Security Analysis of The Speech Scrambling Method Based on Imitation of A Super-Gaussian Signal

A scheme of speech scrambling based on imitation of a super Gaussian signal has recently been proposed. This scheme gives scrambled signals with zero trace of the original content and high scrambling degree. In this paper, the scheme is used in two scenarios: scrambling with private key method (symmetric cryptography), and scrambling with one private and one public key method (a hybrid between symmetric and asymmetric cryptography). Each scenario is analyzed in terms of security to determine if an intruder can reveal the secret content. In the first scenario three kinds of attacks are taken into account: known plaintext, brute force, and known ciphertext. In the second scenario only the brute force attack is considered, because only one information type is transmitted between Alice and Bob. According to theoretical analysis and experimental tests, it has been concluded that the scheme based on imitation of a Super Gaussian signal is highly secure, and that the original content cannot be revealed by a non-authorized user.