Decryption of BSS based encrypted speech without a priori knowledge of the key signal

When speech is transmitted over non reliable channel, encryption techniques are needed to secure the communication. BSS-based speech encryption aims to encrypt speech signal by linearly combining it with secret key signal. Decryption can be done only if the receiver has the secret confidential key. In this paper, we study the possibility of recovering an intelligible version of confidential signal from encrypted one. The proposed method shows that it is feasible to extract an intelligible version of speech even without the secret key.