Securing speech noise reduction in outsourced environment

Cloud data centers (CDCs) are becoming a cost-effective method for processing and storage of multimedia data including images, video, and audio. Since CDCs are physically located in different jurisdictions, and are managed by external parties, data security is a growing concern. Data encryption at CDCs is commonly practiced to improve data security. However, to process the data at CDCs, data must often be decrypted,which raises issues in security. Thus, there is a growing demand for data processing techniques in encrypted domain in such an outsourced environment. In this article, we analyze encrypted domain speech content processing techniques for noise reduction. Noise contaminates speech during transmission or during the acquisition process by recording. As a result, the quality of the speech content is degraded. We apply Shamir's secret sharing as the cryptosystem to encrypt speech data before uploading it to a CDC. We then propose finite impulse response digital filters to reduce white and wind noise in the speech in the encrypted domain. We prove that our proposed schemes meet the security requirements of efficiency, accuracy, and checkability for both semi-honest and malicious adversarial models. Experimental results show that our proposed filtering techniques for speech noise reduction in the encrypted domain produce similar results when compared to plaintext domain processing.