Nowadays, Whatsapp has changed their sdcard method, which is IMPOSSIBLE to decode the database except using a key file which is located on the restricted area where ROOT is necessary. So, without rooting your device it is NOT possible to decrypt it. Moreover, the previous application whatcrypt or similar are totally useless code as you need a rooted device to work. If you have a rooted device you directly take the original database, instead of using the sdcard backup. Dont waste more time, whatsapp sdcard backup is now secure