3kf9: enhancing 3GPP-MAC beyond the birthday bound

  • Authors:

  • Liting Zhang;Wenling Wu;Han Sui;Peng Wang

  • Affiliations:

  • Institute of Information Engineering, Chinese Academy of Sciences, China;State Key Laboratory of Information Security, Institute of Software, Chinese Academy of Sciences, China;Institute of Information Engineering, Chinese Academy of Sciences, China;Institute of Information Engineering, Chinese Academy of Sciences, China

  • Venue:
  • ASIACRYPT'12 Proceedings of the 18th international conference on The Theory and Application of Cryptology and Information Security
  • Year:
  • 2012

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Abstract

Among various cryptographic schemes, CBC-based MACs belong to the few ones most widely used in practice. Such MACs iterate a blockcipher EK in the so called Cipher-Block-Chaining way, i.e. Ci=EK(Mi⊕Ci−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 f9 (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.