In this paper, we propose a novel method for two communicates to exchange a secret over a public wireless fading channel. Unlike conventional computationally secure public key methods, this technique is information theoretic and unconditionally secure provided that a component of the reciprocal channel fading over time between the two communicates is statistically independent with the channel fading from either communicate to the eavesdropper. This technique may be particularly well suited to secure tactical mobile communications. A simple protocol suitable for a lognormal shadowed fading channel is described and its key exchange rate is derived.
In this paper, we propose a novel method for two communicates to exchange a secret over a public wireless fading channel. Unlike conventional computationally secure public key methods, this technique is information theoretic and unconditionally secure provided that a component of the reciprocal channel fading over time between the two communicates is statistically independent with the channel fading from either communicate to the eavesdropper. This technique may be particularly well suited to secure tactical mobile communications. A simple protocol suitable for a lognormal shadowed fading channel is described and its key exchange rate is derived.
This paper considers the transmission of confidential data over wireless channels. Based on an information-theoretic formulation of the problem, in which two legitimates partners communicate over a quasi-static fading channel and an eavesdropper observes their transmissions through a second independent quasi-static fading channel, the important role of fading is characterized in terms of average secure communication rates and outage probability. Based on the insights from this analysis, a practical secure communication protocol is developed, which uses a four-step procedure to ensure wireless information-theoretic security: (i) common randomness via opportunistic transmission, (ii) message reconciliation, (iii) common key generation via privacy amplification, and (iv) message protection with a secret key. A reconciliation procedure based on multilevel coding and optimized low-density parity-check (LDPC) codes is introduced, which allows to achieve communication rates close to the fundamental security limits in several relevant instances. Finally, a set of metrics for assessing average secure key generation rates is established, and it is shown that the protocol is effective in secure key renewal—even in the presence of imperfect channel state information.
Due to the openness and broadcast nature of wireless mediums, wireless communication is always vulnerable to potential security threats such as eavesdropping, since unauthorized receiving is facilitated through wireless channels. This paper proposes a secret key negotiation scheme based on the difference of the packet loss. In a wireless channel, the packet losses at the intended receiver and the eavesdropper are statistically independent due to the independence of the thermal noise and the channel fading. The proposed scheme has exploited this feature in negotiating a secret key between Alice and Bob. Simulation results show that the proposed secret key negotiation scheme can effectively guarantee the security of wireless communications even if Eve is very close to Alice or Bob.
The multipath-rich wireless environment associated with typical wireless usage scenarios is characterized by a fading channel response that is time-varying, location-sensitive, and uniquely shared by a given transmitter–receiver pair. The complexity associated with a richly scattering environment implies that the shortterm fading process is inherently hard to predict and best modeled stochastically, with rapid decorrelation properties in space, time, and frequency. In this paper, we demonstrate how the channel state between a wireless transmitter and receiver can be used as the basis for building practical secret key generation protocols between two entities. We begin by presenting a scheme based on the “Reciprocity based key exchange model” allows two parties jointly establish physically secure key combined with a (standard) computationally secure key, over an insecure communication channel. This key can then be used to encrypt subsequent communications. The channel state between a wireless transmitter and receiver can be used as the basis for building practical secret key generation protocols between two entities. We validate both proposed protocols through experimentations using a customized 802.11a platform, and show for the typical Wi-Fi channel that reliable secret key establishment can be accomplished at rates on the order of 11 b/s.
Methods to generate private keys based on wireless channel characteristics have been proposed as an alternative to standard key-management schemes.In this paper, we discuss past work in the field and offer a generalized scheme for the generation of private keys using uncorrelated channels in multiple domains.Proposed cognitive enhancements measure channel coherence, to dynamically change transmission and reception parameters as well as estimate private key strength and expiration time.We evaluate a proof-of-concept implementation of this system in software using a channel model that provides variation in multiple domains. I. INTRODUCTIONFor a wireless communications link to be secure, it must provide data confidentiality and integrity during transmission.The principal method through which this is achieved is the use of cryptography, of which there are generally two types, public key [1] and private key [2].Public-key cryptography is a method for secret communication between two parties without the requirement of an initial exchange of secret keys.It employs a pair of keys, one private, which is held secret, and one public, which is distributed.Messages are encrypted with the recipient's public key and decrypted with the recipient's corresponding private key.Public-key cryptography is thus relatively unencumbered with key-exchange difficulties and key-interception vulnerabilities, however it is computationally intensive.Private-key cryptography is a method for secret communication between two parties that requires an initial exchange of a single shared secret key.Messages are encrypted by the sender and decrypted by the recipient using this same shared key.Private-key cryptography is less computationally intensive than public-key cryptography, however key distribution and management are problematic.Key distribution risks that the secret key will be intercepted during transmission.Key management requires the generation and transport of a different key for each communicating party [3].
Symmetric cryptography relies on pairs of identical secret keys shared by the legitimate communicating parties. To implement a symmetric-key algorithm for cryptography, a major concern is to develop secure methods for distribution of the secret key. In securing the wireless fading channels by symmetric-key algorithms, the physical layer properties of the channel can be exploited for distribution of the secret keys. In this approach, the channel state provides a common randomness which is shared by the legitimate users but is mostly unknown to an eavesdropper. by means of signal processing techniques, this common randomness is extracted into random secret keys. This paper establishes an information theoretic upper bound on the rate at which the secret keys can be extracted. Instead of the conventional approach that relies on mathematical models for the wireless channel, this paper adopts an experimental approach to estimate this bound from empirical data. A set of signal processing techniques is developed here to numerically estimate this bound for a pair of received signal strength (RSS) recorded by indoor commercial radios.
The multipath-rich wireless environment associated with typical wireless usage scenarios is characterized by a fading channel response that is time-varying, location-sensitive, and uniquely shared by a given transmitter-receiver pair. The complexity associated with a richly scattering environment implies that the short-term fading process is inherently hard to predict and best modeled stochastically, with rapid decorrelation properties in space, time, and frequency. In this paper, we demonstrate how the channel state between a wireless transmitter and receiver can be used as the basis for building practical secret key generation protocols between two entities. We begin by presenting a scheme based on level crossings of the fading process, which is well-suited for the Rayleigh and Rician fading models associated with a richly scattering environment. Our level crossing algorithm is simple, and incorporates a self-authenticating mechanism to prevent adversarial manipulation of message exchanges during the protocol. Since the level crossing algorithm is best suited for fading processes that exhibit symmetry in their underlying distribution, we present a second and more powerful approach that is suited for more general channel state distributions. This second approach is motivated by observations from quantizing jointly Gaussian processes, but exploits empirical measurements to set quantization boundaries and a heuristic log likelihood ratio estimate to achieve an improved secret key generation rate. We validate both proposed protocols through experimentations using a customized 802.11a platform, and show for the typical WiFi channel that reliable secret key establishment can be accomplished at rates on the order of 10 b/s.