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Báo cáo hóa học: "Research Article An Efficient Objective Intelligibility Measure for Frequency Domain Scramblers"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article An Efficient Objective Intelligibility Measure for Frequency Domain Scramblers | Hindawi Publishing Corporation EURASIP Journal on Information Security Volume 2007 Article ID 32028 4 pages doi 10.1155 2007 32028 Research Article An Efficient Objective Intelligibility Measure for Frequency Domain Scramblers A. M. C. R. Borzino 1 J. A. Apolinario Jr. 1 and D. G. da Silva2 1 Department of Electrical Engineering Military Institute of Engineering IME Praẹa General Tibúrcio 80 22290-270 Rio de Janeiro RJ Brazil 2 Center for Telecommunications Studies CETUC Pontifical Catholic University of Rio de Janeiro PUC-Rio Rua Marques de Sao Vicente 225 22453-900 Rio de Janeiro RJ Brazil Correspondence should be addressed to J. A. Apolinário Jr. apolin@ime.eb.br Received 17 August 2007 Accepted 3 December 2007 Recommended by E. Magli An objective performance measure is proposed to evaluate the intelligibility of a speech signal having its frequency subbands permuted. The proposed tool can be used to generate efficient keys for frequency domain scramblers as well as to assess the results of cryptanalysis. Copyright 2007 A. M. C. R. Borzino et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION The main goal of a scrambler is to make a speech signal unintelligible via the permutation of its frequency subbands. In this work we assume a sampling frequency of 8 kHz and a filter bank with 8 channels each using a filter with 128 coefficients. With N being the number of permutable subbands there are N possible permutations. However not all of them are efficient 1 this is due to the fact that some of them result in a signal with high residual intelligibility. Objective measures in the technical literature such as spectral distortion and segmental signal-to-noise ratio 2 are not appropriated for the task of evaluating intelligibility in scrambled speech this is so because the objective is not .