New scheme not only solved the problem of key escrow by the idea of CL-PKE but also provided fast key revocation with mediator.New scheme can resist the attack of replacing user s public key.

• 新方案利用椭圆曲线上的双线性映射构造，通过无证书加密思想解决密钥托管的问题，通过引入仲裁机构解决密钥撤销的问题，新方案能够抵抗替换用户公钥的攻击。