Implementación de un piloto de cifrado homomórfico en redes de sensores

Abstract

A Boeing 787 aircraft generates 240TB on a 6-hour flight. 48 hours of video are uploaded to YouTube every minute. Around 305.000 observations are made on SmartSantander every single day... In a world where information is generated at such pace, it is essential to deliver solutions that ease this traffic burden, by processing the data and providing meaningful information to the end user. The Internet of Things being a giant network of connected ’things’ (cellphones, lamps, engines... to even humans themselves) generates huge amounts of data on a daily basis. The analyist firm Gartner says that by 2020 there will be over 28.5 billion connected devices. But having these much information and not being able to derive any conclussions about it, leaves us with a great amount of meaningless data. Wireless Sensor Networks are a keyplayer in this so-called Internet of Things. Amongst its applications we find area monitoring, health care monitoring, environmental sensing, forest fire detection... to mention a few. Nodes in a WSN are characterized by very limited computing capabilites. Power consumption constraints become a major concern, therefore implying that communications should be kept at a minimum. On the other hand, we are faced with security and privacy issues, which are a must in nowadays world. With so many connected devices, how can we asure confidentiality on our sensitive information? Wireless Sensor Networks, due to the limited power resources, discard the use of conventional security solutions, such as AES. We must figure out a way to keep eavesdroppers unaware of the sensed data being monitorized in these kind of networks. The definition of secure and privacy aware solutions, that ensure at the same time limited power consumption on transmitted data, poses a great challenge. The level of engineering required to propose a solution that meets these restrictive constraints is remarkable. We propose a special kind of encryption, with homomorphic capabilities, that relies only on modular additions. These simple, non-expensive operations in computing terms make them perfectly suitable for WSNs. We propose a hybrid mesh/sensor network scheme that delivers a transparent multi-hop wireless backhaul able to handle in a secure way different kinds of data (temperature, humidity...) coming from different kinds of wireless sensor networks. In such a scheme, end-to-end privacy is ensured, as only sensor nodes and the server encrypt and decrypt the values. Forwarding intermediate nodes, such as gateways, are kept unaware of the clear data being transmitted, and are allowed to perform additions directly on the encrypted texts. We have taken this scheme one step further, and implemented it on one of SmartSantander testbed’s labs.