The wireless crunch resulted in excess demand for the use of spectrum, and spectrum sharing is increasingly being proposed as a solution. To date, little research has considered how block-chain technologies can enable greater spectrum sharing. To address this gap, we develop a stylized model to show how blockchains can be leveraged to facilitate the exchange of access rights on a well-known band. To demonstrate proof of concept, we analyze available system design options, implement a small-scale test scenario, estimate the implementation and usage costs, and demonstrate how these technologies impact spectrum sharing prospects. Our exercise shows that blockchains can alleviate some of the perceived obstacles to greater sharing of spectrum.