PRUB: A Privacy Protection Friend Recommendation System Based on User Behavior

Box 4

Attribute exchange protocol.

Client                             Client  

() Calculate

                                () Calculate

() Calculate                           () Calculate

() Produce and send a promise                         () Produce and send a promise

among which is an ordered                              among which is an ordered

sequence of                              sequence of

() Calculate and exchange the                             () Calculate and exchange the

proportion of the same attribute.                              proportion of the same attribute.