Decryption of REMF (header) files

Hello,

My telephone got stolen, I made a backup every week so I have a dump of my WhatsApp (all logs), but it's encrypted. I know I had it enabled at my phone, but is it possible to decrypt or restore the chat logs ? I know the encryption is AES 256 bit, and have to be decrypted with a password or by device (but my device is stolen). How could I decrypt the messageStore.db file ? It starts with the REMF header.

Thanks.