Low Color-Depth Image Encryption Scheme for use in COTS Smartphones

Cyber security and privacy are sources of increasing importance for the successful deployment of information and communication technology. This paper investigates aspects concerning privacy during the communication of low color depth images in encrypted form via low bit-rate, error prone channels. Existing approaches for region of interest determination in images, image encryption and image compression within this context are presented. The problem is established and conflicts between the aims of data compression and data encryption are out-lined and theoretically founded. An innovative approach is hence presented that automatically selects regions of interest in low color depth images, while achieving an acceptable level of security without increasing the data volume of the resulting image. The technique is suitable for cases where the data being transmitted has a limited lifecycle period and the compressed and encrypted image data are likely to be corrupted, such as the transmission via channels that are not guaranteed error – free. An error correction add-on to the algorithm permits an increase on the average decrypted image quality. Initial cryptanalytic resilience results for the proposed scheme are given. The proposed scheme is intended as a means of facilitating the deployment of COTS technology in tactical situations, by increasing the level of security of the underlying infrastructure. Key-Words: image encryption; encoding; low resolution; error resilience; COTS