Why does Codeigniter do this? I mean isn\'t it very insecure if users can see which data is stored in their session? And and what if they change a value in the cookie?
check this out: https://bitbucket.org/xperez/core-session-storage-for-codeigniter
its a wrapper for ci_session interface with native php sessions and thus works also with memcached and not DB.
Cheers