Daniele Micciancio Oded Regev Worst-Case to Average-Case Reductions Based on Gaussian Measures. 267-302 2007 37 SIAM J. Comput. 1 http://dx.doi.org/10.1137/S0097539705447360 db/journals/siamcomp/siamcomp37.html#MicciancioR07