Novel methods for data hiding on multimedia data

As internet became the most popular communication platform and more and more devices with internet connection are used in everyday life, more personal information started to digitize. The widespread use of the internet has led to the development of information technology. As information technology develops, the importance of information security increases as well. Cryptology and data hiding are the most commonly used methods to provide information security. While encryption change the content of the message, data hiding embeds the message. Cryptographic methods are mostly used to provide information security in modern computer and network technologies. However encrypted messages get the attention of the attackers and thus they are subjected to many attacks. Data hiding is used to solve this problem by embedding the secret message to a cover object. While data hiding provides a secure transmission channel, it can also be used for copyright and authentication purposes. In this thesis, new methods are developed to solve problems in data hiding methods. There are nine methods in four main topics which are secret sharing based data hiding methods, visual cryptography based multimedia data hiding and image authentication methods, multilayer data hiding methods and block based data hiding methods. • A new DNA-XOR based secret sharing algorithm is created by building-up on a XOR secret sharing algorithm. This algorithm was used in data hiding and obtained successful results. In this methods, capacities are 1.5 and 2 bpps. Peak Signal-to-Noise Ratio (PSNR) is obtained as higher than 51 dB by selecting values that distort cover object at the very least. • Visual cryptography algorithms produce noise-like secret components in general and these algorithms are exposed to attacks. In order to secure the secret shares against attacks and forgery, new meaningful visual secret sharing schemas are created. These secret share are hidden with data hiding algorithms. Expansion coefficient and the cost of these algorithms was obtained less than other visual cryptography methods. • In order to increase data hiding capacity, multi-level data hiding algorithms are suggested. High payload capacity and visual quality was obtained by using these methods. • Block based data hiding algorithms are examined. Two different data hiding algorithms based on direction vector and Minesweeper game are suggested and it is pointed out that data hiding can have a multi-disciplined field. New data hiding schemes which has secure, high payload capacity and high visual quality were created by using these methods.