Privacy Protected Surveillance Using Secure Visual Object Coding

This paper presents the Secure Shape and Texture SPIHT (SecST-SPIHT) scheme for secure coding of arbitrarily shaped visual objects. The scheme can be employed in a privacy protected surveillance system, whereby visual objects are encrypted so that the content is only available to authorized personnel with the correct decryption key. The secure visual object coder employs shape and texture set partitioning in hierarchical trees (ST-SPIHT) along with a novel selective encryption scheme for efficient, secure storage and transmission of visual object shape and textures. The encryption is performed in the compressed domain and does not affect the rate-distortion performance of the coder. A separate parameter for each encrypted object controls the strength of the encryption versus required processing overhead. Security analyses are provided, demonstrating the confidentiality of both the encrypted and unencrypted portions of the secured output bit-stream, effectively securing the entire object shape and texture content. Experimental results showed that no object details are revealed to attackers who do not possess the correct decryption key. Using typical parameter values and output bit-rates, the SecST-SPIHT coder is shown to require encryption on less than 5% of the output bit-stream, a significant reduction in computational overhead compared to “whole content” encryption schemes.