Encrypting data to pervasive contexts

Pervasive applications evolve around the user's context, making it a full-fledged communication party. However, no equivalent approach to End-to-End communication exists that allows a sender to bind data, through encryption, to a target context. Existing solutions require central infrastructures or only apply to the immediate context, restricting pervasive applications. We propose Encryption to Trusted Contexts (ETC), a communication security building block that enforces context bindings while preserving the data handling and forwarding mechanisms of the original application. Our approach leverages a Broadcast Encryption scheme to protect data in transit and binds decryption to the verification of an expressive, flexible context specification based on trusted, unforgeable sensing. Data can then be encrypted from and to any context, securely exchanged among devices, and made accessible only within the specified context. We demonstrate the feasibility of ETC in a prototypical implementation for ARM TrustZone devices, realizing communication security for context-driven, pervasive applications.