Abstract
Recently, many scholars have proposed chaotic cryptosystems in order to promote communication security However, there are a number of major problems detected in some of those schemes such as weakness against differential attack, slow performance speed, and unacceptable data expansion In this paper. we introduce a new chaotic block cipher scheme for image cryptosystems that encrypts block of bits rather than block of pixels It encrypts 256-bits of plain image to 256-bits of cipher image within eight 32-bit registers The scheme employs the cryptographic primitive operations and a non-linear transformation function within encryption operation, and adopts round keys for encryption using a chaotic system The new scheme is able to encrypt large size of images with superior performance speed than other schemes The security analysis of the new scheme confirms a high security level and fairly uniform distribution (C) 2009 Elsevier B V All rights reserved