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CCA2-Secure Threshold Broadcast Encryption with Shorter Ciphertexts
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Abstract: | 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 whose length is $\O(n)$. In this paper, we propose new schemes, for both PKI and identity-based scenarios, where the ciphertexts' length is $\O(n-t)$. The construction uses secret sharing techniques and the Canetti-Halevi-Katz transformation to achieve chosen-ciphertext security. The security of our schemes is formally proved under the Decisional Bilinear Diffie-Hellman (DBDH) Assumption. |
BibTeX
@misc{eprint-2007-13409, title={CCA2-Secure Threshold Broadcast Encryption with Shorter Ciphertexts}, booktitle={IACR Eprint archive}, keywords={cryptographic protocols / threshold broadcast encryption, ad-hoc groups, secret sharing}, url={http://eprint.iacr.org/2007/127}, note={ jherranz@iiia.csic.es 13607 received 4 Apr 2007}, author={Vanesa Daza and Javier Herranz and Carla Ràfols and Paz Morillo}, year=2007 }