this book constitutes the thoroughly refereed post-proceedings of the 8th international workshop on fast software encryption, fse 2001, held in yokohama, japan in april 2001.the 27 revised full papers presented together with one invited paper were carefully reviewed and selected from 46 submissions. the papers are organized in topical sections on cryptanalysis of block ciphers, hash functions and boolean functions, modes of operation, cryptanalysis of stream ciphers, pseudo-randomness, and design and evaluation.