Crypto headaches.

M.-A. Lemburg mal at egenix.com
Wed Feb 18 15:10:42 CET 2009


On 2009-02-18 14:23, SamG wrote:
> Hi,
> 
> Using the python's Crypto.Cipher.Blowfish is create and encrypted file
> in the CBC mode. Now... when try to decrypt it with OpenSSL i get an
> error stating "bad magic number".

Are you getting the error message from openssl ? It looks a lot
like an error message from Python.

> I tried
> $ cat encr-file | openssl bf-cbc -d -pass pass:sam > org-file
> or
> $ openssl bf-cbc -d -pass pass:sam -in encr-file -out org-file
> 
> BTW, decryption using a python code works well. But i m of the
> impression a file encry with one program should/can be decrypt with
> another program (in my case openssl) using the same parameters.

Ideally, that should work, but you also have to make sure that
the following two details are the same for both applications:

 1. the way padding is done (Blowfish is a block cipher)

 2. the way the initialization vector is set

Otherwise the two won't interoperate properly.

-- 
Marc-Andre Lemburg
eGenix.com

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