Multimedia Tools and Applications

, Volume 75, Issue 14, pp 8403–8418 | Cite as

Audio encryption based on the cosine number transform



In this paper, we introduce an audio encryption scheme based on the cosine number transform (CNT). The transform, which is defined over a finite field, is recursively applied to blocks of samples of a noncompressed digital audio signal. The blocks are selected using a simple overlapping rule, which provides diffusion of the ciphered data to all processed blocks. A secret-key is used to specify the number of times the transform is applied to each one of such blocks. Computer experiments are carried out and security aspects of the proposed scheme are discussed. Our analysis indicates that the method meets the main security requirements of secret-key cryptography. More specifically, after the encryption of 16-bit audio signals, correlation coefficients significantly close to 0 and entropy values close to 16 were obtained. Furthermore, the flexibility of the method easily allows key space sizes greater than 2256 and provides robustness against differential, known-plaintext and chosen-plaintext attacks.


Multimedia security Audio encryption Number-theoretic transform Cosine number transform 



This research was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) under Grants 307686/2014-0 and 456744/2014-2.


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.Department of Electronics and SystemsFederal University of PernambucoRecifeBrazil

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