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.
Considering .crypt9 files were only used for very short time and moved to higher version soon after, this cryp9 to html conversion is most likely very rare and more or less obsolete.
Updated: July 3, 2019
This conversion entry was verified by us and conversion was flagged as wrong or not possible.
Usually this happens when the conversion would try to convert different types of data between each other, such as audio to image, or it is not possible because incompatibility between programs, caused by closed file formats, very limited support etc.
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