As far as we know, there is currently no way how to convert or decrypt .crypt9 files to something else. This is usually done by users that try to access message history of latest versions of WhatsApp in attempt to read it.
Convert WhatsApp Messenger message database to WhatsApp Messenger encrypted message database backup.
We found one software available in the database for this conversion.
Google Android software - convert crypt8 to crypt9 on Android
Android app used to decrypt and convert CRYPT files
Convert from crypt8 file format
|Yes, WhatsApp Tri-Crypt (Omni-Crypt) supports crypt8 file conversion as a source file type.||Yes||No||No||No||No||No||No|
|Yes, WhatsApp Tri-Crypt (Omni-Crypt) supports crypt9 file conversion as a target file type.||Yes||No||No||No||No||No||No|
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.