Security Analysis. 4.2.1. Session Key Security Xx uses the session key to encrypt the information sending over Internet. Therefore, if the session key is secure, it means that the communication in the cloud meeting is also security. The proposed solution has the Diffie–Xxxxxxx problem. Even if attackers capture Tai (x) or Tbi (x), they still can not generate authentication information. Moreover, we consider random value ai and bi, so it is difficult for attackers to compute ski and SK = h(Sn, ski). Therefore, the session key is security in PL-GAKA.
Security Analysis. A A A A A In our scheme, an adversary is able to manipulate locally- stored temporary states, reject to provide the correct proof, and refuse to make a revocation. The goal of is to get profit by tempering or canceling state transitions. We focus on the most important attack, dependency attack, where first submits commitments about TX1 with user B colluding with , then makes another latency-first transaction TX2 with user U . tries to get profit by tempering or canceling TX2 by not providing the correct proof about TX1. A
Security Analysis. In this section, we will analyze the security of our proposed scheme. The main assumption for guarantee of security lies in:
Security Analysis. 5.1.1 Informal security analysis Theoretical security analysis The proposed authentication scheme provides a resistance to different possible attacks. In our analysis, we are interested in: • Replay attack: the replay attack can be dangerous for such a scheme. In fact, a replay attack occurs when an attacker intercepts a previous message exchanged by a sensor node, and tries to replay it in order to impersonate the sensor node, respectively the gateway node, or the remote user. For this reason, we must take seriously the
Security Analysis. This section provides the security analysis of the proposed scheme focused on no requirement of global time synchronization, providing forward secrecy provision, and secure against password guessing attack, replay attack and user identity guessing attack.
Security Analysis. An inherent problem with EKA is the length of the blocks it communicates during the commitment phase. As they are only 64 bits long, their hashes can be easily brute-forced by a capable adversary. One of the ways of overcoming this problem could be to use key strengthening. The main idea being that sensors hash each of their 64 bit blocks ’2n’ times before transmitting them. An attacker while brute forcing has to generate a candidate block (64 bits long) and hash it ’2n’ times before knowing weather the candidate is the actual block. Therefore an additive increase in the number of hash computations for the sender results in a multiplicative increase in the hashing requirements for the adversary. This results in a 2n fold increase in the processing required for brute- forcing a 64 bit block which is analogous to brute forcing a 64 + n bit block. We recommend that sensors choose the value of ’n’ as high as possible. However, key strengthening is an expensive proposition. The need to hash each of the 20 blocks 2n times increases the costs further. For example if we choose ’n’ to be 16 (which makes the block as secure as a 80 bit block) the total number of hash operations required to computed would be 131072!. The choice of this value actually used therefore, may depend upon the capabilities of the sensor and the amount of energy available at them, and hostility of the environment in which the subject carrying the sensors is. In a home environment for example, no key strengthening may be required, while in a shopping mall the maximum possible value of ’n’ would be necessary. The use of key strengthening is however a stop-gap solution, we are currently working on generating longer blocks during the commitment phase so that brute-forcing them becomes impractical. Assuming that the brute forcing of blocks is infeasible, the commitment and de-commitment phases makes it very difficult for adversaries to know the key being agreed upon. There are 4 reasons for this - a) The blocks are not exchanged 0.9985 0.998 Averag Entropy 0.9975 0.997 0.9965 . Σ
Security Analysis. This section provides security analysis focused on password guessing attack, replay attack, stolen-smart card attack and user anonymity.
Security Analysis. A-TGDH satisfies our stated security goals with the following assumptions. Since key confirmation is essential for achieving perfect forward secrecy [4], we assume that it has been implemented as described in Section V-B. Also, we assume that there exists only a passive adversary E that monitors the flow of blinded key messages. We further assume that E cannot solve the Xxxxxx-Xxxxxxx problem [6] (i.e., given only α, p, αx mod p, and αy mod p, it is infeasible for E to compute αxy mod p) and the discrete logarithm problem (i.e., given only α, p, and αx mod p, it is infeasible for E to compute x). The following proof is based on [3], [14].
Security Analysis. Theorem 2.1 shows that the Xxxxx-Xxxxxxxx IBC algorithm is a chosen ciphertext secure IBE (IND-ID-CCA) under some assumption. The results in [23] indicate that it is also a semantically secure identity based encryption scheme (IND-ID-CPA). Furthermore, in symmetric key system private keys are stored in at least two nodes, while in our scheme private keys are stored only in one node. This can enhance security level of sensor networks with IBE algorithms. In order to add new node in wireless sensor networks with symmetric key technique, some private keys have to be distributed to the new node. Also, some index information has to be changed in case a node is deleted. But in our scheme, based on IBE algorithms, adding or deleting a node does not affect other nodes, because only identities of nodes are used as public keys. The scheme is independent of network size. Moreover, it is easy to reach a time-stamped identity by using “xxx@company || 03” as a public key [24].
Security Analysis. Theorem 1. Let AdvP (t, qse, qh) be the maximum advantage in attacking P, where the max- imum is over all adversaries that run in time t, and make qse Send queries and qh random oracle queries. Then we have AdvP (t, qse, qh) ≤ 2 · SuccN (tj) + 2pu(k) · SuccΓ(tjj), where tj = t + O(qsepu(k)texp + qhtexp), tjj = t + O(qsepu(k)texp), and texp is the time required to compute a modular exponentiation in G. In the following we briefly outline the proof of Theorem 1. The proof is divided into two cases: (1) the case that the adversary A breaks the scheme by forging a signature with A F respect to some user’s public key, and (2) the case that breaks the scheme without forging a signature. We argue by contradiction, assuming that there exists an adversary who has a non-negligible advantage in attacking P . For the case (1), we reduce the security of scheme P to the security of the signature scheme Γ, by constructing an efficient forger who given as input a public key PK and access to a signing oracle associated with this key, outputs a valid forgery with respect to PK. For the case (2), the reduction is from the factoring problem; given the adversary A, we build an efficient factoring algorithm B which given as input N = p · q generated by FIG(1k), outputs either p or q.
