Many problems in cryptology and information security fields are eventually converted to time-consuming computations which usually need to be completed over heterogeneous and geographically distributed computers.The analysis

design and application of a cryptographic algorithm usually depend on its concrete computing settings;different algorithms and different implementations of an algorithm need different computing environments.In this paper

the targets and features of different cryptographic computations are firstly analyzed according to their computing requirements;the corresponding computing modes are put forward;and a general purpose cryptographic computing model on grid is given.The task dividing policy

resource allocation and load balance for the model are then discussed.The implementation and the performance evaluation for the model based on Globus Toolkit 4 are further presented.