量子计算技术的快速发展对现有公钥密码体制构成了前所未有的潜在威胁，抗量子密码体制的设计与应用应运而生，基于同源的密码体制便是其重要组成部分。在同源密码体制中，为满足安全性和效率的双重标准，基于可交换超奇异同源的密钥交换（CSIDH）协议是目前为数不多可用的密钥交换协议。因此，本文针对CSIDH系列协议进行研究与加速，利用特征为(mod 8)的素域上的、自同态环同构于的Montgomery超奇异椭圆曲线，构造了新的同源密钥交换协议CSIDH-G。与此同时，证明了该协议中不存在其他同源密钥交换协议中存在的密钥碰撞形式，并提出了紧凑的用户私钥选取区间。最后，开展了协议运行效率实验，通过优化密钥选取区间，本文所提协议比原始CSIDH协议运行效率提高5.95%，验证了协议的准确性和有效性。该算法具有提升同源密钥交换协议效率、保证公钥验证过程简洁、避开现有CSIDH系列协议中私钥碰撞、增加Diffie-Hellman形式抗量子密码体制多样性等多方面优势。

The rapid development of quantum computing technology poses an unprecedented potential threat to the existing public key cryptosystems. Thus the design and application of post-quantum cryptosystems have emerged, and isogeny-based cryptographic protocols are crucial components of them. However, to balance both security and efficiency, the Commutative Supersingular Isogeny Diffie-Hellman (CSIDH) protocol is one of the few available key exchange protocols in the field of isogeny-based cryptography. Therefore, this paper focuses on the study and acceleration of a series of key exchange protocols based on CSIDH. Specifically, we consider Montgomery curves defined over prime fields with(mod 8), whose endomorphism rings are isomorphic to , and then construct new key exchange protocol, CSIDH-G. Meanwhile, we prove that there is no key collisions in CSIDH-G that exist in other isogeny-based key exchange protocols, and propose compact user private key selection intervals. Finally, protocol operation efficiency experiments are carried out. By optimizing the key selection interval, the efficiency of the proposed protocol is improved by 5.95% over that of the original CSIDH protocol, verifying its accuracy and effectiveness. In conclusion, the algorithm has various advantages such as enhancing the efficiency of isogeny-based key exchange protocol, ensuring convenient public key verification, avoiding the private key collisions in the existing protocol, and increasing the diversity of post-quantum cryptosystems of Diffie-Hellman form.