For extra security if you are sharing the your reports, you can create external links for users, and password protect them.
To password protect a report
Navigate to Report Builder.
When creating a report on the final settings page, there is an option “Allow External Access To Report” select Yes, and then you will be prompted with "Protect With Password" if you wish to password protect the document. Select “Yes”
Type in a password of your choice and select “Build Now”.
The report build change to a status of building and once it’s complete it will come up with four lists of reports. Generally most people will use HTML, which displays your report on a web page, or CSV which downloads it into a csv format, which if you have Excel will open your report into a spreadsheet.
Provide the links to the external person in question.
Provide the password to them separately. Once they click on the link they will be prompted to input the password to view the report.
The password will remain the same for the report until it is changed. The report will be updated as often as you have told it to be built (e.g. build once a day, once a week. It will stay the same until the next nominated build date).