If you really want to use Single DES, the key must be 8 bytes long, not 16 (the exception string is clearly wrong and misleading though).
If you want to actually use Triple DES, use must use the DES3 module, not the DES module.
In either case, the IV (3rd parameter to new() method) must be 8 bytes long, not 16.
If you really want to use Single DES, the key must be 8 bytes long, not 16 (the exception string is clearly wrong and misleading though).
If you want to actually use Triple DES, use must use the DES3 module, not the DES module.
In either case, the IV (3rd parameter to new() method) must be 8 bytes long, not 16.