You don't decrypt manually; you let WhatsApp do the work, then re-extract the decrypted database using a memory dump technique.
Processing chunk 1... OK Processing chunk 2... OK Decrypting tables...
To decrypt a WhatsApp database, you must obtain the unique encryption key file, which is typically hidden in protected system folders. Once you have this key, you can use forensic or community tools to transform the encrypted file back into a readable SQLite database. Understanding the .crypt14 File
