Secret Key Extraction in Ultra Wideband Channels for Unsynchronized Radios

Abstract

Secure communications in UWB based on cryptographic keys generated from channel measurements without a trusted third party have been developed. The fine time resolution of UWB allows high levels of mutual information to be obtained by a given A and B through independent characterizations of their shared communication channel. This mutual information determines the maximum secret key rate available to A and B. Since UWB channel gains change drastically with small antenna movements, it is inherently difficult for eavesdroppers to obtain channel measurementsand reduce the secret key rate. In essence, UWB can provide spatial-temporal specific secret keys. Upper bounds on the secret key rate for standard UWB channels are calculated. It is demonstrated that high secure key generation rates are possible. It is shown that these key rates can be generated over a wide range of signal to noise ratios and channel synchronization errors.

Secret Key Generation and Agreement in UWB Communication Channels

“…Systems have been previously proposed for the use of UWB channel measurements for secret key generation [7]. However, it has been shown that these methods do not come close to obtaining all the available secret key bits from UWB channel impulse response measurements [8].…”

Practical limits of the secret key-capacity for IoT physical layer security

“…However these bounds are only theoretically possible and practically unattainable without using specialised equipment. The maximum size as well as generation of shared secret keys from the observation and processing of radio channel parameters have also been examined in [7], [12], [13], [14]. However the aforementioned works examine the subject either purely from a theoretical informational-theoretic perspective, or by performing the observations with specialised hardware.…”

Group Secret Key Generation via Received Signal Strength: Protocols, Achievable Rates, and Implementation

“…Sayeed et al use random phase for secret key extraction in an OFDM system [5], whereas Wang et al propose a scheme for efficient key establishment [6]. The impulse response of a wireless channel is used to generate a shared secret [4], [22], [23], [24]. Ultra-wideband radios are used to measure the impulse response [23], [24], while Mathur et al and Ye et al propose to estimate the impulse response from Wilar signals [4], [22], respectively.…”

“…The impulse response of a wireless channel is used to generate a shared secret [4], [22], [23], [24]. Ultra-wideband radios are used to measure the impulse response [23], [24], while Mathur et al and Ye et al propose to estimate the impulse response from Wilar signals [4], [22], respectively. Statistics of the angle-of-arrival (AOA) is used as a signature for key generation [2], however, it requires an access point to have a programmable phased array antenna received signal strength or channel gain is the most commonly used radio channel feature for secret key extraction due to it is readily available in existing wireless infrastructure, and thus it is easy to measure with little effort.…”

“…where (22) follows by dropping the vector notation, since observations are i.i.d., (23) follows by the application of chain rule on both terms of the right side of (22), (24) …”