Shujun Li The Hong Kong Polytechnic Univ. (China) Chengqing Li City Univ. of Hong Kong (Hong Kong China) Kwok-Tung Lo The Hong Kong Polytechnic Univ. (Hong Kong China) Guanrong Chen Hong Kong Polytechnic Univ. (China)
We present cryptanalysis of an image encryption scheme, which is based on the base-switching (BS) lossless compression algorithm. The following conclusions are reached: 1. the size of the key space, i.e., the security against brute-force attacks, was greatly overestimated by the designers; and 2. the scheme is not secure against known/chosen-plaintext/ciphertext attacks. A real example is given to show the feasibility of a proposed chosen-plaintext attack. In addition, some other minor problems of the joint compression-encryption scheme are also pointed out.