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We put forward a new family of computational assumptions, the Kernel Matrix Diffie-Hellman Assumption. Given some matrix A sampled from some distribution D ,k , the kernel assumption says that it is hard to find " in the exponent " a nonzero vector in the kernel of A. This family is the natural computational analogue of the Matrix Decisional Diffie-Hellman(More)
At Crypto'99, Fujisaki and Okamoto [8] presented a nice generic transformation from weak asymmetric and symmetric schemes into an IND-CCA hybrid encryption scheme in the Random Oracle Model. Two specific candidates for standardization were designed from this transformation: PSEC-2 [14] and EPOC-2 [7], based on El Gamal and Okamoto-Uchiyama primitives,(More)
In a threshold broadcast encryption scheme, a sender chooses (ad-hoc) a set of n receivers and a threshold t, and then encrypts a message by using the public keys of all the receivers, in such a way that the original plaintext can be recovered only if at least t receivers cooperate. Previously proposed threshold broadcast encryption schemes have ciphertexts(More)
An attribute-based signature with respect to a signing policy , chosen ad-hoc by the signer, convinces the verifier that the signer holds a subset of attributes satisfying that signing policy. Ideally, the ver-ifier must obtain no other information about the identity of the signer or the attributes he holds. This primitive has many applications in real(More)
In a threshold broadcast encryption scheme, a sender chooses (ad-hoc) a set of n receivers and a threshold t, and then encrypts a message by using the public keys of all the receivers, in such a way that the original plaintext can be recovered only if at least t receivers cooperate. This kind of scheme has many applications in mobile ad-hoc networks,(More)