PKG forward secrecy Sample Clauses

PKG forward secrecy. To satisfy PKG forward secrecy, the compromise of master key of PKG1 and PKG2 must not affected the security of past session keys. The past session key can be computed if the corresponding partial ses- sion keys K(1) and K(2) can be computed. If we assume that adversary knows AB BA s(1), K(1) = e(1)(Q(1), P(1))as(1)b can be computed if the adversary can compute AB A e(1)(aQ(1), bP(1)), e(1)(bQ(1), aP(1)), e(1)(Q(1), abP(1)), or e(1)(abQ(1), P(1)). With-

PKG forward secrecy. Compromise of PKG master key does not reveal any information about session key because to achieve season key, the value (xU , xL) and (u, l) are needed, which can not be computed by using master key. Because, secret values (u, xU ) and (l, xL) are randomly generate by L and U respectively. Moreover, for given ⟨P, xU P, xLP⟩ and P, uP, lP computation of xLxU P and ulP are equivalent to CDH problem respectively. Known session-specific temporary information attack: If short term secret keys u and l are compromised, then session keys does not reveals. Because, with short term secret keys u and l and given information ⟨YU = xU mkP, YL = xLmkP, QU , QL⟩ one can achieve SU or SL as: e(uQL, YL) · e(lQU , YU ) = e(QL,P )xLmku · e(QU ,P )xU mkl ⟨ ⟩ However, to achieve sk = H(IDU ||IDL||luP||xLxU P||SL), the value xLxU P is needed, where for given P, xU P, xLP computation of xLxU P is equivalent to CDH problem.