A joint image lossless compression and encryption method based on chaotic map

Nowadays poor security, low transmission and storage efficiency of images have become serious concerns. In order to improve the situation, this paper put forward a new image lossless compression joint encryption algorithm based on chaotic map with all original information intact. The lossless compression uses SPIHT(Set Partitioning in Hierarchical Trees) encoding method based on integer wavelet transform, and encrypt multiple rounds in the process of wavelet coefficients and SPIHT coding applying many kinds of chaotic maps. Experimental results show that the compressed file size is about 50 % of the original file size, which achieves relatively good lossless compression ratio. Besides, the encryption method passes many security tests, such as sensitivity test, entropy test, autocorrelation test, NIST SP800–22 test. There is a high application value in the medical field and the national security department whose image files require a relatively high quality.