Related key chosen IV attacks on Decim v2 and Decim-128
The Decim v1 is a hardware oriented stream cipher that was proposed by Berbain et al. and has been submitted to eSTREAM. Decim v2 is a revised version of Decim v1 and was submitted to ISO/IEC 18033-4. Decim-128 is a 128-bit security version of Decim. In this paper, we propose related key chosen IV attacks on Decim v2 and Decim-128. The attacks on Decim v2 and Decim-128 can recover the 80-bit and 128-bit secret keys with computational complexity of 2(68)/2(96), requiring 2(20)/2(51) chosen IVs, 2(26)/2(56.88)-bit stream sequence and negligible/2(42.58) bits space, respectively. When more than 8 and 10 related keys can be obtained for Decim v2 and Decim-128, the computational complexity can be reduced to 2(32)/2(38), requiring 2(23)/2(33.32) chosen IVs, 2(29)/2(39.25)-bit stream sequence and negligible/2(30.91) bits space, respectively. These results have been the best key recovery attacks on Decim v2 and Decim-128. (C) 2011 Elsevier Ltd. All rights reserved.
related key chosen iv attack decim v2 decim-128 stream cipher cryptanalysis