Suppose Alice wants to send Bob a message.
She converts her message into a set of plaintext numbers P, each less than p.
For each P, she computes
![[Graphics:Images/index_gr_1.gif]](Images/index_gr_1.gif)
She sends the numbers to Bob.
Example: send the message "cats and dogs"
![[Graphics:Images/index_gr_3.gif]](Images/index_gr_3.gif)
![[Graphics:Images/index_gr_4.gif]](Images/index_gr_4.gif)
![[Graphics:Images/index_gr_5.gif]](Images/index_gr_5.gif)
![[Graphics:Images/index_gr_6.gif]](Images/index_gr_6.gif)
Bob takes each of the numbers and computes
![[Graphics:Images/index_gr_14.gif]](Images/index_gr_14.gif)
He sends the numbers back to Alice.
![[Graphics:Images/index_gr_16.gif]](Images/index_gr_16.gif)