关键词: 会话发起协议, 安全机制, 基于身份的密码学, 身份认证, 密钥协商

Abstract: Along with Session Initiation Protocol（SIP） application in network communication widely，especially in mobility area，many wireless equipments are used.These devices have limited capacity of storage and computing.In this paper，the security schemes of SIP are discussed and analyzed.Furthermore，a new authentication and key agreement scheme based on identity is proposed，which assures the integrity and authenticity of SIP message during transmission and consults with share key.The scheme doesn’t need any public key certificate；user’s SIP URI is used as his public key.It needs less storage，computing capacity and communication cost，so it is simple and effective.

Key words: Session Initiation Protocol（SIP）, security mechanism, Identity Based Cryptography（IBC）, authentication, key agreement