I don't know what you think about confidentiality, but let me briefly talk about my thoughts.

First of all, if the documents you send do not involve state secrets or sensitive information, you can use WeChat to handle them.

Secondly, the data encryption measures and protection measures of WeChat itself should be reliable, and it is almost impossible to break into the server from the outside to view your information.

Third, if the physical environment and network environment where you lead to view files are safe enough, it will be credible.

Fourth, if you and the leader don't actively forward it to others, there is no possibility of leaking secrets.

Fifth, I suggest you take further encryption measures, such as setting the password of the inquiry itself, setting the password of the compressed package, and sending the mail. And you can also prompt the leader burn after reading to delete it in time.

Finally, papers and drawings may be related to the interests of yourself and your unit, so it is recommended to pay attention to information security.

If you want to know more about confidentiality and information security measures, you can contact me.