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. 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. 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. 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. In this section, we will analyze the security of our proposed scheme. The main assumption for guarantee of security lies in:
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. ( ) Our framework combines µSTR and µTGDH protocols using strictly defined cover-path as part of the binary key tree (TFAN tree). However, this structural modification of the key tree leaves the actual computation process of the group key unchanged, i.e., it still relies on the tree-based ECDH key exchange method applied in µSTR and µTGDH. Therefore, the security analysis of µSTR and µTGDH from [10] is also valid for our framework. For completeness we briefly discuss how TFAN fulfills the security requirements causes the change of all secret keys in its path up to the root all secret keys that A knows get changed, and there- fore A is not able to compute the updated group key. Thus, forward secrecy is provided. As combination of backward and forward secrecy we follow that TFAN provides key in- dependence. Updated group keys are independent due to a random change of sponsor’s contribution. Since both proto- cols, µSTR and µTGDH, fulfill the verifiable trust require- ment our framework fulfills it too. Indeed, whenever a spon- sor Ms located in the cs-tree CTs at node ls, vs broad- casts a message containing the updated public keys, there is at least one other member that is able to verify the correct- ness of the sponsor’s message. In case of TFAN (art = S) the verification can be done by all members in CTs located at nodes l, v for all l > ls. In case of TFAN (art = T ) it can be done by a member located at the sponsor’s sibling node. Additionally in both cases the changed public keys of cover-nodes CNi for all i ≤ s can be verified by mem- bers in every cs-tree CTj with j > i.
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 , p, x mod p, and y mod p, it is infeasible for E to compute xy mod p) and the discrete logarithm problem (i.e., given only , p, and x mod p, it is infeasible for E to compute x). The following proof is based on [3], [15].
Security Analysis. In the proposed protocol, the agreed secret K and EK are dynamically generated in every session, furthermore, there is no decryption oracle for any fixed EK to help the adversary in the running of the protocol. Hence, we only require the one-time symmetric-key encryption scheme to be passively secure as defined in Definition 2. While, for the simplicity of security analysis, we specifically require that E is the “one time pad” with pseudorandom bit stream scheme, which is an efficient and passively secure one-time encryption scheme [18].
Security Analysis. In addition to provisioning of mutual “direct” authentica- tion [12], Xx et al.’s scheme fulfills all the security criteria as defined in Section 1.2 except KCI resilience and PrFS. Moreover, the scheme also protects the master secret (kHN) in the event of compromise of various nodes of the WBAN. For sake of brevity, we will restrict our security analysis to highlight only the vulnerabilities of Li et al.’s scheme.
