# A Novel and Robust Hybrid Blockchain and Steganography Scheme
## 3 Methodology and Proposed Method
### Steganography: An Overview
Security means that hidden data cannot be obtained if the stego-multimedia is detected using steganalysis methods. There are methods in which various encryption algorithms are used to provide security, such as encryption of stego-data or encryption of stego-multimedia. In addition, the provision of a secured communication channel is essential to protect against steganalysis methods and increase security. Payload capacity refers to the maximum data that can be hidden in cover multimedia without affecting imperceptibility and security. Successful steganography aims to use the minimum amount of cover multimedia while obtaining the maximum payload. Embedding rate is the ratio of used secret data used in cover multimedia obtained at a high rate. Robustness means that the data hidden using any steganography technique can be obtained from stego-multimedia without any loss after compression, scaling, resizing, rotation, and similar effects [35; 36]. The mediums in which steganography techniques are applied is important in digital steganography [37]. Steganography techniques are applied in mediums such as text, image, network, audio, and video. In addition to these mediums, blockchain should be added to the literature. In blockchain steganography, a new hiding method emerges as a steganography technique. It should be noted that blockchain steganography is different from network steganography. As seen in the literature review section, blockchain steganography studies are based on applying conventional methods differently and assuming novel methods. For this reason, the blockchain medium in digital steganography is an innovation that should be considered as a separate topic. The purpose of steganalysis methods is to detect steganographic communication using various technological possibilities. Although steganography is an old subject of study, studies on steganalysis methods started at the end of the 20 th century due to the opportunities provided by modern technology. Steganalysis methods developed for the detection of widely used steganography techniques offer successful results. Such steganalysis methods are called targeted methods. A general definition of steganalysis methods makes determinations through statistical analysis (such as the pairs of values method) [38]. The artificial intelligence-assisted steganalysis [20] method has been used successfully due to the availability of advanced computer hardware and advances in deep learning techniques. As can be seen, there is a high demand for stronger methods against steganalysis to maintain security and confidentiality at a high level. Because, as with any steganography technique performed on cover multimedia, data hiding will be at risk and become detectable at some stage. The most basic condition to be met is that cover multimedia is not available publicly online. It should not leave an accessible trace by using new steganography methods developed over private platforms. For this reason, blockchain technology offers an excellent opportunity to provide the private platform needed.