unfortunately the (not provided) is traffic that comes from people who are signed into their google accounts and search.......Google decided to decrypt the messages....it is allso from IP addressses which come from proxy servers and so on.......not a lot we can do on this front i am afraid....

Google will not be able to crawl the secure pages that has SSL certificate and sources that are logged in, for these pages it displays the results as "not provided" while you go through the Google Analytics account.

More and more "not provided" results, soon it will be totally useless as everyone has a Google account these days. Use webmaster tools instead to see which keywords work and which not.

You can’t really influence the amount of “not provided” keywords in Google Anlytics.

When a search is made on a secure Google webpage and the result clicked, the search term isn’t passed to the destination website. Instead, these visits are grouped together in Google Analytics under the keyword "(not provided)"

I found several articles on the web about this issue. Think this one was most useful:

SEMrush Blog | How to extract the data from

So there are certain things you can use to find more data on your not provided keywords:
1. Applying filters in Google Analytics
2. Use the data from Webmaster Tools
3. Check AdWords keyword report
4. Make the use of geographical segmentation

If the user is logged into any Google product while searching, the search will be conducted over SSL and the referral data related to that search will be hidden.Google groups these users data under "Not Provided". Google does not provide any way to access user data related to “Not Provided” keywords but there are few workarounds to get insights. e.g. you can use filters to get insights of "Not Provided" users behavior in landing page report or use traffic source report to understand popular keywords for your website.