A Chaotic Searchable Image Encryption Scheme Integrating with Block Truncation Coding

In order to provide secure retrieval for encrypted digital images in cloud-based system, a secure searchable image encryption algorithm based on Block Truncation Coding (BTC) and Henon chaotic map is presented. Henon Chaotic map is used to encrypt two quantization levels of BTC compressed images, and a pseudo random sequence is created by chaotic map to scramble the bit plane of each sub-block. The feature value of each sub-block is computed according to the relationship between the number of 1s and 0s in the corresponding bit plane. The encrypted image retrieval can be achieved by comparing the normalized correlation coefficients between the feature vectors. Experimental results show that the proposed scheme has satisfactory retrieval accuracy and security. Meanwhile, it has low computational cost and can be used for encrypted images retrieval in the cloud.