Efficient quantum multi-authority attribute-based encryption and generalizations

The Internet of Things, smart grids, etc. contain processors, sensors, and communication hardware that exchange information with other devices in the network and act on the acquired information. These generate huge amounts of data which are stored in cloud/edge servers managed by third parties and are exposed to the internet. The data often include sensitive information, and the protection of such privacy-sensitive data is important. Attribute-based encryption is one of the most popular methods to address security and privacy challenges encountered in such cases. However, most of the existing classical attribute-based schemes are not secure against quantum attacks and can be broken using Shor’s algorithm. Given this, secure (single-authority) quantum attribute-based schemes have been recently studied. To the best of our knowledge, quantum multi-authority attribute-based schemes have not received much attention and are missing in the literature. Here, we propose a novel construction of a quantum multi-authority attribute-based encryption scheme. The privacy of the encryption scheme is derived using trap codes and quantum secret-sharing schemes. Our construction is based on discrete-time quantum walks and is shown to be portable and usable in several variants of multi-authority schemes. We also demonstrate quantum advantage in terms of computational cost.