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Abstract : |
Abstract. This paper proposes two new public-key cryptosystems semantically secure against adaptive chosen-ciphertext attacks. Inspired from a recently discovered trapdoor technique based on composite-degree residues, our converted encryption schemes are proven, in the random oracle model, secure against active adversaries (IND-CCA2) under the assumptions that the Decision Composite Residuosity and Decision Partial Discrete Logarithms problems are intractable. We make use of specific techniques that di#er from Bellare-Rogaway or Fujisaki-Okamoto conversion methods. Our second scheme is specifically designed to be e#cient for decryption and could provide an elegant alternative to OAEP., |
