Convert hexadecimal to normal string

Question

I'm using Python 3.3.2 and I want convert a hex to a string.

This is my code:
junk = "\x41" * 50 # A
eip = pack("<L", 0x0015FCC4)
buffer = junk + eip

I've tried use

>>> binascii.unhexlify("4142")
b'AB'

... but I want the output "AB", no "b'AB'". What can I do?

Edit:

buffer = junk + binascii.unhexlify(eip).decode('ascii')

binascii.Error: Non-hexadecimal digit found

The problem is I can't concatenate junk + eip.

Thank you.

possible duplicate of [Decode Hex String in Python 3](http://stackoverflow.com/questions/3283984/decode-hex-string-in-python-3) — Ja͢ck, Mar 10 '14 at 02:51
mm.. no. I want concatenate no representable characters (\x90 for example). — user3270009, Mar 12 '14 at 01:39

metatoaster · Answer 1 · 2014-03-12T02:06:06.247

1

What that b stands for is to denote that is a bytes class, i.e. a string of bytes. If you want to convert that into a string you want to use the decode method.

>>> type(binascii.unhexlify(b"4142"))
<class 'bytes'>
>>> binascii.unhexlify(b"4142").decode('ascii')
'AB'

This results in a string, which is a string of unicode characters.

Edit:

If you want to work purely with binary data, don't do decode, stick with using the bytes type, so in your edited example:

>>> #- junk = "\x41" * 50 # A
>>> junk = b"\x41" * 50 # A
>>> eip = pack("<L", 0x0015FCC4)
>>> buffer = junk + eip
>>> buffer
b'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\xc4\xfc\x15\x00'

Note the b in b"\x41", which denote that as a binary string, i.e. standard string type in python2, or literally a string of bytes rather than a string of unicode characters which are two completely different things.

edited Mar 12 '14 at 02:06

answered Mar 10 '14 at 02:07

metatoaster

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It's a part of an exploit, and buffer contain hexadecimal characters no playable in ascii-mode or utf-8-mode (\x90 por example), but ty. – user3270009 Mar 12 '14 at 01:34
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Then you should just leave it as a bytestring if that's binary data. – metatoaster Mar 12 '14 at 01:38
junk = b"\x41" * 50 # A eip = pack(" – user3270009 Mar 12 '14 at 01:57
Representation of strings types have changed completely from python2 to python3. See edited answer. – metatoaster Mar 12 '14 at 02:09

score 0 · Answer 2 · edited May 23 '17 at 11:49

0

That's just a literal representation. Don't worry about the b, as it's not actually part of the string itself.

See What does the 'b' character do in front of a string literal?

edited May 23 '17 at 11:49

Community

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answered Mar 10 '14 at 02:04

Matt Ball

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Oh, better :) But I can't concatenate eip to junk :/ – user3270009 Mar 12 '14 at 01:34

Convert hexadecimal to normal string

2 Answers2