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Communication Dans Un Congrès Année : 2009

Towards Black-Box Accountable Authority IBE with Short Ciphertexts and Private Keys

Résumé

At Crypto'07, Goyal introduced the concept of Accountable Authority Identity-Based Encryption as a convenient tool to reduce the amount of trust in authorities in Identity-Based Encryption. In this model, if the Private Key Generator (PKG) maliciously re-distributes users' decryption keys, it runs the risk of being caught and prosecuted. Goyal proposed two constructions: the first one is efficient but can only trace well-formed decryption keys to their source; the second one allows tracing obfuscated decryption boxes in a model (called weak black-box model) where cheating authorities have no decryption oracle. The latter scheme is unfortunately far less efficient in terms of decryption cost and ciphertext size. In this work, we propose a new construction that combines the efficiency of Goyal's first proposal with a very simple weak black-box tracing mechanism. Our scheme is described in the selective-ID model but readily extends to meet all security properties in the adaptive-ID sense, which is not known to be true for prior black-box schemes.
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Dates et versions

inria-00356999 , version 1 (29-01-2009)

Identifiants

  • HAL Id : inria-00356999 , version 1

Citer

Benoît Libert, Damien Vergnaud. Towards Black-Box Accountable Authority IBE with Short Ciphertexts and Private Keys. 12th International Conference on Practice and Theory in Public-Key Cryptography - PKC 2009, 2009, Irvine, United States. pp.235-255. ⟨inria-00356999⟩
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