$ echo 'this is text' > text.1
$ openssl enc -aes-256-cbc -a -k "thisisapassword" -in text.1 -out text.enc
$ openssl enc -d -aes-256-cbc -a -k "thisisapassword" -in text.enc -out text.2
$ cat text.2
this is text

I can do this with openssl. Now, how do I do the same in m2crypto. Documentation is lacking this. I looked at the snv test cases, still nothing there. I found one sample, http://passingcuriosity.com/2009/aes-encryption-in-python-with-m2crypto/ (changed to aes_256_cbc), and it will encrypted/descrypt it's own strings, but it cannot decrypt anything made with openssl, and anything it encrypts isn't decryptable from openssl.

I need to be able enc/dec with aes-256-cbc as have many files already encrypted with this and we have many other systems in place that also handle the aes-256-cbc output just fine.

We use password phrases only, with no IV. So setting the IV to \0 * 16 makes sense, but I'm not sure if this is also part of the problem.

Anyone have any working samples of doing AES 256 that is compatible with m2crypto?

I will also be trying some additional libraries and seeing if they work any better.