Top PDF Design of OFDM Physical Layer Encryption Scheme

Design of OFDM Physical Layer Encryption Scheme

Design of OFDM Physical Layer Encryption Scheme

A. Search Space Search space is not the final parameter describing the computational complexity for the brute force attack, which also depends on the computation overhead required for each round of the attack. As PLE schemes protect the data at different modulation stages, the eavesdropper may carry out part of the receiving procedure and then be faced to decrypt the data, as illustrated in Fig. 5. When the training symbol is unchanged, the eavesdroppers can detect the signal arrival and only need to store one complete received waveform. The eavesdropper then can carry out part of the receiving procedure and search for the right key. For example, for modulation symbols rotation-based schemes, the eavesdropper can perform the procedure as far as to the FFT operation then it will be faced to guess the correct angle for each constellation symbol. Conventional XOR encryption happens at the first stage of the physical layer modulation by XOR-ing the source binary data with key sequence so it does not randomize the transmitted waveform, thus the eavesdropper can perform the entire re- ceiving procedure. However, in our scheme, due to the training symbol resequencing, the eavesdropper is not able to perform synchronization and channel estimation correctly, he/she will then have to store all of the received signal waveform, and be always required to repeat the entire receiving procedure when trying each possible key sequence. This significantly increases the computational overhead for the eavesdropper. However, it is difficult to quantize the number of the computational operations for each round of the attack, therefore, we still use search space to analyze the security level of the system as it provides a quantitative description of numbers of the attempts required.
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Physical Layer Signal Design and Control For Wireless Security.

Physical Layer Signal Design and Control For Wireless Security.

Our work is related to anti-jamming and MIMO based interference cancellation techniques. In [14], Aryafar et al. designed and implemented a multi-user beam-forming system and an experimental MIMO framework for wireless LANs. The Interference Alignment and Can- cellation (IAC) technique was proposed in [34] to enable collaborative Access Points (APs) in MIMO LANs to decode more packets by controlling transmitted signals with proper vectors. In SAM [81], Tan et al. proposed a chain-decoding scheme which uses interference nullifying and cancellation to decode concurrent frames. It requires all stations to coordinate their trans- missions so that the chain-decoding can be achieved. 802.11n + [46] proposed to use “antidote” signals to nullify the transmitted signals from other nodes in order to enable multiple access to wireless channels. All these three schemes require nodes to coordinate their transmissions so that the receiver can obtain the sender’s channel coefficients, which makes them unsuitable for anti-jamming purpose. TIMO [31] reported techniques which exploits the channel ratio of the interference source to remove cross-technology interference for 802.11n. However, it requires that the receiver knows the channel information of the transmitter, which is not feasible under fast reactive jamming attack.
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Underwater Acoustic Communications: Design Considerations on the Physical Layer

Underwater Acoustic Communications: Design Considerations on the Physical Layer

Another way to save the energy is by minimizing the number of retransmissions. In random access networks, which are suitable for serving a varying number of users that transmit in a bursty manner, this task is made difficult by high channel latency. For example, the basic principle of carrier sensing multiple access – that a node should transmit only if it hears no on-going transmissions – is compromised in an acoustic channel where the packets propagate slowly, and the fact that none are overheard does not mean that some are not present in the channel. Multiple access with collision avoidance (MACA) has been used in the early acoustic network trials [17], and a number of variants have since been proposed [18], [19]. A different approach has been sought through the design of coordinated sleeping schedules for underwater nodes [20], [21]. Apart from the protocol design, it must be kept in mind that selection of power and bit rate will influence its performance: reducing the power reduces the level of interference; increasing the bit rate makes the packets shorter and reduces the chances of collision. Low speed of sound further challenges the throughput efficiency of any data link control scheme that requires automatic repeat request (ARQ), because current technology supports only half-duplex opera- tion. Careful consideration of the physical layer parameters can help to design data packets so as to take maximal advantage of limited resources [22]. The implications on routing protocols are similarly important.
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Physical Layer Security in Wireless Networks: Design and Enhancement.

Physical Layer Security in Wireless Networks: Design and Enhancement.

considered, in which the relay selects the strongest source-relay link to receive the signal and the strongest relay-destination link to forward the signal. Wireless Sensor Networks: In wireless sensor networks (WSNs), the sensed data is usually sensitive, and therefore secure transmission is critical in WSNs. Physical layer security has been recently introduced in WSNs to combat eavesdropping [54–57]. In [54], the downlink secure transmission from the mobile agent to the authorized user was considered and two randomized array transmission schemes were developed. In [55], Dis- tributed detection under secrecy constraint in an energy-constrained WSN was addressed, and the optimal operative solutions were analyzed. In [56], sensor transmissions were observed by the authorized fusion center (FC) and unauthorized (third party) FC. It was shown in [56] that the proposed security scheme at physical layer is highly scalable with low-complexity, compared to the traditional network security protocols such as cryptography and key management at the link and network layer. More recently in [57], AF compressed sensing (CS) was introduced to provide secrecy against eavesdropping in WSNs, and it was confirmed that the eavesdroppers cannot successfully decode the signal when the number of eavesdropper is less than the sparsity level of the signal.
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Artificial-noise-aided physical layer phase challenge-response authentication for practical OFDM transmission

Artificial-noise-aided physical layer phase challenge-response authentication for practical OFDM transmission

Recently, we have developed a PHYsical layer Phase Challenge-Response Authentication Scheme (PHY-PCRAS) for independent multicarrier transmission. In this paper, we make a further step by proposing a novel artificial-noise-aided PHY-PCRAS (ANA-PHY-PCRAS) for practical orthogonal fre- quency division multiplexing (OFDM) transmission, where the Tikhonov-distributed artificial noise is introduced to interfere with the phase-modulated key for resisting potential key-recovery attacks whenever a static channel between two legitimate users is unfortunately encountered. Then, we address various practical issues for ANA-PHY-PCRAS with OFDM transmission, including correlation among subchannels, imperfect carrier and timing recoveries. Among them, we show that the effect of sampling offset is very significant and a search procedure in the frequency domain should be incorporated for verification. With practical OFDM transmission, the number of uncorrelated subchannels is often not sufficient. Hence, we employ a time-separated approach for allocating enough subchannels and a modified ANA-PHY-PCRAS is proposed to alleviate the discontinuity of channel phase at far-separated time slots. Finally, the key equivocation is derived for the worst case scenario. We conclude that the enhanced security of ANA-PHY-PCRAS comes from the uncertainty of both the wireless channel
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A Novel Physical Layer Secure Key Generation and Refreshment Scheme for Wireless Sensor Networks

A Novel Physical Layer Secure Key Generation and Refreshment Scheme for Wireless Sensor Networks

ABSTRACT Physical Layer Secure Key Generation (PL-SKG) schemes have received a lot of attention from the wireless security community in recent years because of the potential benefits that they could bring to the security landscape. These schemes aim to strengthen current security protocols by reducing the amount of key material that devices need for deployment. They do this by harnessing the common source of randomness provided by the wireless channel that the physical layer is communicating over. This is of particular importance in Wireless Sensor Networks (WSNs) where resources are particularly scarce and where issues such as key revocation and recovery make the design of efficient key management schemes extremely difficult. This paper discusses the issues and challenges encountered in the design and implementation of PL-SKG schemes on off-the-shelf wireless sensor networks. It then proposes a novel key generation scheme that takes advantage of both the power and simplicity of classic error correcting codes and also the diversity of frequency channels available on 802.15.4 compliant nodes to generate keys from received signal strength (RSS) readings. This paper shows that our key generation and refreshment scheme can achieve a near 100% key reconciliation rate whilst also providing perfect forward and backward security.
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Research and Design of Security Scheme on Application Layer of a Web of Things

Research and Design of Security Scheme on Application Layer of a Web of Things

In addition to the use of visual cipher program [12], the use of symmetric encryption algorithm and MAC message verification code, in contrast, the authentication efficiency is relatively high. Literature [13] uses the public key to update the image key in the scheme, and this scheme only re-generates the random grid to achieve the key update, and the program in the calculation of cost also decreased. Compared with the literature [14], the two schemes use the random number generator, but the literature [14] uses the message verification code to verify the message, and this program uses the random number N to achieve the verification function to ensure that the message has not been tampered with, which is more efficient.
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A Novel Physical Layer Key Generation and Authenticated Encryption Protocol Exploiting Shared Randomness

A Novel Physical Layer Key Generation and Authenticated Encryption Protocol Exploiting Shared Randomness

In virtually all wireless communication technologies, security issues have been handled at the upper layer of the protocol stack using variations of private and public keys cryp- tography often referred to as computational security. This uses practical cryptographic approaches which are built to achieve semantic security, i.e., to withstand polynomial time chosen plaintext attacks. Such schemes really on the (unproven) intractability of certain hard problems typically involving the use of large prime numbers [11] [12]. For such scheme to work the existence of a shared source of entropy that can be accessed by the legitimate communicating node and inaccessible by an attacker is required and the entropy of this source should be sufficient to support computational complexity proof. In protocols in which the keys are used only once, this source of randomness is necessary for continuous update of the symmetric key. On the other hand if the keys are used multiple times, this source of randomness is used to update complementary parameters, such as initialization vectors (IVs), nonces of the particular enciphering scheme used. Despite the success of computationally security, their use is limited in some emerging wireless network architectures. As an example, the distribution of secret keys between legitimate communicating node in a wireless network requires some infrastructures for it to be car- ried it out. A solution to this is the use of a public key infrastructure (PKI) mechanism (e.g Diffie Hellman) in the presence of a certificate authority (CA), however in a dynamic mobile environment, it difficult and impractical to ensure the availability of a CA [13][14]. It is therefore imperative to have other alternatives for establishing secret key for secure wireless communication without resulting to a fixed infrastructure.
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A Novel Physical Layer Secure Key Generation and Refreshment Scheme for Wireless Sensor Networks

A Novel Physical Layer Secure Key Generation and Refreshment Scheme for Wireless Sensor Networks

ABSTRACT Physical Layer Secure Key Generation (PL-SKG) schemes have received a lot of attention from the wireless security community in recent years because of the potential benefits that they could bring to the security landscape. These schemes aim to strengthen current security protocols by reducing the amount of key material that devices need for deployment. They do this by harnessing the common source of randomness provided by the wireless channel that the physical layer is communicating over. This is of particular importance in Wireless Sensor Networks (WSNs) where resources are particularly scarce and where issues such as key revocation and recovery make the design of efficient key management schemes extremely difficult. This paper discusses the issues and challenges encountered in the design and implementation of PL-SKG schemes on off-the-shelf wireless sensor networks. It then proposes a novel key generation scheme that takes advantage of both the power and simplicity of classic error correcting codes and also the diversity of frequency channels available on 802.15.4 compliant nodes to generate keys from received signal strength (RSS) readings. This paper shows that our key generation and refreshment scheme can achieve a near 100% key reconciliation rate whilst also providing perfect forward and backward security.
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A Case for Cross Layer Design: The Impact of Physical Layer Properties on Routing Protocol Performance in MANETs

A Case for Cross Layer Design: The Impact of Physical Layer Properties on Routing Protocol Performance in MANETs

Compared to this ideal scenario the results obtained in the free space propagation scenario with constant and lognormal shadowing effects are significantly lower (around 3585.8 bits/sec and 3427.2 bits/sec respectively) in without cross layer design while it increases (around 3777.9 bits/sec and 3916.7 bits/sec respectively) in with cross layer design. There is almost a 10% difference in performance between the ideal scenario and the free space with lognormal shadowing model in without cross layer design while in case of cross layer design its almost 8%. A similar trend is observed using the two-ray ground reflection model as well. The difference between the ideal scenario and the worst case scenario (Two Ray with lognormal shadowing) is more than 20%. This drastic reduction in performance does not bode well for the scheme in real world deployments. Similar trends are observed across all protocols and across the three metrics (with some exceptions). Further these results are without including additional factors that will affect the quality of the signal that is received such as fading effects and weather conditions. It is our observation that the main reason for this drastic difference in performance is the use of inefficient path metrics (such as hop count or distance) in the calculation of best routes to a certain destination that’s why the current surge in cross-layer design activity is motivated by the inability of the architecture to accommodate wireless links satisfactorily.
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Physical-layer encryption on the public internet: A stochastic approach to the Kish-Sethuraman cipher

Physical-layer encryption on the public internet: A stochastic approach to the Kish-Sethuraman cipher

The first truly unbreakable cipher was the one-time-pad 1 , invented in the United States in 1918, but independently developed and first put into practice by the German Foreign Office in the early 1920s 2 . This scheme, however, is hampered by the need to distribute a key to receiver of the message. This key must be of the same size as the message and delivered in perfect secrecy. This onerous key distribution arrangement ruled it out for all but the most critical applications.

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Adaptive OFDM-IM for Enhancing Physical Layer Security and Spectral Efficiency of Future Wireless Networks

Adaptive OFDM-IM for Enhancing Physical Layer Security and Spectral Efficiency of Future Wireless Networks

It should be noted that the proposed scheme is a type of scheme which does not cause much difference in the SNR between Bob and Eve, but still Eve cannot decode, while Bob can decode (this case is somehow similar to the case of interleaver or precoder based security techniques [20, 30]). In such cases, BER can be used as a metric to measure secrecy instead of secrecy capacity and secrecy outage probability as reported in [20, 30, 31]. Therefore, in this work, we use BER-based secrecy gap metric [20] to evaluate the secrecy. Furthermore, in this work we are targeting quality of service (QoS) based security [16, 32]. The basic idea behind QoS based security is to secure different services (voice, video, etc.) instead of focusing on providing perfect secrecy. More specifically, it should be noted that perfect secrecy is not always needed to provide a perfectly secure service. In reality, each service has different QoS requirements than the others, and if we ensure that Eve is operating below these requirements, then practical secrecy can be guaranteed. So, in this work we target to provide security for services such as voice and video and make sure that error rate at Eve is greater than minimum required error rate criteria to use that service [16]. For example, voice and video can be made secure at Bob by making sure that PER (corresponding to BER) at Bob is less than minimum required PER (corresponding to BER) in order to use that service while PER at Eve is made greater than minimum required PER. The minimum PER requirement for different services is presented in Table 5 [26]. Hence, although the throughput is nonzero, the proposed scheme can still provide QoS based security (it should be noted that PER can be calculated from BER as follows: 𝑃𝐸𝑅 = 1 − (1 − 𝐵𝐸𝑅) 𝑛 ), where 𝑛 is the block size [33]).
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A downlink non orthogonal multiple access scheme having physical layer security

A downlink non orthogonal multiple access scheme having physical layer security

However, in wireless communication environments where a large number of terminals exist in an assumed 5G scenario, and a large amount of information is simul- taneously exchanged, wireless security for each transmis- sion is equally important. In other words, it is important to ensure confidentiality by encryption to prevent infor- mation from leaking to third parties and eavesdroppers during wireless transmissions. In current communica- tion systems, upper layer encryption protocols such as public key cryptography are mainly used. However, the enhancement of encryption properties only in the upper layer often leads to protocol complications and an in- crease in calculation complexity. Therefore, ensuring the integrity of wireless communication only in the upper layer is not desirable, but a similar approach in the phys- ical layer where the modulated signal is encrypted is also effective. The physical layer encryption can enhance se- curity protocols when it is concurrently used with the upper layer encryption, or can, otherwise, simplify the upper layer security protocol. As with regards to physical layer security schemes, we have proposed a chaos multiple-input multiple-output (C-MIMO) transmission method, which has both the functionality of encrypted modulation and channel coding, for exploiting the principle of chaos communications [7]. In this method, Gaussian modulated signals are generated from chaos signals correlated with transmission bits in a short block, and these signals are transmitted by MIMO spatial mul- tiplexing. A chaos signal is irregular and unpredictable, but its behavior is deterministically controlled by the ini- tial chaos value. By taking advantage of this feature, the initial chaos value can be used as a signal key shared by
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Cross-layer Design for Wireless Mesh Networks with Advanced Physical and Network Layer Techniques

Cross-layer Design for Wireless Mesh Networks with Advanced Physical and Network Layer Techniques

load, our system activation time refers to the period of time (seconds) the network would take to deliver all the sessions. It should be noted that the lower bound on the system activation time is equivalent to the upper bound of the network throughput. While network architecture traditionally adopts layering to network coordi- nation, where each layer controls a subset of the decision variables, and classically observes a subset of constant parameters and the variables from other layers [23], considering separated modules for each task and allowing the modules to communi- cate only with their adjacent modules is not efficient especially in wireless network designs. For instance, adjusting the resource allocation in the physical layer changes the average link rates, influences the optimal routing, and alters the achievable net- work throughput [62]. Therefore, by jointly designing mechanisms based on which physical-layer resource allocations, link scheduling and routing the traffic, is a ne- cessity for recent network protocols [29, 69, 112]. While designing a layered scheme is intuitively scalable, however, optimization in a cross-layer framework is sophisti- cated and requires advanced optimization techniques [76, 137]. Hence, our modeling throughout this thesis will follow the cross-layer approach that has been widely used in designing and studying the performance of wireless networks.
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Design and implementation of an OFDMA TDD physical layer for WiMAX applications

Design and implementation of an OFDMA TDD physical layer for WiMAX applications

The encoder in a tail-biting scheme has a complexity similar to that of a zero-tail encoder. The encoder was implemented adding a CP to each FEC block with a size equal to the constraint length of the shift register (in the case of mobile WiMAX, this value is seven). The decoder has a higher complexity because the starting state of the trellis is unknown before decoding. Maximum likelihood (ML) decoding achieves optimum performance, but it requires decoding the received block starting with all the possible initial states, which increases decoding complex- ity to unacceptable levels [36]. The implemented channel decoding process uses a suboptimal technique which pro- vides a good compromise between decoding quality and complexity, where the first bits of the block are appended after the block, and the last bits at the beginning of the block [37]. The size of the chunks added at the beginning and at the end of the blocks is equal to the traceback length configured in the Viterbi decoder. If a block is shorter than the traceback length, it is just sent three times to the decoder and only the output corresponding to the second repetition is taken into account.
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System design of the physical layer for Loon’s high altitude platform

System design of the physical layer for Loon’s high altitude platform

An experimental configuration where the Loon eNB employed spatial diversity instead of polarization diver- sity was also tested. In this experiment, the transmit antennas were placed ~ 1 m apart with the same polar- ization. From the theory presented in [12], the antennas should have been spaced further apart. However, the pro- totype Loon platform limitations restricted the spacing that could be achieved. Figure 14 also shows the CDF of this experiment. It can be seen that polarization diversity is significantly better than this particular configuration of spatial diversity. In addition, neither diversity scheme is sufficient for MIMO communication to a large num- ber of UEs. It is expected that improving antenna gain and tweaking the ECC at the eNB will improve this sit- uation. However, even with this improvement, we expect the MIMO performance from a HAP platform at lower frequencies to be worse than what is seen in a terrestrial network.
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Implementation of OFDM Encryption and a New Frequency Hopping System

Implementation of OFDM Encryption and a New Frequency Hopping System

Another OFDM related security given in [14] demonstrated a two-way authentication method between two OFDM devices. In fact, it uses the inherent physical features of the multi-path fading channel as signature for the message transmission. The OFDM re- lated security given in [40] illustrates a encryption method by inserting dummy data to randomly reserved subcarriers to mix up OFDM subcarriers, which randomizes waveform. The dummy data and subcarriers’ location are secrete info for transceiver which are gen- erated by pre shared information. Furthermore, the OFDM security method given in [1] shows that the OFDM encryption can be done by hiding certain synchronization infor- mation based on a pre-shared secret key sequence. In paper [1], it mentioned that their security scheme is resistant to multipath fading and impulsive noise.
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Cryptographic Primitives and Design Frameworks of Physical Layer Encryption for Wireless Communications

Cryptographic Primitives and Design Frameworks of Physical Layer Encryption for Wireless Communications

out, including multi-antenna beamforming [3]–[5], artifi- cial noise techniques [6]–[9], and cooperative interference techniques [10], to name but a few. Over the last two decades, researchers have developed a significant number of mathe- matical theories, technologies, algorithms, and solutions for information theory based PHY-security challenges. Based on information theory, PLS is designed to achieve security through secure coding which does not require keys. The prob- lem faced by PLS is that it depends on the channel. When the security capacity is zero, that is, the eavesdropping channel is better than the legal channel, or if the eavesdropping chan- nel is unknown, security cannot be guaranteed. Therefore, it is necessary to find other ways to enhance security at the physical layer.
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A novel physical layer scheme based on superposition codes

A novel physical layer scheme based on superposition codes

Synchronism is the underlying design principles of the PHY layer of today’s LTE-A radio access network [22]; thus, novel synchronization solutions for the future 5G service architecture will be really useful. On this pur- pose, thinking about SC codes as a novel method for both modulation and coding, at least for the inner code, an interesting perspective is to develop joint algorithm for decoding and channel parameter synchronization to be applied to schemes like the ones in [31, 32].

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A Secure Approach with Physical Layer Encryption in MANET

A Secure Approach with Physical Layer Encryption in MANET

Abstract — Establishing correct and efficient routes is an important design issue in mobile ad hoc networks (MANETs), a more challenging goal is to provide secured routing, because ad hoc environment is accessible to both legitimate network users and malicious attackers. Moreover, as the wireless links are highly error prone and providing security is still a critical task. Generally, security in this type of network is provided by interference of signals, which is not energy efficient. Physical layer security has been considered to provide confidentiality against eavesdropping. Shift difference algorithm has been proposed to transfer the data securely over the network. It converts the data into noise for transmission. Network traffic has been reduced, as only intended participants transmit the data. By default network layer security has been provided by encryption.
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