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Collusion resistant broadcast encryption with short ciphertexts and private keys. (English) Zbl 1145.94434
Shoup, Victor (ed.), Advances in cryptology – CRYPTO 2005. 25th annual international cryptology conference, Santa Barbara, CA, USA, August 14–18, 2005. Proceedings. Berlin: Springer (ISBN 3-540-28114-2/pbk). Lecture Notes in Computer Science 3621, 258-275 (2005).
Summary: We describe two new public key broadcast encryption systems for stateless receivers. Both systems are fully secure against any number of colluders. In our first construction both ciphertexts and private keys are of constant size (only two group elements), for any subset of receivers. The public key size in this system is linear in the total number of receivers. Our second system is a generalization of the first that provides a tradeoff between ciphertext size and public key size. For example, we achieve a collusion resistant broadcast system for $$n$$ users where both ciphertexts and public keys are of size $$O(\sqrt n)$$ for any subset of receivers. We discuss several applications of these systems.
For the entire collection see [Zbl 1131.94006].

##### MSC:
 94A60 Cryptography 94A62 Authentication, digital signatures and secret sharing
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