# A Novel and Robust Hybrid Blockchain and Steganography Scheme
## 1 Introduction  
Steganography [1] is a working principle that emerges from the moment it is realized that information is valuable and needs to be hidden. At its core lies the concealment of information inconspicuously [2]. There are known examples of steganography that have been carried out by many methods throughout history [3]. For example, steganography methods have been known, such as tattooing the information to be hidden onto a slave's scalp after their hair has been cut, sending the message to the person to whom the message will be delivered after the slave's hair grows back, or transmitting the information using wax tablets [4].  
With the advancement of technology and the emergence of new opportunities, steganography studies are also developing in this direction [5]. Likewise, with a better understanding of the possibilities of using blockchain technology, it is seen that steganography can be used together with blockchain [6; 7; 8]. Blockchain technology has emerged as a suitable subject for steganography studies with its distributed architecture, anonymity, and data security [9; 10].  
Blockchain technology is a joint study of computer science and cryptology [11]. Blockchain systems have a decentralized structure [12; 13]. Each of the nodes that make up the system has an up-to-date version of the blockchain data. For this reason, data are distributed systemically to resist attacks [14]. Hash functions link the blocks that makeup the blockchain system [15; 16]. Because these functions work unilaterally and give different values in case of any tampering, they keep the system security at the highest level [17]. Since the introduction of Bitcoin in 2009 by [PERSON], the importance of blockchain technology has been better appreciated, and studies have been carried out on its application areas. Blockchain technology can be added to existing systems as a layer, or it is possible to find examples developed using only blockchain. Blockchain systems can be developed using Bitcoin, Ethereum, and Hyperledger, and many similar platforms [18]. In addition, without using these platforms, blockchain systems can be developed using programming languages such as JavaScript, Solidity, and Java [19]. Under special circumstances, systems are designed where it is possible to add your own desired features. Due to such possibilities, blockchain technology is a study subject used in many areas, such as finance, transportation, public services, identification, and authentication.  
In the literature review of this study, it can be seen that traditional methods of digital steganography are utilized to achieve similar results obtained in the blockchain technology. Considering the profound effect of Bitcoin crypto money on the financial sector, blockchain technology should introduce new methods into steganography. For this reason, it is necessary to fully understand the capabilities of blockchain technology and to identify innovative methods to meet steganographic needs.  
Various methods are used to measure the success of steganography methods and to detect stego-data as it is not realistic for humans to detect and analyze the steganography methods used today. For this reason, many computerized steganalysis methods are used to detect steganography-applied multimedia stego-data [20].  
The essence of steganography is the concealment of information, and it is not necessary to do this hiding process with conventional methods [21]. Hence, this study proposes the Ozyavas-Takaoglu-Ajlouni, OTA blockchain steganography algorithm. The proposed method uses hybrid steganography with blockchain technology. With the OTA algorithm, all steganalysis methods used today will be invalidated. The OTA algorithm does not cause any distortion to the cover image, and it performs the information hiding process with an algorithm developed iteratively. This study has a literature review, materials and methodology, analysis, results, and discussions sections.