# Secure Video Communication Using Multi-Equation Multi-Key Hybrid Cryptography
## 3 Proposed Method
### Proposed Algorithms
The attributes related to user registration are identified and shared between the media server and the user. This is used in the encryption process. Hence, each user will have a different set of equations for the processing. The determined equation set is put to use to produce the key for the encryption process. As a result, each chunk is assigned a unique key that is produced by a distinctive equation. The complexity of the suggested algorithm will increase as a result of this. As demonstrated in Algorithm 1, the equation is utilised in conjunction with the key generated earlier for the preceding chunk. The algorithm makes use of many different user attributes, such as the MAC address, user name, contact information, and so on, in order to make it more difficult to use. Following the generation of a unique key for each video chunk, the Advanced Encryption Standard (AES) algorithm is used to encrypt the video chunks. Within the context of this multi-key and hybrid method, the suggested method does not share any of the keys. The key for video communication is generated on the run, as detailed in the algorithm; as a result, the highest possible level of security can be attained. The fact that brute-force attacks can only compromise one chuck at a time does not compromise the security of the remaining video data. This is one of the most important aspects of the suggested method. Similarly, the algorithm shown in Algorithm 2 demonstrates the steps involved in the decryption process. In our proposed method, the process of decryption remains the same as the encryption steps. ```
1:Input encrypted \(Vc_{0}\)
2:Read receiver's public key of the \(R_{Pkey}\)
3:Read receiver's attributes \(U_{attr}\)
4:Decrypt first encrypted chunk \(Vc_{0}\) using \(RSA\)
5:Generate \(V_{ID}\) using first chunk \(Vc_{0}\)
6:Store \(V_{ID}\) in a temporary file
7:Read index value \(j\) from the agreement base
8:Generate \(Key_{a}\gets EQ_{j}\{V_{ID},U_{attr}\}\)
9:Decrypt \(Vc_{1}\) using \(Key_{a}\) and \(AES\)
10:for i:=2 to ndo
11:Generate \(Key_{a}\gets EQ_{j}\{Key_{a},U_{attr}\}\)
12:Decrypt \(Vc_{i}\) using \(Key_{a}\) and \(AES\). 13:endfor
```  
**Algorithm 2** Decryption flow  
Case Study:  
The key is created for each chunk as follows:  
Initially, the video ID is generated and used for generating the subsequent keys. To generate \(V_{ID}\), the process uses a public key \(R_{Pkey}\) and a user attribute \(U_{attr}\). Later, the equation set is used for key generation. Assume the following equation has been used to generate the key for the first video chunk \(Vc_{1}\). \[y=ax^{2}+bx+c \tag{1}\]  
The proposed method considers \(V_{ID}\) as \(a\) and \(U_{attr}\) as \(b\) in Equation (Equation (1)). In the proposed method, a value for \(c\) will be generated at the time of user registration. The same value of \(c\) will be used throughout the process. Hence, the modified equation is as follows:  
\[Key_{a}=V_{ID}\times x^{2}+U_{attr}\times x+c \tag{2}\]The first video chunk uses Equation (2) to generate the key. The second chunk will obtain a different equation, which is assumed here as Equation (3). The algorithm considers previously computed \(Key_{a}\) instead of \(V_{ID}\), as shown in Equation (4). This process continues for all the remaining chucks in the video. \[y=\frac{-ax-c}{b} \tag{3}\]  
\[key_{a}=\frac{-Key_{a}\times x-c}{U_{attr}} \tag{4}\]  
The key \(key_{a}\) is generated using Equations (2) and (4) specified in the encryption and decryption method. Given the consideration of the 128-bit key size for the Advanced Encryption Standard (AES), it is necessary to pad additional bits to the variable \(key_{a}\) in order to achieve the desired size. Multi-equation multi-key hybrid cryptography is a versatile approach that combines symmetric and asymmetric encryption to provide a robust security framework for data protection. It offers a potent solution for safeguarding data confidentiality by using asymmetric encryption to securely exchange a symmetric key, which is then employed for efficient bulk data encryption.