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Secret Key Extraction from Wireless Signal Strength in Real Environments

Sriram N. PremnathSchool of Computing, University of Utah, Salt Lake, UT, USASuman JanaDepartment of Computer Science, University of Texas, Austin, Austin, TX, USAJessica CroftDepartment of Electrical and Computer Engineering, University of Utah, Salt Lake, UT, USAPrarthana Lakshmane GowdaSchool of Computing, University of Utah, Salt Lake, UT, USAMike ClarkUS Air Force Research Laboratory, Beavercreek, OH, USASneha Kumar KaseraSchool of Computing, University of Utah, Salt Lake, UT, USANeal PatwariDepartment of Electrical and Computer Engineering, University of Utah, Salt Lake, UT, USASrikanth V. KrishnamurthyDepartment of Computer Science and Engineering, University of California at Riverside, Riverside, CA, USA

2012en

ABI

Annotatsiya

We evaluate the effectiveness of secret key extraction, for private communication between two wireless devices, from the received signal strength (RSS) variations on the wireless channel between the two devices. We use real world measurements of RSS in a variety of environments and settings. The results from our experiments with 802.11-based laptops show that in certain environments, due to lack of variations in the wireless channel, the extracted bits have very low entropy making these bits unsuitable for a secret key, an adversary can cause predictable key generation in these static environments, and in dynamic scenarios where the two devices are mobile, and/or where there is a significant movement in the environment, high entropy bits are obtained fairly quickly. Building on the strengths of existing secret key extraction approaches, we develop an environment adaptive secret key generation scheme that uses an adaptive lossy quantizer in conjunction with Cascade-based information reconciliation and privacy amplification. Our measurements show that our scheme, in comparison to the existing ones that we evaluate, performs the best in terms of generating high entropy bits at a high bit rate. The secret key bit streams generated by our scheme also pass the randomness tests of the NIST test suite that we conduct. We also build and evaluate the performance of secret key extraction using small, low-power, hand-held devices-Google Nexus One phones-that are equipped 802.11 wireless network cards. Last, we evaluate secret key extraction in a multiple input multiple output (MIMO)-like sensor network testbed that we create using multiple TelosB sensor nodes. We find that our MIMO-like sensor environment produces prohibitively high bit mismatch, which we address using an iterative distillation stage that we add to the key extraction process. Ultimately, we show that the secret key generation rate is increased when multiple sensors are involved in the key extraction process.

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Identifikatorlar

DOI: 10.1109/tmc.2012.63

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