11]: bin(123)
Out[11]: '0b1111011'

In [12]: int('1111011', 2)
Out[12]: 123

bytes和数字之间的转换

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In [17]: from Crypto.Util.number import long_to_bytes, bytes_to_long

In [18]: bytes_to_long(b'flag')
Out[18]: 1718378855

In [19]: hex(1718378855)
Out[19]: '0x666c6167'

In [20]: from binascii import *

In [21]: unhexlify(1718378855)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-21-43c0727e7de8> in <module>
----> 1 unhexlify(1718378855)

TypeError: argument should be bytes, buffer or ASCII string, not 'int'

In [22]: unhexlify('666c6167')
Out[22]: b'flag'

In [23]: long_to_bytes(1718378855)
Out[23]: b'flag'

列表和bytes,str类型转换

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In [28]: a = b'flag'

In [29]: b = list(a)

In [30]: b
Out[30]: [102, 108, 97, 103]

In [31]: bytes(b)
Out[31]: b'flag'
    
In [36]: a = list("flag")
In [37]: a
Out[37]: ['f', 'l', 'a', 'g']

In [38]: "".join(a)
Out[38]: 'flag'