Password Hash - External drive encrypted with Disk Utility don't laugh, but I have encrypted my external drive and cannot remember the password.

The good thing is, the password was really bad (only four digits), so I could get it with brute force. You don't have to tell me that it is ridiculous to encrypt a drive with such a weak password. I do know this. I just don't know anymore why I encrypted the drive. Probably just because I could 

For the brute force I already downloaded John the Ripper. My problem is that I don't know where to get the password hash from the drive. With google I only could find tutorials how to get the hash for Windows or Mac user accounts. But this was not helpful.

Can anyone tell me where to get the hash?

I am working with OS X High Sierra 10.13.3 and the drive is a WD Elements external drive.

thanks in advance 

Sebastian
The disk encryption employed by Disk Utility does not store your password as a hash. Thus is there no hash to get, and John the Ripper is not the right program for brute forcing this type of encryption.

For File Vault encrypted disks, you could look at a program such as VileFault to try brute forcing the passphrase.