This scheme has a limitation on the number of authentications, so that after reaching www.selleckchem.com/products/BIBW2992.html N authentications, a process restart is required. In addition, it is vulnerable to an opponent who sends small challenge values to users that respond with the Inhibitors,Modulators,Libraries chain initial values [9]. many This attack can be referred to as a small challenge attack. Also, the users are charged Inhibitors,Modulators,Libraries with computational processes through the initialization phase, which makes the system unsuitable for WSNs.2.2. Bicakci et al.��s SchemeThe infinite length hash chains (ILHC) proposed by [10] use a public-key algorithm, A, to produce a forward and infinite one way function (OWF). Bicakci et al. utilized RSA [11], where d is the private key and e is the public key.

The OTP originating from initial input ��s�� using the RSA public-key algorithm for the i-th authentication is:ki(s)=Ai(s,d)(4)and the verification of the i-th key is done Inhibitors,Modulators,Libraries by:ki?1(s)=A???(ki,e)(5)increasing the number of cascaded exponentiations Inhibitors,Modulators,Libraries increases the computational complexity, making this algorithm very difficult to implement in limited computation devices [12].2.3. Chinese Remainder Theorem (CRT)If the integers n1, n2,��,nk are pair-wise relatively prime, then the system of simultaneous congruence:x��r1?mod?n1x��r2?mod?n2?x��rk?mod?nk(6)has a unique solution: x=��i=1kriNi?1Ni?mod?N where;N=��i=1kni(7)Ni=Nni(8)Ni?1Ni��1?mod?ni(9)2.4. TESLA Family Broadcast AuthenticationTimed Efficient Stream Loss-tolerant Authentication (TESLA) [3] is a multicast stream authentication protocol.

Keys used to authenticate the i-th message is disclosed along with (i + 1)-th message.

��TESLA [4] provides authentication for data broadcasts, and requires that base station and sensor nodes be loosely time synchronized. According to Lamport��s scheme, a base station (BS) randomly selects the last key kn, the chain seed, and applies Inhibitors,Modulators,Libraries a one-way public function Inhibitors,Modulators,Libraries h(?) to generate the rest of keys: k0, k1,…, kn?1 as ki = h(ki+1). Given ki, every sensor node can generate the sequence k0, k1, …, kn?1. However, given ki, no one can generate ki+1. At i-th time slot, BS sends an authenticated Inhibitors,Modulators,Libraries message MACki Inhibitors,Modulators,Libraries (message). Sensor nodes store the message till the verification key in the (i + 1)-th time slot is Carfilzomib disclosed.

Sensor nodes verify disclosed key ki+1 by check FAQ using key ki as ki = h(ki+1). In ��TESLA, nodes are required to store a message until the authentication key is disclosed. This operation may create storage problems, and encourages DoS Anacetrapib types of attacks.��TESLA has been expanded to Multi-level ��TESLA [4] by simplifying the key distribution phase and introducing a new concept of a multi-level key chain generation using selleck chem pseudo-random functions that improves the protocol efficiency.