Cryptanalysis of an image encryption scheme

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.