Efficient user removal in broadcast channel with symmetric encryption

Rok, strany: 2006, 1 - 14

We present a broadcast protocol that enables to remove some receivers by updating a key used for encrypting transmission. The scheme is based on a set of keys properly distributed among users. Our protocol requires relatively small transfer for updating the set of authorized users. In a system with $n$ users, our protocol requires $2 · c · łog_c{n}$ keys per user. To exclude $k$ users it needs to broadcast $2 · łog_c{n} · k$ symmetric ciphertext blocks. Our construction outperforms simple tree-like key designs and is a good alternative for polynomial-based protocols (like the one of Watanabe et al.) using asymmetric cryptography. Known polynomial-based protocols require a broadcast of length $O(k)$ for removing $k$ users. We get the same message size by setting $c = n^1/d$ for some constant $d$. It would result in giving $2 · n^1/d · d$ keys to each user. If users are able to store so many keys, then our protocol appears to be useful since it requires much less computation time and is better if we want to update the set of users quite often.

ISO 690:

Byrka, J. 2006. Efficient user removal in broadcast channel with symmetric encryption. In Tatra Mountains Mathematical Publications, vol. 33, no.1, pp. 1-14. 1210-3195.

APA:

Byrka, J. (2006). Efficient user removal in broadcast channel with symmetric encryption. Tatra Mountains Mathematical Publications, 33(1), 1-14. 1210-3195.