Dear Monks,
"...using the provided password as both the key and initialisation vector..."
That looks like your problem. and we can't verify the results without knowing the exact inputs to the conversion. I suspect, as others have stated, that you are taking the 8 byte password and converting to hex to get the 16 bytes that AES requires. That will definitely give you a wrong answer. The way encryption works is: change any character and you get an entirely different encrypted result.
Ask you client for the
exact '-key' and '-iv' and then see if it works. If he gave you the password, then the '-key' and '-iv' values should be 'no problem'.
Regards...Ed
"Well done is better than well said." - Benjamin Franklin