Hi ! The logical to remember with Public , Private Keys is about 2 crypting channels. From both sides, 2 differents Keys will operate. Like all cryptos, one can be reverse , not the other. But the A to B, B to A must transmit all datas, and verify them. Look at what can be switch : ( What is surrounding ? ) Computer A , Computer B Keys A , Key B Private function crypto Public function crypto Clock from A(all in) , Clock from B(all in) checksum A , checksum B while you ensure no errors of receiver . The work is all done. It's "pair" working.