2012 | OriginalPaper | Chapter
3kf9: Enhancing 3GPP-MAC beyond the Birthday Bound
Authors : Liting Zhang, Wenling Wu, Han Sui, Peng Wang
Published in: Advances in Cryptology – ASIACRYPT 2012
Publisher: Springer Berlin Heidelberg
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Among various cryptographic schemes, CBC-based MACs belong to the few ones most widely used in practice. Such MACs iterate a blockcipher
E
K
in the so called Cipher-Block-Chaining way, i.e.
C
i
=
E
K
(
M
i
⊕
C
i
− 1
) , offering high efficiency in practical applications. In the paper, we propose a new deterministic variant of CBC-based MACs that is provably secure beyond the birthday bound. The new MAC 3kf9 is obtained by combining
f
9 (3GPP-MAC) and EMAC sharing the same internal structure, and so it is almost as efficient as the original CBC MAC. 3kf9 offers
$O(\frac{l^3q^3}{2^{2n}}+\frac{lq}{2^n})$
PRF-security when its underlying
n
-bit blockcipher is pseudorandom with three independent keys. This makes it more secure than traditional CBC-based MACs, especially when they are applied with lightweight blockciphers. Therefore, 3kf9 is expected to be a possible candidate MAC in resource-restricted environments.