Abstract: Aiming at multi-tenant environments for cloud computing,introducing the trusted third party is into cloud security solutions,this paper proposed a new cloud security model based on trusted third party．Then we designed the authentication protocol and a multi-tenant resource allocation algorithm based on TTP．Finally,the CloudSim simulation tools were used for simulation and performance analysis,and Short Jobs First strategy,First-come First-served policy were compared with TTP strategy in successful implementation rate of resources．The experimental results show that the model provides the highest credibility cloud node resources to cloud users,builds a trust web between entities effectively,verifies the correctness of the data and the correctness of the data exchange,and provides a multi-level,end-to-end security services in the distributed environment.

Key words: Cloud computing,Multi-tenant,Trusted third party,Cloud security