At present

graphical similarity is limited to polygonal similarity

but the problem of general graphical similarity has not been studied.We first present protocols for privately determining whether two numbers

matrices or vectors are equal based on one-way hash function.Finally

we design protocols to privately determine whether two special graphics are isomorphic

and whether two graphics are similar.We prove the security of the protocols

implement them on a personal computer and analyze their efficiency.The simulation shows that the protocol of two similar graphics is 889 times as fast as the protocol of two similar polygons.Privately determining whether two graphs are similar is completely a new secure multiparty computation problem.It has application prospects in the field of the molecular biology

mechanical engineering and terrestrial matching

etc.