Paper 2007/292
Improved security analysis of OMAC
Mridul Nandi
Abstract
We present an improved security analysis of OMAC, the construction is widely used as a candidate of MAC or Pseudo Random Function (or PRF). In this direction, the first result was given in Crypto05 where an improved security analysis of CBC (for fixed length or for arbitrary length prefixfree messages) had provided. Followed by this work, improved bounds for XCBC, TMAC and PMAC were found. The improved bounds are of the form $\mathrm{O}(\frac{Lq^2}{2^n})$ where the original bounds are $\mathrm{O}(\frac{\sigma^2}{2^n})$ which is roughly $\mathrm{O}(\frac{L^2q^2}{2^n})$. Here, a distinguisher can make at most $q$ queries having at most $\sigma$ many blocks with $L$ as the maximum block size. The original bound for OMAC was roughly $\frac{5L^2q^2}{2^n}$ shown in FSE03 and the next improved bound was $\frac{4\sigma^2}{2^n}$ shown in Indocrypt03. In this paper we have provided an improved bound (a similar form as provided for others) for OMAC and the bound we show is roughly $\frac{4q\sigma}{2^n} = \mathrm{O}(\frac{Lq^2}{2^n})$.
Metadata
 Available format(s)
 Category
 Secretkey cryptography
 Publication info
 Published elsewhere. Unknown where it was published
 Contact author(s)
 mridul nandi @ gmail com
 History
 20070807: received
 Short URL
 https://ia.cr/2007/292
 License

CC BY
BibTeX
@misc{cryptoeprint:2007/292, author = {Mridul Nandi}, title = {Improved security analysis of OMAC}, howpublished = {Cryptology ePrint Archive, Paper 2007/292}, year = {2007}, note = {\url{https://eprint.iacr.org/2007/292}}, url = {https://eprint.iacr.org/2007/292} }