I found the following info on the KeePass homepage[0]: >For both algorithms [AES/Twofish], a 128-bit initialization vector (IV) is generated randomly each time

I found the following info on the KeePass homepage[0]: >For both algorithms [AES/Twofish], a 128-bit initialization vector (IV) is generated randomly each time you save the database. >This allows multiple databases to be encrypted using the same key without observable patterns being revealed. I'm no crypto expert, but I think this also covers multiple versions of your kdb file. [0]: http://keepass.info/help/base/security.html#secencrypt http://keepass.info/help/base/security.html#secencrypt