How to create python bytes object from long hex string?

Question

I have a long sequence of hex digits in a string, such as

000000000000484240FA063DE5D0B744ADBED63A81FAEA390000C8428640A43D5005BD44

only much longer, several kilobytes. Is there a builtin way to convert this to a bytes object in python 2.6/3?

Note that the answers below may look alike but they return different types of values. s.decode('hex') returns a str, as does unhexlify(s). bytearray.fromhex(s) returns a bytearray. Given the wording of this question, I think the big green checkmark should be on bytearray.fromhex(s), not on s.decode('hex'). — Paul Hoffman
– Paul Hoffman, Commented Dec 18, 2013 at 2:04
Possible duplicate of hexadecimal string to byte array in python — Ciro Santilli OurBigBook.com
– Ciro Santilli OurBigBook.com, Commented May 17, 2017 at 8:13
How can it be a duplicate of a question created 2 years later? — recursive
– recursive, Commented May 17, 2017 at 14:48
@CiroSantilli郝海东冠状病六四事件法轮功 A byte string isn't a byte array. stackoverflow.com/questions/1740696/… — LarsH
– LarsH, Commented Nov 5, 2020 at 11:30
@LarsH fair enough. @ recursive: date is not the main factor: meta.stackexchange.com/questions/147643/… — Ciro Santilli OurBigBook.com
– Ciro Santilli OurBigBook.com, Commented Nov 5, 2020 at 11:42

vili · Accepted Answer · 2009-01-14 17:56:39Z

158

result = bytes.fromhex(some_hex_string)

edited Jan 14, 2009 at 17:56

answered Jan 14, 2009 at 17:50

vili

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1 Comment

Klaws Over a year ago

The fromhex() method (of both bytes and bytearray) will also work when the hex numbers are separated by spaces. Very convenient!

Jens · Accepted Answer · 2016-04-09 00:18:04Z

122

Works in Python 2.7 and higher including python3:

result = bytearray.fromhex('deadbeef')

Note: There seems to be a bug with the bytearray.fromhex() function in Python 2.6. The python.org documentation states that the function accepts a string as an argument, but when applied, the following error is thrown:

>>> bytearray.fromhex('B9 01EF')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: fromhex() argument 1 must be unicode, not str`

edited Apr 9, 2016 at 0:18

Jens

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answered Jun 18, 2013 at 3:37

Jim Garrison

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6 Comments

berto Over a year ago

And one additional step, I wanted a byte string (e.g. Python 3's b'\x04\xea[...]'), which you can get from a bytearray with bytes(bytearray.fromhex('deadbeef'))

Martijn Pieters Over a year ago

@berto: in that case there is a more direct route in the form of binascii.unhexlify().

Mike Martin Over a year ago

This answer does not do what the question asked. It returns a mutable array of bytes, not a python bytestring. That's like returning an array of strings rather than a string.

LarsH Over a year ago

@MartijnPieters Seems like bytes.fromhex() is also more direct, and a bit less obscure / more parsimonious. docs.python.org/3/library/stdtypes.html#bytes.fromhex

Martijn Pieters Over a year ago

@LarsH: that method is not available in older Python 2 releases. That doesn't matter any more today, but it was an issue in 2016.

|

Brian · Accepted Answer · 2009-01-14 17:47:20Z

46

You can do this with the hex codec. ie:

>>> s='000000000000484240FA063DE5D0B744ADBED63A81FAEA390000C8428640A43D5005BD44'
>>> s.decode('hex')
'\x00\x00\x00\x00\x00\x00HB@\xfa\x06=\xe5\xd0\xb7D\xad\xbe\xd6:\x81\xfa\xea9\x00\x00\xc8B\x86@\xa4=P\x05\xbdD'

answered Jan 14, 2009 at 17:47

Brian

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1 Comment

Abbafei Over a year ago

codecs.decode('0a0a0a', 'hex_codec') should work for 2.x and 3.x :-)

Scott Griffiths · Accepted Answer · 2011-05-29 16:47:29Z

39

Try the binascii module

from binascii import unhexlify
b = unhexlify(myhexstr)

edited May 29, 2011 at 16:47

Scott Griffiths

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answered Jan 14, 2009 at 17:46

Crescent Fresh

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5 Comments

technomalogical Over a year ago

Two ways to do it in 2.x, three ways in 3.x. So much for "there's only one way to do it"...

Crescent Fresh Over a year ago

Other two ways are more 'built-in' so I would actually use one of those.

tzot Over a year ago

@technomalogical: your comment is irrelevant to the answer; perhaps you should delete it and change it into a post to comp.lang.python .

nosklo Over a year ago

@technomalogical: I agree with ΤΖΩΤΖΙΟΥ. Also, you got it wrong. The correct phrase is: There should be one-- and preferably only one --obvious way to do it.

Scott Griffiths Over a year ago

Note that in Python 3.2 (whether by design or a bug I'm not sure) unhexlify now won't accept a string, but only bytes. Pretty silly really, but it means you'd need to use b = unhexlify(bytes(myhexstr, 'utf-8'))

snakecharmerb · Accepted Answer · 2019-08-02 10:40:05Z

2

import binascii

binascii.a2b_hex(hex_string)

Thats the way I did it.

edited Aug 2, 2019 at 10:40

snakecharmerb

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answered Jul 30, 2019 at 6:39

JustPlayin

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