SDDR: Light-Weight, Secure Mobile Encounters
Matthew Lentz, Viktor Erdélyi, Paarijaat Aditya, Elaine Shi, Bobby Bhattacharjee, Peter Druschel · 2014
Emerging mobile social apps use short-range radios to dis-cover nearby devices and users. The device discovery proto-col used by these apps must be highly energy-efficient since it runs frequently in the background. Also, a good protocol must enable secure communication (both during and after a period of device co-location), preserve user privacy (users must not be tracked by unauthorized third parties), while providing se-lective linkability (users can recognize friends when strangers cannot) and efficient silent revocation (users can permanently or temporarily cloak themselves from certain friends, unilater-ally and without re-keying their entire friend set). We introduce SDDR (Secure Device Discovery and Recog-nition), a protocol that provides secure encounters and satisfies all of the privacy requirements while remaining highly energy-efficient. We formally prove the correctness of SDDR, present a prototype implementation over Bluetooth, and show how ex-isting frameworks, such as Haggle, can directly use SDDR. Our results show that the SDDR implementation, run continuously over a day, uses only ∼10 % of the battery capacity of a typical smartphone. This level of energy consumption is four orders of magnitude more efficient than prior cryptographic protocols with proven security, and one order of magnitude more effi-cient than prior (unproven) protocols designed specifically for energy-constrained devices. 1