Lets for argument sake you are doing this but do you think you will ever receive traffic for sharing content which is already published somewhere else?
This is one reason why I emphasize a lot on unique content, out-dated topics and re-sharing of published news never brings long sustaining traffic.
It is surely legal if you are rewriting the entire post in your own words but linking the authority with attribution link to give it due credits but that credit link that you add will tell robots
"Hey all credit goes to this guy, so forget me and go and throw all
traffic there instead without wasting time on me! "
Will you simply waste all your hard work in this way?
Mashable too copied news from techCrunch when pete cashmore was in his initial stage of blogging but soon he realized that he needs to come up with his own stories in order to rank well and that played out for him!