# Collusion Resistant Broadcast Encryption With Short Ciphertexts and Private Keys

**Authors:**

*D. Boneh, C. Gentry, and B. Waters*

** Abstract: **

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), no matter what
the subset of receivers is. 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.

** Reference:**

In proceedings of Crypto '05, LNCS 3621, pp. 258-275, 2005

**Full paper:**
pdf
[first posted
2/2005 ]