# A Novel and Robust Hybrid Blockchain and Steganography Scheme
## 3 Methodology and Proposed Method
### Proposed Ozyavas-Takaoglu-Ajlouni (OTA) Algorithm
#### 3.3.1 OTA-Steganography Algorithm
Secret data of any size can be hidden using a single cover multimedia without causing any deterioration on the cover multimedia. In the study proposed by [PERSON] et al. [23], COVID19 data, including high-resolution images, are transmitted over the blockchain system. Unlike this system, where the blockchain system is burdened with storing high volumes of data, the OTA algorithm transmits only an encrypted address array using only 1 KB data, with only indictors of the actual data, not the actual data itself. [PERSON] and [PERSON] [24], on the other hand, used the LSB method within their proposed Ethereum platform and introduced it as transaction steganography. Although the study is designed much more robustly than its counterparts, it remains weak at hiding capacity due to the use of the traditional steganography technique. In addition, because the Ethereum system is used, each transaction costs more as the value of Ether increases. The OTA algorithm is superior in terms of hiding capacity and cost. [PERSON]'s [25] theoretically proposed work can send 1 byte of stego-data requiring more than one hour to accomplish its task. In terms of speed, the OTA algorithm performs better. Although the RDHEI algorithm proposed by [PERSON] et al. [26] is difficult to implement in real life, it offers 0.8 bpp embedding rate success. In the OTA algorithm, the embedding rate is 100%. [PERSON] et al. [27] aimed to transmit steganographic information using the existing public blockchains. However, the hardware requirements to be a miner in public blockchains such as Bitcoin and Ethereum and the information that can be inserted in a block specified in the genesis block are limitations in such a system. In this context, the OTA algorithm overcomes the public blockchain handicap faced by [PERSON] et al. [27] and offers a platform where stego-data can be recorded without any problems because of its initial design. [PERSON] et al. [29], on the other hand, proposed a staganalysis method to detect blockchain steganography. As stated in their studies, there is no steganographic communication they can detect. Because of the private blockchain used by the OTA algorithm, the steganalysis methods they suggested do not work because they cannot access it. The blockchain leg of the algorithm ensures that the system is decentralized, anonymous, and tamper-proof. In addition, because the author developed all the coding required by the OTA algorithm, the algorithm's future improvement can easily be implemented, resulting in zero system cost. Because the OTA algorithm is proposed to address a specific need, it is likely that blockchain will not receive the high attention that many finance applications have. This has a positive effect on the system's scalability issue because the consensus algorithm works without difficulty. In addition, the weaknesses to be encountered during the completion of the front-end studies of the system and the public trial of the system will be carefully examined, and the improvement processes will be carried out continuously. The proposed system moves away from traditional steganography. It does not embed the secret data in the cover multimedia, thus causing no degradation in the cover multimedia, but uses blockchain blocks as its medium to store the secret data. It also utilizes the proposed private OTA blockchain as an additional layer of security while storing the encrypted address array as transactions. The OTP encryption applied to the address array that contains the indices from the cover multimedia encoding the secret message aims to prevent insider attacks. Private blockchain system integration also ensures that the proposed system is decentralized, anonymous, and tamper-proof. In addition, any weaknesses encountered during the implementation of the front-end of the system and the public trial will be carefully examined, and any required improvement processes will be carried out continuously. ## 5 Conclusions

The OTA algorithm is proposed as a novel method for blockchain steganography.