bboo files are encrypted with an ‘online key’,
Bboo is the latest version of the STOP ransomware. Currently, there is only one way to decrypt .bboo files – is to use the Emsisoft STOP Djvu Ransomware Decryptor. This decryptor will be able to decrypt the encrypted files, but only those files that were encrypted with an ‘offline key’. Since your files are encrypted with an ‘online key’, this decryptor will not be able to decrypt them. The reason for this is that only the Bboo authors have online keys and there is no way to determine these keys.
Therefore, I recommend using alternative methods of recovering the contents of encrypted files. There is a chance that these methods will help you restore .Bboo files to their original state. These methods are described in the article link to which I give below:
How To Recover Encrypted Files (Ransomware file recovery)