新型三方口令认证密钥协商协议的安全性分析与改进

口令认证密钥协商(PAKA)是认证密钥协商(AKA)中的重要分支之一。研究了一种新型三方口令认证密钥协商--3REKA的安全性，发现如果参与双方的验证值丢失，将导致严重的中间人攻击，这一攻击的结果是敌手可以与参与者各自建立独立的会话密钥。描述了这一攻击，并对原协议进行了改进，提出了I-3REKA协议。安全性和性能分析表明，所提出的协议以较低的计算量实现了参与双方的安全通信。

Analysis and improvement on new three-party password-based authenticated key agreement protocol

Password-based Authenticated Key Agreement (PAKA) is an important research point of Authenticated Key Agreement (AKA) protocols. The authors analyzed a new protocol named three-party Round Efficient Key Agreement (3REKA) and found that if the verification values were stolen or lost, the adversary could initiate the man-in-the-middle attack. The result of this attack was serious: the adversary could establish two session keys with two different participants. This attack was described and an improved protocol called Improved 3REKA (I-3REKA) was proposed in this paper. The analysis on the security and performance show that the proposed protocol can realize secure communication with lower computational cost.