Happened same with me. This is happening because the App Store is looking for a working connection on en0 port and it is not getting anything anything on it due to which it says the device cannot be verified.
Your task is to switch the en0 and en1 assignments basically.
Just copy the files ‘preferences.plist‘ and ‘NetworkInterfaces.plist‘ from /Library/Preferences/SystemConfiguration to Desktop as a backup and delete it from /Library/Preferences/SystemConfiguration
Restart your Mac and try to login into the App Store
Worked for me!
原文：http://www.cnblogs.com/fastdream/p/6241316.html