Hadamard transform application in speech scrambling

Abstract

Speech scrambling procedures may be considered as typical orthogonal transforms applications. This point of view was rarely applied since all the scramblers were based on the same orthogonal transformsimple permutation of speech components (time segments andlor frequency subbands). This approach is regarded as an insecure speech encryption method and recently a new speech scrambling concept was proposed, based on Hadamard transform of the speech components. Linear combination of the speech components based on Hadamard matrices instead of conventional permutation gives better cryptographic performances, maintaining all the good features of the scrambling concept. In this paper scrambling procedures are investigated from two points of view: the transform matrix features as well as the corresponding transform kernel. This theoretical analysis gives a subtle view to scrambling procedures.

Progressive Audio Scrambling in Compressed Domain

“…Milosevic et al [14] present an algorithm that makes use of Hadamard matrices to perform scrambling. It not only changes the sequence of the data elements, but also the values.…”

Design of integrated multimedia compression and encryption systems

“…These schemes have high residual intelligibility [7], and are relatively easy to crack using modern computers [8]. As digital signal processing became popular, the focus shifted to scrambling in the domain of orthogonal transforms, such as DFT [8,9], DCT [7,10], the wavelet transform [11] and the Hadamard transform [12]. These new transform domain scrambling techniques have much lower residual intelligibility than old ones.…”

Frequency Speech Scrambler Based on the Hartley Transform and the Insertion of Random Frequency Components

“…Francisco Assis de O. Nascimento and Ricardo G. Toscano literature (Dawson, 1991;Milosevic, Delic, and Senk, 1997).…”