Small Discussion Sample Clauses

Small Discussion. AMP passes four messages between Xxxxx and Xxx who agree on g(x+e)y while AMPn agreed on gxy. The password le compromise still needs memory dump and its analysis for getting &. The existence of e is explicit against a compromise of both. For example, if Xxx sends (&+ )x to Bob, then Bob will respond with (g xg )y and compute computable by 2 . Due to the existence of e, Xxx cannot compute from , x, e = (g xge)y = g( x+e)y. If e does not exist, will be equal to g xy so that it will be (x+1) 1 x and g y

Small Discussion. One can easily see that message 1 is extracted from PAK while message 2 and session key are motivated by AMP. This protocol performs simple computation in three passes and works in the augmented model where τC is defined as γ′, ν . For efficiency, it would be better to hash m when we compute β and w, say β = (mγ′gh(m))y and w = u−1(x + h(m)) mod q for a strong one-way hash function h( ). For more efficiency, we recommend to use a secure prime for TP-AMP. Security and efficiency of the proposed protocol will be discussed in Section 4. / In the legitimate protocol run, gx and νy are assumed not to be trivial values such as 0 and 1 as in the Xxxxxx-Xxxxxxx relatives. We need to define a failure count that must be manipulated by the server and increased by one when k2 = k2′ . The server should abort further requests of the client if the (subsequent) failure count exceeds its pre-defined limit, δ. This is a standard technique for resisting on-line guessing attacks. We also need to define the special function called ACCEPTABLE(·) since the server should abort when it returns false upon receiving ⟨C, m⟩. An example of the function follows: ACCEPTABLE(·) INPUT: ⟨C, m⟩ OUTPUT: Return false if C is being served by another instance; /* See Section 3 */ else if the failure count of C is greater than or equal to its limit δ; else if q|m; /* Check if m /∈ Zp∗ only when hashing m before raising g */ Return true otherwise; ∈ | Note that the first condition (for resisting the many-to-many guessing attacks in the next section) can be considered in very flexible ways, for example, an IP address instead of C, and can be substituted by a more effective way in the future. This function is valid for authentication sessions only. Note also that q m means q divides m, but it might be enough to assure m Zp∗ only when we hash m for β and w in the protocol.