Green and Sustainable Cyber-Physical Security Solutions for Body Area Networks

1. Definition: BAN - A network of health & environmental monitoring sensors deployed on a person managing their health. Principal Features: Continuous real time monitoring Remove time & space restrictions on care Improved deployability Ideal for life-saving scenarios: Enables caregivers on field to make informed decisions about treatment of soldiers in time-constrained scenarios. PKA Total Energy Consumption for Different Vault Sizes PKA Computation Energy Consumption for Different Vault Sizes 1.3 0.7 Sender(Radio ON) Sender(Radio ON) Sender(Radio OFF) Sender(Radio OFF) 1.2 Receiver(Radio ON) Receiver(Radio ON) 0.6 Receiver(Radio OFF) Receiver(Radio OFF) Sensing 1.1 0.5 1 0.9 0.4 Energy (Joules) Energy (Joules) 0.8 0.3 0.7 0.6 0.2 cfi,di 0.5 0.1 0.4 0 1000 1500 2000 2500 3000 3500 4000 4500 5000 1000 1500 2000 2500 3000 3500 4000 4500 5000 Vault Size (Chaff Points) Vault Size (Chaff Points) PKA Communication Energy Consumption for Different Vault Sizes 0.4 PKA Computation/Communication Energy Ratio for Different Vault Sizes Sender 3 Receiver Sender(Radio ON) Sensing Sender(Radio OFF) 0.35 Receiver(Radio ON) Receiver(Radio OFF) 2.5 0.3 2 0.25 Energy (Joules) Ratio 1.5 0.2 0.15 1 0.1 0.5 0.05 1000 1500 2000 2500 3000 3500 4000 4500 5000 Vault Size (Chaff Points) 0 1000 1500 2000 2500 3000 3500 4000 4500 5000 Vault Size (Chaff Points) Green and Sustainable Cyber-Physical Security Solutions for Body Area Networks SENDER RECEIVER Mote EEG Radio-On Es ~ Er FFT Values PKA Power Profile (Radio-ON, Vault Size = 5000) FFT FFT Values Radio-On Es ~ Er FFT 0.06 current draw from processor exec. time current drawn from processor exec. Index Index Sensing 0.05 Sensors Sensing EKG current drawn by other components Oscilloscope BP Receiver(Radio ON) Peak Values 0.04 Peak Detection + Quantization Radio-Off Es << Er Sender(Radio ON) Peak Values Peak Detection + Quantization time current drawn by other components (Executing PKA) 0.03 Index SpO2 Radio-Off Es << Er Index Esense >> Es 0.02 Base Station Fs = [fs1 fs2 …….. fsn] Feature Gen supply voltage current draw from processor idle. Fr = [fr1 fr2 …….. frn] p(fs1) 2.7 ohms time current drawn from processor idle Krishna K. Venkatasubramanian, Ayan Banerjee, Sandeep K. S. GuptaDepartment of Computer Science and Engineering, Arizona State University Feature Gen p(fs2) 0.01 1 2 3 4 5 6 7 Lagrangian 8 9 Poly Gen + Vault Tx/Rx FFT Peak + Quant Ackn Tx/Rx Sensing Add Chaff p(fsn) Interpolation Eval (Measures current pulses and duty cycle) Base Station Polynomial Generation and evaluation fs1 fsn fs2 Environmental sensors Physiological sensors PKA Power Profile (Radio-OFF, Vault Size = 5000) Activity sensors 0.06 Receiver(Radio OFF) 0.05 Receive Vault Adding Chaff Motion Sensor Sender(Radio OFF) Radio-On Sender & Rec. (Ratio= ~2.5 – 1.5) 0.04 Multi-meter Power (mW) 0.03 1. Introduction 2. Security in Body Area Networks: Need and Approach 3. PKA: Physiological signal based Key Agreement Lagrangian Interpolation Transmit Vault current draw for each Tx. time current drawn for each Tx. 0.02 Radio-Off Rec. (Ratio ~ 1) (Ammeter) p(x) current drawn with transceiver off 0.01 Radio-On Esense << Es < Er • Need: • BANs collect sensitive medical data • Legal Requirement (HIPAA) • Potential for exploitation - Loss of privacy, Physical harm • Possible Attacks: • Fake warnings & resource wastage • Prevent legitimate warnings. • Unnecessary Actuations. • Security Requirements: • Integrity • Confidentiality • Authentication • Plug-n-Play 0 Ecomp, Ecomm comparable 1 2 3 4 5 6 7 8 9 FFT Peak + Quant Sensing Add Chaff Vault Tx/Rx Lagrangian Poly Gen + Ackn Tx/Rx Radio-Off Sender (Ratio ~ 0.1) Interpolation Eval time current drawn when transceiver off Receive Acknowledgement PKA Stages Transmit Acknowledgement PRIMARY ISSUE Secure Inter- Sensor Communication in BAN supply voltage current draw for each Rx time current drawn for each Rx • Solution: • Cyber-physical Solution • Tightly coupled with their environment- the human body • Require many signal processing and mathematical routines • Example - Physiological signal based Key Agreement (PKA). 6. Energy Model 4. Problem Statement 5. Energy Measurement • Security adds overhead. • Energy analysis for security primitives important • Analyze PKA’s energy-footprint to: • Evaluate its total energy cost • Cost of its individual components • Evaluate if it can be powered in a plug-n-play manner using energy scavenging techniques Computational Model • PKA executed on a pair of TelosB motes. • Across the two power leads of the mote, 2.7 ohm resistance was connected in series with an Ammeter. • An oscilloscope was connected across the resistance to measure duty cycle. • Each stage of PKA is executed in 2 modes– Radio Off/On Communication Model 7. Power Profile 9. Energy Scavenging Energy Measurement Setup MAX Power Needed = 58mW • Scavenging model: • “On-the-fly” consumption • No storage • Minimal User Involvement • Scavenging Techniques: 8. Energy Results 10. Conclusions • Security adds overhead. Energy analysis for security primitives important. Here we analyzed its energy-footprint: • To evaluate its energy cost • To show if it can be powered in a plug-n-play manner • Communication power is comparable with computation power • The max power required by PKA low enough to be sustained by prominent energy scavenging techniques Max Power 58mW http://impact.asu.edu sandeep.gupta@asu.edu