# 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
The method of recovering the secret data hidden by the OTA-steganography algorithm is presented in Algorithm 2, where A represents the multimedia obtained from the URL, K is the key, and Ci is the information of how many bits the plaintext is divided into, that is, pieces. CSD refers to the encrypted steganographic information received from the OTA-chain. The cover multimedia obtained from the server is used together with the marking addresses obtained by applying a reverse OTP algorithm using the key and CSD data. The addresses in the C array are read one by one, found in the A cover multimedia, and written into the B array. When the algorithm completes its work, the secret data hidden by the OTA-steganography algorithm is fully recovered. Because the OTA-steganography algorithm uses the cover multimedia bits' addresses to represent the bits of the secret data, it does not cause any deterioration to the multimedia file. Thus, all steganalysis techniques used today become useless. Keeping the used cover multimedia on a private server is of great importance for the OTA-steganography algorithm because, theoretically, any corruption in the public channel and on the cover multimedia will cause some changes in the plain text. For this reason, it has been decided that using a server for cover multimedia in the OTA-steganography algorithm is a safer method. In addition, testing shows the use of public channels detected no change in the cover multimedia. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **128 Byte** & **256 Byte** & **512 Byte** & **1 kB** & **4 kB** \\ \hline
4-bit pattern & \(\sim\)100\% & \(\sim\)100\% & \(\sim\)100\% & \(\sim\)100\% & \(\sim\)100\% \\ \hline
6-bit pattern & 99.99\% & \(\sim\)100\% & \(\sim\)100\% & \(\sim\)100\% & \(\sim\)100\% \\ \hline
8-bit pattern & 98.34\% & 99.97\% & 99.99\% & \(\sim\)100\% & \(\sim\)100\% \\ \hline
10-bit pattern & 63.30\% & 86.62\% & 98.22\% & 99.96\% & \(\sim\)100\% \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Probability of finding n-bit pattern in an m-bit cover multimedia. ```
1:letA = {A1,A2,A3,...,An}
2:letB = {B1,B2,B3,...,Bn}
3:upload the cover multimedia to the server and get URL //for2 bits marking
4:letCb = { Cb1,Cb2,Cb3,...,Cbnn } then
5:Cb = Cb1 then
6:ifB \(\
eq\) {} then
7:forA andB do
8:ifAn == Bn do
9:addAn.location toCb then
10:eraseBn fromB
11:ifCb1-.tenght >= 1024 then
12:letCb = Cbnn+1
13:endif
14:endif
15:endfor
16:endif
17://for3 bits marking
18:letCb1 = { Cb1,Cb2,Cb3,...,Cbnn } then
19:letCb = Cb1b1 then
20:forA andB do
21:ifAn == Bn do
22:addAn.location toCbthen
23:eraseBn fromB
24:ifChb.tenght >= 1024 then
25:letChb = Cbnb1 then
26:endif
27:endif
28:endfor
29:endif
30:iffor4 bits marking
310:letCb = Cb1,Cb2,Cb3,...,Cbnn then
32:\(\text{C}_{\text{fb}}=\text{C}_{\text{fb1}}\)then
33:ifB \(\
eq\) {} then
34:forA andB do
35:ifAn == Bn do
36:addAn.location toCb then
37:ifCb1-.tenght >= 1024 then
38:letCb = Cb1+1
39:endif
40:endif
41:endfor
42:endif
43:letC = {}
44:selectmin.length (Cb,Cb,Cb),Cb) ==>C then
45:letCi = selected (Cb,Cb,Cb,Cb),Cb) information //Marking part will continue to the desired bits number. In our study it's 10 //One Time Pad process
46:letK
47:letCSD
48:generateK size ofC.length then
49:CSD = K \(\oplus\) C
50:returnCSD,K,C\({}_{i}\),URL

#### 3.3.2 OTA-Chain Algorithm

The OTA-chain algorithm has been specially developed to meet steganographic needs. Nodes in the OTA-chain system containing steganographic information can securely communicate with each other. Platforms such as Bitcoin, Ethereum blockchain, or the Hyperledger platform have not been used. The reason for this is to keep the system costs lower, as stated in the previous sections. Because the OTA-chain system works using OTA coin, an OTA coin will be sent to the receiver together with stego-data, and the coin for the receiver's wallet functions as a reminder with a warning message to the user. That is, coin sending works like a ring mechanism that informs the receiver.