I'm a bit confused with AES-256, CBC, and how it works with padding (PKCS#7).
Whenever I encrypt data of multiples of 16 bytes (the block size), extra 16 bytes are always padded at the end.
For instance, a 1600 byte file turns into a 1616 byte encrypted file.
If I look into the file with a hex editor, the last 16 bytes are not all zeros at all. I don't see any particular pattern either.
An explanation would be appreciated!