Bøger af Guang Gong

These are the proceedings of the Workshop on Sequences, Subsequences, and Consequences that was held at the University of Southern California (USC), May 31 - June 2, 2007. There were three one-hour Keynote lectures, 16 invited talks of up to 45 minutes each, and 1 "e;contributed"e; paper. The theory of sequences from discrete symbol alphabets has found practical applications in many areas of coded communications and in cryptography, - cluding: signal patterns for use in radar and sonar; spectral spreading sequences for CDMA wireless telephony; key streams for direct sequence stream-cipher cryptography; and a variety of forward-error-correctingcodes. The workshopwasdesigned to bring leading researcherson "e;sequences"e;from aroundtheworldtopresenttheirlatestresults,interchangeinformationwithone another, and especially to inform the larger audience of interested participants, includingfaculty,researchers,scholars,andstudentsfromnumerousinstitutions, as well as the readers of these proceedings, about recent developments in this important ?eld. There were invited speakers from Canada, China, Germany, India, Israel, Norway, Puerto Rico, and South Korea, in addition to those from the USA. Support for the workshop was generously provided by the O?ce of the Dean of the Viterbi School of Engineering, by the Center for Communications Research (CCR-La Jolla), and by the United States National Science Foundation (NSF). This support is hereby gratefully acknowledged.

This book constitutes the refereed proceedings of the 4th International Conference on Sequences and Their Applications, SETA 2006. The book presents 32 revised full papers together with 4 invited lectures. The papers are organized in topical sections on linear complexity of sequences, correlation of sequences, stream ciphers and transforms, topics in complexities of sequences, multi-sequence synthesis, sequences and combinatorics, FCSR sequences, aperiodic correlation and applications, and boolean functions, and more.

This book constitutes the thoroughly refereed post-proceedings of the 17th Annual International Workshop on Selected Areas in Cryptography, SAC 2010, held in Waterloo, Ontario, Canada in August 2010. The 24 revised full papers presented together with 2 invited papers were carefully reviewed and selected from 90 submissions. The papers are organized in topical sections on hash functions, stream ciphers, efficient implementations, coding and combinatorics, block ciphers, side channel attacks, and mathematical aspects.

Strong Pseudorandompermutations or SPRPs,which were introduced byLuby andRacko? [4], formalize the well established cryptographic notion ofblock ciphers.They provided a construction of SPRP, well known as LRconstruction, which was motivated by the structure of DES[6].The basicbuildingblock is the so called 2n-bit Feistel permutation (or LR round permutation) LR based F K on an n-bitpseudorandomfunction (PRF) F : K n LR (x ,x)=(F (x )?x ,x ),x ,x?{0,1} . F 1 2 K 1 2 1 1 2 K Theirconstruction consists (see Fig 1) offour rounds of Feistel permutations (or three rounds, for PRP), each round involves an application ofanindependent PRF(i.e.with independentrandomkeys K ,K ,K , and K ). More precisely, 1 2 3 4 LR and LR are PRP and SPRP respectively where K ,K ,K K ,K ,K ,K 1 2 3 1 2 3 4 LR := LR := LR (...(LR (·))...). K ,...,K F ,...,F F F 1 r K K K K r r 1 1 After this work, many results are known improvingperformance (reducingthe number of invocations of F )[5] and reducingthekey-sizes (i.e. reusingthe K roundkeys [7,8,10,12,11] orgenerate more keysfromsinglekey by usinga PRF[2]). However there are some limitations.Forexample,wecannotuseas few as single-keyLR (unless wetweak the roundpermutation) orasfew as two-roundsince they are not secure.Distinguishing attacks forsome other LR constructionsarealso known [8]. We list some oftheknow related results (see Table 1). Here all keys K ,K ,... are independently chosen.