<title>Truncated Baker transformation and its extension to image encryption</title>

This paper presents a new truncated Baker transformation with a finite precision and extends it to an efficient image encryption scheme. The truncated Baker transformation uses the quantization error as a secret key, which is always produced by contraction mechanism in the mapping process. The original dynamics by Baker transformation is globally preserved but a random level rotation operator is incorporated between two neighbor elements in the mapping domain in order to keep the same precision. Such perturbations are local and small in each mapping, however, as the mapping process goes on they will gradually accumulate and affect the whole dynamics. Consequently, generated binary sequences (the dynamics of elements) have statistically good features on ergodicity, mixing and chaotic properties. The extended image encryption scheme efficiently shuffle the input gray level image making difficult for a third party to decode the ciphered data to the original image without knowing the proper secret key.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.