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We put forward a new algebraic framework to generalize and analyze Diffie–Hellman like decisional assumptions which allows us to argue about security and applications by considering only algebraic properties. Our $$\mathcal {D}_{\ell ,k}\text{- }\textsf {MDDH}$$ D ℓ , k - MDDH Assumption states that it is hard to decide whether a vector in $$\mathbb(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)
Lossy trapdoor functions, introduced by Peikert and Waters (STOC'08), have received a lot of attention in the last years, because of their wide range of applications in theoretical cryptography. The notion has been recently extended to the identity-based scenario by Bellare et al. (Eurocrypt'12). We provide one more step in this direction, by considering(More)
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