An IBE scheme with threshold to decryption for groups

In fact, every group has one´s identity which is different from any other groups the same as a person has own identity which is different from any other persons. In an IBE scheme, we can think the sender or the receiver is a corresponding group. In practical, it is necessary that using the identity of a group to encrypt a message and sending it to other group or a person in some time. If the message is encrypted for a group, we hope that in some time there are several members of the receiving group are needed to decrypt the message. In this paper we first present the idea that combining the threshold in an IBE scheme for groups decryption, and proposes a scheme for above idea that Threshold-Based for decryption in an IBE scheme.