Towards black-box accountable authority IBE with short ciphertexts and private keys
(2009) Public Key Cryptography -PKC 2009. 12th International Conference on Practice and Theory in Public Key Cryptograph — Location: Irvine, CA, USA (18.March.2009)
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- Abstract
- 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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Citations
Libert, B., & Vergnaud, D. (2009). Towards black-box accountable authority IBE with short ciphertexts and private keys. Public Key Cryptography -PKC 2009. 12th International Conference on Practice and Theory in Public Key Cryptograph, p. 235-255. https://hdl.handle.net/2078.5/219049