11 research outputs found
Channel-based key generation for encrypted body-worn wireless sensor networks
Body-worn sensor networks are important for rescue-workers, medical and many other applications. Sensitive data are often transmitted over such a network, motivating the need for encryption. Body-worn sensor networks are deployed in conditions where the wireless communication channel varies dramatically due to fading and shadowing, which is considered a disadvantage for communication. Interestingly, these channel variations can be employed to extract a common encryption key at both sides of the link. Legitimate users share a unique physical channel and the variations thereof provide data series on both sides of the link, with highly correlated values. An eavesdropper, however, does not share this physical channel and cannot extract the same information when intercepting the signals. This paper documents a practical wearable communication system implementing channel-based key generation, including an implementation and a measurement campaign comprising indoor as well as outdoor measurements. The results provide insight into the performance of channel-based key generation in realistic practical conditions. Employing a process known as key reconciliation, error free keys are generated in all tested scenarios. The key-generation system is computationally simple and therefore compatible with the low-power micro controllers and low-data rate transmissions commonly used in wireless sensor networks
How to Test the Randomness from the Wireless Channel for Security?
We revisit the traditional framework of wireless secret key generation, where
two parties leverage the wireless channel randomness to establish a secret key.
The essence in the framework is to quantify channel randomness into bit
sequences for key generation. Conducting randomness tests on such bit sequences
has been a common practice to provide the confidence to validate whether they
are random. Interestingly, despite different settings in the tests, existing
studies interpret the results the same: passing tests means that the bit
sequences are indeed random.
In this paper, we investigate how to properly test the wireless channel
randomness to ensure enough security strength and key generation efficiency. In
particular, we define an adversary model that leverages the imperfect
randomness of the wireless channel to search the generated key, and create a
guideline to set up randomness testing and privacy amplification to eliminate
security loss and achieve efficient key generation rate. We use theoretical
analysis and comprehensive experiments to reveal that common practice misuses
randomness testing and privacy amplification: (i) no security insurance of key
strength, (ii) low efficiency of key generation rate. After revision by our
guideline, security loss can be eliminated and key generation rate can be
increased significantly
Channel-based key generation for encrypted body-worn wireless sensor networks
Body-worn sensor networks are important for rescue-workers, medical and many other applications. Sensitive data are often transmitted over such a network, motivating the need for encryption. Body-worn sensor networks are deployed in conditions where the wireless communication channel varies dramatically due to fading and shadowing, which is considered a disadvantage for communication. Interestingly, these channel variations can be employed to extract a common encryption key at both sides of the link. Legitimate users share a unique physical channel and the variations thereof provide data series on both sides of the link, with highly correlated values. An eavesdropper, however, does not share this physical channel and cannot extract the same information when intercepting the signals. This paper documents a practical wearable communication system implementing channel-based key generation, including an implementation and a measurement campaign comprising indoor as well as outdoor measurements. The results provide insight into the performance of channel-based key generation in realistic practical conditions. Employing a process known as key reconciliation, error free keys are generated in all tested scenarios. The key-generation system is computationally simple and therefore compatible with the low-power micro controllers and low-data rate transmissions commonly used in wireless sensor networks
The Effect of Eavesdropper's Statistics in Experimental Wireless Secret-Key Generation
This paper investigates the role of the eavesdropper's statistics in the
implementation of a practical secret-key generation system. We carefully
conduct the information-theoretic analysis of a secret-key generation system
from wireless channel gains measured with software-defined radios. In
particular, we show that it is inaccurate to assume that the eavesdropper gets
no information because of decorrelation with distance. We also provide a bound
for the achievable secret-key rate in the finite key-length regime that takes
into account the presence of correlated eavesdropper's observations. We
evaluate this bound with our experimental gain measurements to show that
operating with a finite number of samples incurs a loss in secret-key rate on
the order of 20%.Comment: Submitted to the IEEE Transactions on Information Forensics and
Securit
CSI-based versus RSS-based Secret-Key Generation under Correlated Eavesdropping
Physical-layer security (PLS) has the potential to strongly enhance the
overall system security as an alternative to or in combination with
conventional cryptographic primitives usually implemented at higher network
layers. Secret-key generation relying on wireless channel reciprocity is an
interesting solution as it can be efficiently implemented at the physical layer
of emerging wireless communication networks, while providing
information-theoretic security guarantees. In this paper, we investigate and
compare the secret-key capacity based on the sampling of the entire complex
channel state information (CSI) or only its envelope, the received signal
strength (RSS). Moreover, as opposed to previous works, we take into account
the fact that the eavesdropper's observations might be correlated and we
consider the high signal-to-noise ratio (SNR) regime where we can find simple
analytical expressions for the secret-key capacity. As already found in
previous works, we find that RSS-based secret-key generation is heavily
penalized as compared to CSI-based systems. At high SNR, we are able to
precisely and simply quantify this penalty: a halved pre-log factor and a
constant penalty of about 0.69 bit, which disappears as Eve's channel gets
highly correlated
Finite-Block-Length Analysis in Classical and Quantum Information Theory
Coding technology is used in several information processing tasks. In
particular, when noise during transmission disturbs communications, coding
technology is employed to protect the information. However, there are two types
of coding technology: coding in classical information theory and coding in
quantum information theory. Although the physical media used to transmit
information ultimately obey quantum mechanics, we need to choose the type of
coding depending on the kind of information device, classical or quantum, that
is being used. In both branches of information theory, there are many elegant
theoretical results under the ideal assumption that an infinitely large system
is available. In a realistic situation, we need to account for finite size
effects. The present paper reviews finite size effects in classical and quantum
information theory with respect to various topics, including applied aspects
Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey
This paper provides a comprehensive review of the domain of physical layer
security in multiuser wireless networks. The essential premise of
physical-layer security is to enable the exchange of confidential messages over
a wireless medium in the presence of unauthorized eavesdroppers without relying
on higher-layer encryption. This can be achieved primarily in two ways: without
the need for a secret key by intelligently designing transmit coding
strategies, or by exploiting the wireless communication medium to develop
secret keys over public channels. The survey begins with an overview of the
foundations dating back to the pioneering work of Shannon and Wyner on
information-theoretic security. We then describe the evolution of secure
transmission strategies from point-to-point channels to multiple-antenna
systems, followed by generalizations to multiuser broadcast, multiple-access,
interference, and relay networks. Secret-key generation and establishment
protocols based on physical layer mechanisms are subsequently covered.
Approaches for secrecy based on channel coding design are then examined, along
with a description of inter-disciplinary approaches based on game theory and
stochastic geometry. The associated problem of physical-layer message
authentication is also introduced briefly. The survey concludes with
observations on potential research directions in this area.Comment: 23 pages, 10 figures, 303 refs. arXiv admin note: text overlap with
arXiv:1303.1609 by other authors. IEEE Communications Surveys and Tutorials,
201