To establish secure (point-to-point and or broadcast) communication channels among the nodes of a wireless sensor network is a fundamental task. To this end, a plethora of (socalled) key pre-distribution schemes have been proposed in the past. All these schemes, however, rely on shared secret(s), which are assumed to be somehow pre-loaded onto the sensor nodes. In this paper, we propose a novel method for secure initialization of sensor nodes based on a visual out-of-band channel. Using the proposed method, the administrator of a sensor network can distribute keys onto the sensor nodes, necessary to bootstrap key pre-distribution. Our secure initialization method requires only a little extra cost, is efficient and scalable with respect to the number of sensor nodes. Moreover, based on a usability study that we conducted, the method turns out to be quite user-friendly and easy to use by naive human users.
@cite_16 proposed a new scheme based on visual OOB channel. The scheme uses one of the protocols based on Short Authenticated Strings (SAS) @cite_6 , @cite_4 , and is aimed at pairing two devices (such as a cell phone and an access point), only one of which has a relevant receiver (such as a camera). The protocol is depicted in Figure and as we will see in the next section, this is the protocol that we utilize in our proposal. In this paper, we extend the above scheme to a many-to-one'' setting applicable to key distribution in sensor networks. Basically, the novel OOB channel that we build consists of multiple devices blinking their SAS data simultaneously, which is captured using a camera connected to the sink.
@cite_16 @cite_4 @cite_6
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Initiating and bootstrapping secure, yet low-cost, ad-hoc transactions is an important challenge that needs to be overcome if the promise of mobile and pervasive computing is to be fulfilled. For example, mobile payment applications would benefit from the ability to pair devices securely without resorting to conventional mechanisms such as shared secrets, a Public Key Infrastructure (PKI), or trusted third parties. A number of methods have been proposed for doing this based on the use of a secondary out-of-band (OOB) channel that either authenticates information passed over the normal communication channel or otherwise establishes an authenticated shared secret which can be used for subsequent secure communication. A key element of the success of these methods is dependent on the performance and effectiveness of the OOB channel, which usually depends on people performing certain critical tasks correctly. In this paper, we present the results of a comparative usability study on methods that propose using humans to implement the OOB channel and argue that most of these proposals fail to take into account factors that may seriously harm the security and usability of a protocol. Our work builds on previous research in the usability of pairing methods and the accompanying recommendations for designing user interfaces that minimise human mistakes. Our findings show that the traditional methods of comparing and typing short strings into mobile devices are still preferable despite claims that new methods are more usable and secure, and that user interface design alone is not sufficient in mitigating human mistakes in OOB channels. Due to the publicly-known deterministic character- istic of pilot tones, pilot-aware attack, by jamming, nulling and spoofing pilot tones, can significantly paralyze the uplink channel training in large-scale MISO-OFDM systems. To solve this, we in this paper develop an independence-checking coding based (ICCB) uplink training architecture for one-ring scattering scenarios allowing for uniform linear arrays (ULA) deployment. Here, we not only insert randomized pilots on subcarriers for channel impulse response (CIR) estimation, but also diversify and encode subcarrier activation patterns (SAPs) to convey those pilots simultaneously. The coded SAPs, though interfered by arbitrary unknown SAPs in wireless environment, are qualified to be reliably identified and decoded into the original pilots by checking the hidden channel independence existing in sub- carriers. Specifically, an independence-checking coding (ICC) theory is formulated to support the encoding decoding process in this architecture. The optimal ICC code is further devel- oped for guaranteeing a well-imposed estimation of CIR while maximizing the code rate. Based on this code, the identification error probability (IEP) is characterized to evaluate the reliability of this architecture. Interestingly, we discover the principle of IEP reduction by exploiting the array spatial correlation, and prove that zero- IEP, i.e., perfect reliability, can be guaranteed under continuously-distributed mean angle of arrival (AoA). Besides this, a novel closed form of IEP expression is derived in discretely-distributed case. Simulation results finally verify the effectiveness of the proposed architecture. Abstract In this paper, a novel error control scheme using Fountain codes is proposed in on–off keying (OOK) based visible light communications (VLC) systems. By using Fountain codes, feedback information is needed to be sent back to the transmitter only when transmitted messages are successfully recovered. Therefore improved transmission efficiency, reduced protocol complexity and relative little wireless link-layer delay are gained. By employing scrambling techniques and complementing symbols, the least complemented symbols are needed to support arbitrary dimming target values, and the value of entropy of encoded message are increased. This paper presents a new pairing protocol that allows twoCPU-constrained wireless devices Alice and Bob to establish ashared secret at a very low cost. To our knowledge, this is thefirst software pairing scheme that does not rely on expensivepublic-key cryptography, out-of-band channels (such as a keyboardor a display) or specific hardware, making it inexpensive andsuitable for CPU-constrained devices such as sensors. In the described protocol, Alice can send the secret bit 1 toBob by broadcasting an (empty) packet with the source field set toAlice. Similarly, Alice can send the secret bit 0 to Bob bybroadcasting an (empty) packet with the source field set to Bob.Only Bob can identify the real source of the packet (since it didnot send it, the source is Alice), and can recover the secret bit(1 if the source is set to Alice or 0 otherwise). An eavesdroppercannot retrieve the secret bit since it cannot figure out whetherthe packet was actually sent by Alice or Bob. By randomlygenerating n such packets Alice and Bob can agree on ann-bit secret key. Our scheme requires that the devices being paired, Alice andBob, are shaken during the key exchange protocol. This is toguarantee that an eavesdropper cannot identify the packets sent byAlice from those sent by Bob using data from the RSSI (ReceivedSignal Strength Indicator) registers available in commercialwireless cards. The proposed protocol works with off-the-shelf802.11 wireless cards and is secure against eavesdropping attacksthat use power analysis. It requires, however, some firmwarechanges to protect against attacks that attempt to identify thesource of packets from their transmission frequency.