Python: binascii.a2b_hex gives “Odd-length string”

Question

I have a hex value that I\'m grabbing from a text file, then I\'m passing it to a2b_hex to convert it to the proper binary representation. Here is what I have:

Answer 1

read() doesn't strip newlines. If there's a '\n' at the end of your file, it'll be in k1.

Try binascii.a2b_hex(k1.strip()) or possibly binascii.a2b_hex(k1[:8]).

Answer 2

Are you sure the file doesn't have something extra in it? Whitespace, for instance?

Try k1.strip()

Answer 3

I'm more interested what happens if you execute the following code:

with open("./" + basefile + ".key") as key_file:
   key = key_file.read()
   print len(key), key

Care to tell? There is probably some extra character you just don't see when printing. In these cases, make sure to print the length of the string.

Answer 4

I suspect there is a trailing newline at the end of the file. Strip the string before passing it to binascii.

Note there's now also a simpler spelling: k1.strip().decode('hex').