[Cryptography-dev] Type error using CBC IV

[Fennell, Felix W.]

Hi,

I'm not sure if this the best place to ask for support using Cryptography, apologies if it isn't.

I am trying to recover and decrypt some data encrypted using Blowfish. I have sample code in PHP which works but I am unable to translate it into Python, which is needed for the end goal of this project.

My issue seems to stem from the IV value used not being the right type and I seem unable to convert the IV I've been given into the correct type.

My code so far is here [1]

The output I get is here [2], the main error being:

"TypeError: initializer for ctype 'unsigned char *' must be a bytes or list or tuple, not str"

My debug line [3] says that the IV is 'bytes' and not a 'str' so I'm not sure what is causing this error.

I briefly experimented with the ctypes library to convert the IV but this got me no further.

In searching this error I found numerous cases where the cause was passing a string instead of bytes, solved by calling 'encode('utf8') or similar - but I believe I've already accounted for this by using b'value' rather than just 'value'. I did also try using a normal string and calling encode but it made no difference.

I also experimented using 'os.urandom(32)' to generate a value just to check something would work. It did but I got an error about the wrong length (which makes sense), however the 'type(iv)' debug line said this was 'bytes' as well so I'm not sure how my 'bytes' is different.

If useful, I am using Python 3.6 (through the official Docker image) and Cryptography 2.2.2.

Have I missed something completely obvious with this?

I'm aware the choice of IV is not secure, and that Blowfish is deprecated. Part of this project is to move to a newer encryption method but I need to be able to read the existing data first.

Any help would be very gratefully received.

Thanks,
Felix.

[1] https://gist.github.com/felnne/b399a0918960696aca5c4324392a72f7

[2] https://gist.github.com/felnne/b399a0918960696aca5c4324392a72f7#gistcomment-2619903

[3] https://gist.github.com/felnne/b399a0918960696aca5c4324392a72f7#file-main-py-L8


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