An image encryption scheme with a pseudorandom permutation based on chaotic maps

Many research efforts for image encryption schemes have elaborated for designing nonlinear functions since security of these schemes closely depends on inherent characteristics of non-linear functions. It is commonly believed that a chaotic map can be used as a good candidate of a nonlinear component for image encryption schemes. We propose a new image encryp-tion algorithm using a large pseudorandom permutation which is combinatorially generated from small permutation matrices based on chaotic maps. The random-like nature of chaos is effectively spread into encrypted images by using the permutation matrix. The experimental results show that the proposed encryption scheme provides comparable security with that of the conventional image encryption schemes based on Baker map or Logistic map. With the rapid developments in the multimedia industry and communications, a great deal of concerns have been raised in the security of multimedia data transmitted or stored over open channels. A major challenge is to protect confidentiality for multimedia data in digital distribution networks. The most effective method is to encrypt multimedia data so that the only authorized entities with the key can decrypt them. In practice Advanced Encryption Standard (AES) [1] has been widely recognized as de facto standard in multimedia industry. However, it is known that conventional encryption schemes such as AES have obvious limitations on the multimedia specific requirements [2] as follows: Perceptual quality control: An encryption algorithm can be used to intentionally degrade the quality of perception, but still keep the multimedia data visually perceivable. Codec/format compliant: It could be desired that the encryption algorithm preserves compression format of the multimedia data, so that the standard decoders can still decode the encrypted data without crashing. Real-time constraint: In many multimedia applications, it is important that the encryption and decryption algorithms are very efficient to access multimedia data in real time similar to unprotected data. As one of speed up techniques, some important parts of multimedia data can be selectively encrypted. To meet these challenges, many multimedia encryption schemes have been proposed [2,3]. A common design principle is to use nonlinear functions as fundamental building blocks for encryption [4]. Nonlinear components are essential to every strong cryptographic primitive. In conventional block cipher algorithms such as AES nonlinear functions are generally implemented as S-box which is a table-driven nonlinear substitution operation [1].