Advances in communication technologies along with the availability of Internet and Internet of Things (IoT) devices enable users to acquire various services over the Internet. However, IoT devices are prone to attacks on the open communication channel. Many authenticated key agreement schemes have been introduced in the last decades to improve security, where most of the schemes are based on the classical number theoretic assumptions. Unfortunately, Shor’s algorithm provides the mechanism to solve the existing number theory-based problems such as discrete logarithm, integer factorization, etc. As a result, the hard problems based on number theory could be solved very efficiently on a quantum computer using Shor’s algorithm. Therefore, the design of a protocol is required that can resist all known attacks by quantum computers. To address the security issues raised by Shor’s algorithm, we propose a lattice-based key agreement protocol under ring learning with errors (RLWE). Security analysis of the proposed protocol is also presented, where both informal security andformal security analyses are followed. The analysis of security clearly indicates that the proposed scheme is provably secure under a random oracle model. In addition we study the performance of the proposed scheme, which shows the enhancement in terms of performance.