Decryption on Cocos2D built game [scr888]

[PikabobAlex]

Hi, the code, png and plist files except audio is encrypted. I found that it need the key to decrypt it. Can I get the key from the apk itself? If I got the key can help explain to me how do I decrypt their assets with their key? Thanks

The following link is to download the apk and some asset files:

https://www.dropbox.com/s/8zthv342nxm9f3m/apk.zip?dl=0

thanks and have a nice day