Secure communication in Internet of Things (IoT) devices can be improved through physical-layer secret key generation. In secret key generation, an information reconciliation process is required to match the bit sequences between the two communicating devices. However, this process often involves complex statistical computations that increase system overhead and require the transmission of bits over an insecure public channel. Therefore, this research presents a lightweight reconciliation algorithm based on minimal bit syndrome to reduce overhead and improve key security. The proposed method processes quantized Received Signal Strength (RSS) values into 8-bit block syndrome-based reconciliation mechanism and only the 8-bit syndromes from mismatched block are transmitted over the public channel. System testing was conducted under both static and dynamic scenarios in an indoor area using Raspberry Pi nodes. The results show that the proposed scheme demonstrates an improvement in the Key Generation Rate (KGR) by 2.2% and reduces the processing time by 11.6% in dynamic scenario and 8.3% in the static scenario. Also, the proposed scheme reduce the quantization and reconciliation time by 50% compared to previous research. Furthermore, the proposed method maintained a Key Disagreement Rate (KDR) of 0% across all block size and successfully passed the NIST randomness and complexity test, with all test parameters achieving p-values above 0.01. These result indicate that the proposed scheme improve the performance of existing secret key generation methods and it is suitable for implementation in IoT devices.
Secure communication in Internet of Things (IoT) devices can be improved through physical-layer secret key generation. In secret key generation, an information reconciliation process is required to match the bit sequences between the two communicating devices. However, this process often involves complex statistical computations that increase system overhead and require the transmission of bits over an insecure public channel. Therefore, this research presents a lightweight reconciliation algorithm based on minimal bit syndrome to reduce overhead and improve key security. The proposed method processes quantized Received Signal Strength (RSS) values into 8-bit block syndrome-based reconciliation mechanism and only the 8-bit syndromes from mismatched block are transmitted over the public channel. System testing was conducted under both static and dynamic scenarios in an indoor area using Raspberry Pi nodes. The results show that the proposed scheme demonstrates an improvement in the Key Generation Rate (KGR) by 2.2% and reduces the processing time by 11.6% in dynamic scenario and 8.3% in the static scenario. Also, the proposed scheme reduce the quantization and reconciliation time by 50% compared to previous research. Furthermore, the proposed method maintained a Key Disagreement Rate (KDR) of 0% across all block size and successfully passed the NIST randomness and complexity test, with all test parameters achieving p-values above 0.01. These result indicate that the proposed scheme improve the performance of existing secret key generation methods and it is suitable for implementation in IoT devices.
In recent years, the Internet of Things (IoT) becomes popular technology. The one aspect that makes important concern in IoT is the confidentiality of communications. For securing communication in IoT, cryptography algorithm such as symmetrical cryptography requires the secret key exchange process in a public wireless network to ensure the sameness of the secret key. However, the exchange of secret keys in the public wireless network can be exploited by adversaries. So, we present the secret key generation scheme that generates a shared random key through observation of the communication channel parameter i.e. Receive Signal Strength (RSS) between two devices that no need to exchange the secret key. We use Middle-Point quantization to convert the RSS into bit sequences and use Clover Filter to eliminate the error bits after the quantization process. Measurement results showed that the proposed scheme improves the performance of existing schemes if the interval used is 25. The proposed scheme improves the KGR 24 times and improves efficiency to 63%. While for KDR, the proposed scheme can decrease the KDR value of 67.9%. Also, in all scenarios, the proposed scheme can pass the NIST randomness test.
In symmetric cryptography systems have problems in the distribution of secret keys. The two users who will communicate require sharing keys through the public channel. The proposed solution to overcome these problems is to utilize information from the physical layer (e.g. RSS). Received Signal Strength (RSS) is an indicator for measuring the power received by wireless devices. The advantage of secret key extraction using physical layer information from a wireless channel is that it allows both devices within the transmission range to extract the secret key together. In this paper, we propose a secret key generation scheme adopted from an existing scheme with modifications to improve performance. Our proposed system is applied to static and dynamic conditions to test performance. The proposed algorithm is able to obtain a reduction in KDR (Key Disagreement Rate) up to 48.42% and an increase in the KGR (Key Generation Rate) up to 23.35% when compared to the existing scheme. Our proposed system also successfully passed the randomness using the NIST test with the approximate value of entropy generated 0.80 in static conditions and 0.81 in dynamic conditions.
Devices in the Internet of Things (IoT) are usually limited in computing resources and energy capacity, which means that encryption schemes with higher complexity are not suitable for them to ensure secure communication. As a promising solution to this problem, physical layer key generation suggests that shared secret keys can be generated from noisy wireless channel measurements to enhance the security of wireless communications. In this article, we propose a key generation scheme with extremely low implementation complexity, which allows physical layer key generation to be implemented on IoT nodes. First, we preprocess the channel measurements with simple moving average filtering before quantization to improve channel reciprocity. Next, a bidirectional difference quantization scheme is proposed to realize reliable quantization of channel measurements, which is ingenious in that the quantization process does not depend on quantization thresholds, and thus, the mismatched key bits caused by measurements close to quantization thresholds can be effectively avoided. Then, we propose an improved Cascade protocol to achieve lightweight and efficient information reconciliation. The simulation results show that our scheme can well balance the reliability and efficiency of key generation, and has excellent performance in terms of implementation complexity and key randomness.
Received Signal Strength (RSS) is a parameter that is widely used in physical layer security systems because of its reciprocal and spatially decorrelated nature. However, RSS values fluctuate, so they require pre-processing before they can be used for reliable secret key generation. This study evaluates the effectiveness of combining Kalman filtering with two quantization methods, Jana multi-bit and multi-bit quantization, on the difference in signal strength (DOSS) data obtained from indoor environments. Testing is carried out by comparing the performance of the Key Generation Rate (KGR) and Key Disagreement Rate (KDR) as indicators of bitstream quality. The experimental results show that the combination of Kalman filtering and multi-bit quantization produces the best performance with a KDR as low as 1% and a KGR of 3.67 kbit/s. In contrast, the Jana multi-bit method without Kalman produces a higher KGR but with a much larger KDR. This finding confirms that quantization strategies-especially multi-bit ones-are critical in improving RSS-based bit quality even before the key generation stage is entirely performed.
For the future Internet of Things (IoT) with ubiquitous wireless connectivity, the physical layer secret key (PLSK) scheme has been recognized as an effective and lightweight way to achieve secure communications by exploiting the reciprocity of the wireless channel. Compared with channel state information (CSI)-based PLSK generation schemes, received signal strength (RSS)-based schemes are more advantageous in terms of the communication costs and mobility for the IoT applications. However, due to the vulnerability of predictable channel attacks, RSS-based schemes cannot always guarantee perfect security. In this paper, we combine angle of arrival (AoA) and received signal strength (RSS) to generate physical layer secret key (PLSK). In particular, we propose a novel measurement named effective key generation rate (EKGR) to comprehensively and directly evaluate a PLSK scheme. Meanwhile, we further simplify the conventional PLSK generation steps to meet the low-complexity demand of IoT devices. At last, numerical results demonstrate that comparing with RSS-based and AoA-based schemes, our proposed EKGR of the RSS-AoA-based scheme achieves 78% or even 120% performance improvement.
Modern networking technologies involve the interconnection of smart and intelligent physical objects to provide advanced services. These physical objects may be part of various network technologies like WLAN, wireless sensor network (WSN), Internet of Things (IoT), etc., and share data in wireless mode, which should be secured from threats. These physical devices possess many constraints like power, computational complexity and storage, and are required to have lightweight security algorithms. Traditionally, security is achieved by the higher layers of the communication model, which has high computational complexity and consumes more power. In this chapter, a secure-key-generation scheme from physical layer characteristics is introduced as a possible lightweight security alternative to traditional upper-layer security approaches. The proposed scheme is based on the wiretap-channel model and security is achieved by generating keys at both communicating ends independently, based on inherent common-channel characteristics like randomness. It is mainly based on the principle of spatial decorrelation and channel reciprocity for identical carrier frequency. There is no provision for sharing keys as in public-key cryptography, so physical-layer key generation is not vulnerable to threats like key leakage. The generated key at the transmitter encrypts plain text; the generated cipher is transmitted on the common channel and is decrypted at the receiver end using the key generated by the receiver. Key generation consists of fundamental blocks like channel probing and quantization followed by information reconciliation and privacy amplification. The physical-layer key generation is already a power-efficient security solution; this chapter aims to enhance this capacity further. This is done by introducing low-end signal conditioning in the channel-probing step using moving-window averaging. This solution not only improves system performance but also makes it suitable for limited- power applications. The performance of the key-generation system is characterised in terms of the bit-disagreement rate between the generated key sequences of communicating parties and the key randomness by means of the NIST statistical test suite.