In this work, we study on a data encryption scheme based on a shape-variable truncated Baker transformation. First we show statistical properties of the shape-variable truncated Baker transformation. Then we propose a data encryption scheme with this map and verify its performance whether it satisfies fundamental conditions on confusion and diffusion required for data encryption schemes.

This paper proposes a novel chaotic multiple-bits modulation scheme that uses the parameters in the map as data carrier for chaotic digital communication. Chaotic signals modulated with the parameters corresponding to the information to be transmitted are sent to the receiver. The information sent to the receiver can be decoded by a correlation detector. This scheme can increase the number of transmittable information bit per unit carrier signals by increasing the number of mapping parameters to be used for modulation. We verify the performance of this scheme using bit error rate (BER) through computer simulation. Also, we compare the performance of the proposed method with a conventional single-bit modulation scheme.

Some signal design methods for the approximately synchronized CDMA systems based on complete complementary codes have been proposed. It has been shown that estimating the multipath channels and applying the convolution of the spread signals can increase both the information transmission rate and frequency usage efficiency. There are some variations of such signal design methods using complete complementary codes. The efficiency of the communication systems and information transmission rate depend upon the applied signal design method and the modulation scheme. In this paper, we consider two of these signal design methods. We analyze the bit error rate (BER) performances for both methods through some numerical simulations under the single cell scenario. Numerical results show the BER properties under some modulation schemes such as BPSK, QPSK and 16QAM. Some discussions on the relation between the BER performance and the information transmission rate are also included.

In this paper, we focus on an image encryption scheme based on a truncated Baker transformation. The truncated Baker transformation globally preserves the original dynamics of Baker transformation but incorporates a random local rotation operator between two neighbor elements in the mapping domain in order to keep a finite precision. It generates binary sequences (the dynamics of elements) which have statistically good features on ergodicity, mixing and chaotic properties. The image encryption scheme extended from the truncated Baker transformation efficiently shuffles the input gray level image satisfying fundamental conditions on confusion and diffusion required for image encryption schemes. However, this scheme uses many binary sequences and thus needs to keep a large volume of secret keys. In order to solve this problem we introduce Peano space-filling curve in this scheme, which remarkably reduce the key size and mapping iterations without deteriorating good shuffling properties attained by this scheme.