A novel NMF-based authentication scheme for encrypted speech in cloud computing

Authentication of encrypted speeches is a technique that can judge the integrity of encrypted speech in cloud computing, even the encrypted speeches have been subjected to common signal processing operations. In this paper, a novel and effective authentication scheme for encrypted speech is proposed. At first, the host speech signal is first scrambled and encrypted by Advanced Encryption Standard (AES). Then, Integer Wavelet Transform (IWT) is performed to obtain the approximation coefficients and the detail coefficients. At last, Non-negative Matrix Factorization (NMF) is employed to generate perceptual hashing, which is embedded into the encrypted speech by differential expansion. In authentication section, the tampered region of encrypted speech is located by comparing the reconstructed perceptual hashing with the extracted perceptual hashing version. Extensive experiments are carried out, which demonstrate that the proposed scheme is not only sensitive to malicious tampering of encrypted speech files, but also robust to tolerate common signal processing operations. The comparison shows that our algorithm performs better than the existing methods on Bit Error Rate (BER) values.