## CryptoDB

### Paper: CCA2-Secure Threshold Broadcast Encryption with Shorter Ciphertexts

Authors: Vanesa Daza Javier Herranz Carla Ràfols Paz Morillo URL: http://eprint.iacr.org/2007/127 Search ePrint Search Google 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},