Authentication of domains has been a crucial part of the growth of web browsing, especially for e-commerce and secure browsing. However, the digital space has expanded from web domains to include devices such as smart cars, smart houses, and other IoT devices. The future for these devices is to communicate autonomously with one another, also known as Machine-to-Machine(M2M) communication. For M2M communication, IoT devices need to be able to authenticate each other. However, IoT devices cannot take over traditional authentication mechanisms. This problem is due to the expected growth in the number of IoT devices and the varying resource capabilities of these devices. In this work, we introduce Bubblechain, a generic, decentralised, and scalable IoT authentication system. In contrast to existing works, Bubblechain can update and remove identities of IoT devices that allows them to authenticate each other in a dynamic setting. Bubblechain also creates a higher trust level for devices that belong to the same Bubble. A Bubble refers to a group of devices that belong together, such as a home or office setting. The system also provides the possibility to authenticate devices from different Bubbles. The authentication process in Bubblechain is autonomous and decentralised.