Passive Wi-Fi is a technology to generate 802.11b transmissions using backscatter communication, with power consumption 10000× lower than existing Wi-Fi chipsets. Since wearable devices are typically limited in resources such as power and storage, classical cryptographic security schemes are problematic for them. We instead propose to use wireless channel characteristics to secure data transfer. It has been shown that communicating wireless transceivers are able to generate shared secret keys by measuring channel characteristics at a single frequency. These methods are not applicable to passive Wi-Fi, which uses two different frequencies. In this paper, we describe a method to generate a shared secret key based on wireless channel characteristics in the passive Wi-Fi scenario where the two parties are using dual frequencies.
Passive Wi-Fi is a technology to generate 802.11b transmissions using backscatter communication, with power consumption 10000× lower than existing Wi-Fi chipsets. Since wearable devices are typically limited in resources such as power and storage, classical cryptographic security schemes are problematic for them. We instead propose to use wireless channel characteristics to secure data transfer. It has been shown that communicating wireless transceivers are able to generate shared secret keys by measuring channel characteristics at a single frequency. These methods are not applicable to passive Wi-Fi, which uses two different frequencies. In this paper, we describe a method to generate a shared secret key based on wireless channel characteristics in the passive Wi-Fi scenario where the two parties are using dual frequencies.
Secure wireless communications is a challenging problem due to the shared nature of the wireless medium. Most existing security protocols apply cryptographic techniques for bit scrambling at the application layer by exploiting a shared secret key between pairs of communicating nodes. However, more recent research argues that multipath propagation - a salient feature of wireless channels - provides a physical resource for secure communications. In this context, we propose a protocol that exploits the inherent randomness in multipath wireless channels for generating secret keys through channel estimation and quantization. Our approach is particularly attractive in wideband channels which exhibit a large number of statistically independent degrees of freedom (DoF), thereby enabling the generation of large, more-secure, keys. We show that the resulting keys are distinct for distinct pairwise links with a probability that increases exponentially with the key-size/channel DoF. We also characterize the probability that the two users sharing a common link generate the same key. This characterization is used to analyze the energy consumption in successful acquisition of a secret key by the two users. For a given key size, our results show that there is an optimum transmit power, and an optimum quantization strategy, that minimizes the energy consumption. The proposed approach to secret key generation through channel quantization also obviates the problem of key pre-distribution inherent to many existing cryptographic approaches.
Secret key generation based on channel characteristics is an effective physical-layer security method for 5G wireless networks. The issues of how to ensure the high key generation rate and correlation of the secret key under active attack are needed to be addressed. In this paper, a new practical secret key generation scheme with high rate and correlation is proposed. In our proposed scheme, Alice and Bob transmit independent random sequences instead of known training sequences or probing signals; neither Alice nor Bob can decode these random sequences or estimate the channel. User's random sequences together with the channel effects are used as common random source to generate the secret key. With this solution, legitimate users are able to share secret keys with sufficient length and high security under active attack. We evaluate the proposed scheme through both analytic and simulation studies. The results show that our proposed scheme achieves high key generation rate and key security, and is suitable for 5G wireless networks with resource-constrained devices.
Due to the broadcast nature of wireless channels, wireless communication is vulnerable to eavesdropping, message modification, and node impersonation. Securing the wireless communication requires the shared secret keys between the communicating entities. Traditional security schemes rely on public key infrastructures and cryptographic algorithms to manage secret keys. Recently, many physical-layer-based methods have been proposed as alternative solutions for key generation in wireless networks. These methods exploit the inherent randomness of the wireless fading channel to generate secret keys while providing information-theoretical security without intensive cryptographic computations. This article provides an overview of the existing PHY-based key generation schemes exploiting the randomness of the wireless channels. Specifically, we first introduce the fundamental and general framework of the PHY-based key generation schemes and then categorize them into two classes: received-signal-strength-based and channel- phase-based protocols. Finally, we present a performance comparison of them in terms of key disagreement probability, key generation rate, key bit randomness, scalability, and implementation issues.
Reliable communication over Wireless Body Area Networks (WBANs) is an essential aspect of Wireless Body Area Networks (WBANs) because the physiological data flows between wearable sensor nodes is sensitive data. The convectional cryptography methods usually apply a lot of computational complexity as well as energy overhead besides which they are not going to fit in the ultra-low-power WBANs. In the current paper a light-weight, energy-efficient Physical Layer Key Generation (PLKG) scheme the possibilities of which based on the native randomness and reciprocity of the wireless channel is used to generate secure symmetric keys is presented. With WBANs, there is a lot of temporal and spatial dynamics in the human body and its surrounding environment, which causes great variability in channel characteristics, in terms of Received Signal Strength Indicator (RSSI) and Channel State Information (CSI). Such physical layer parameters can be used as perfect entropy sources in generation of unique, unpredictable secret keys with whose knowledge, communication between nodes is possible and mutually exclusive only. The channel probing in the proposed framework is also robust, multi-bit quantization is performed adaptively, information reconciliation is performed through error correction codes, and privacy amplification is made through cryptographic hashing. We have developed a resilient system against bit mismatch and efficiently against passively eavesdropping, we guarantee the secrecy of the generated keys under adversary situation. With realistic WBAN models simulation and experiment validation shows that the proposed approach is capable of generating keystokes with very high key generation rate (50 bps) and a bit mismatch rate of lower than 3 percent as compared to existing schemes that solely relied on RSSI, making this protocol more secure and reliable to use. In addition, the framework meets the statistical randomness requirements specified by NIST and it does not leak mutual information to eavesdroppers. The scheme allows real-time use on resource-constrained devices, e.g., wearable medical devices and health-monitoring sensor, as it has low computational and memory overhead. The findings establish the feasibility of employing physical layer properties to achieve secure WBANs communication without any pre-shared keys or a centralized trust paradigm, thus, opening the way to scalable and privacy-preserving healthcare systems.
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].
Secure communication in a wireless environment is very vital, and cryptographic schemes are usually used to ensure it. Secret keys that are unknown to the tappers are needed by cryptographic schemes to secure communication between two legitimate users. In recent years the secret key generation scheme that utilizes a wireless channel as a secret key generation source has become a very interesting and promising topic. The main problem of this scheme is the high wireless channel mismatch between two users due to nonsimultaneous measurements and noise from the device. In this paper, we proposed a secret key generation scheme that uses the Savitzky-Golay filter method to reduce the high mismatch wireless channel. The scheme that was built was also equipped with a multibit quantization method to increase the speed of generation of secret keys. The results of our tests show a decrease in wireless channel mismatch between two users and an increase in the speed of generation of secret keys.