# Utilizing Blockchain for IoT Privacy through Enhanced ECIES with Secure Hash Function
## 3 Modified ECIES with Secure Hash Function
### Computation Time for Proposed Scheme

In this section, we calculate the computation time of the proposed scheme, which is given as:

\[T=T_{b}+T_{c},\]

where \(T\) is the final computation time, \(T_{b}\) is a computation time for transaction generation and verification, and \(T_{c}\) is the initial computation time. Here, \(T_{b}\) is given as:

\[T_{b}=\sum_{i=1}^{T_{r}}T_{r}^{i}(t)+\sum_{i=1}^{\frac{N_{b}}{2}+1}N_{s}^{i}(t),\]

where \(T_{r}^{i}(t)\) is a time for generation of one trade, and \(N_{s}^{i}(t)\) is a time for verification by session node. Moreover, \(T_{c}\) is given by:

\[h(m)=\psi(m)\quad|\quad\psi:\{0,1\}^{*}\rightarrow\{0,1\}^{256},\]0

where \(T_{h}\) is the time for generation of hash function, and \(T_{1}\) and \(T_{2}\) correspond to the time of public/private key calculation and public parameter generation. ## 4 Benefits of Modified ECIES with SHF

The proposed solution helps improve the confidentiality and authenticity of the transferred message to obtain consents protected by using an SHF to generate private and public keys. This improves the correlation coefficient between transmitted messages and encrypted transactions. Along with this, it also ensures that the attacker is not able to detect the value of the key even in case hash function is known to the attacker because points on the elliptic curve are the order of a large prime number. In some of previous woks, the computation time is affected by the number of users, thus with the increase in the number of users, the computation time also increases, indicating the unreliability of the system. In the proposed scheme, the computation time is calculated by eliminating the user dependent variable, showing a higher system reliability. SHF is utilized to generate private and public keys for improving the security strength of the transmitted message. The private key is generated from the SHF based on SHA-256, while the public key is calculated from the private key and points on the elliptic curve of the finite field that is the order of a large prime number. Hence, if the attacker tries to compute the point on the curve, they will not be able to detect the value of the key. In order to improve the efficiency of the encryption and decryption, the KDF is used to generate secured multiple keys from one master key. Some previous works [14] randomly select the publicly exposed point on the curve as a value of the key resulting in several security vulnerabilities that impact user privacy. Using publicly exposed points on the curve that are vulnerable to several attacks as a private and public key, will exploit the user privacy in IoT. Hence, the use of SHF will guarantee that the integrity of the key is protected, and the attacker is not able to detect the actual value of the key. In the proposed scheme, we have kept a regard for the authenticity and integrity protection of the transmitted message while consent management for enhancing user privacy in IoT by using ECIES with an SHF generation. ## 5 Results and Discussion

This section presents the analysis and results of the proposed scheme. Considering the relevance of [PERSON] et al. [14] to our work, we provide a detailed comparison of our work with the results presented in [PERSON] et al. [14]. MATLAB R2019a was used to implement and evaluate the prototype of the proposed model on a personal computer (PC). For the implementation,'secp256r1' is used as the elliptic curve domain parameter [39] to develop the public parameter of the elliptic curve, whereas SHA-256 is used to securethe hash function generation. Four groups of 50, 150, 250, 500 device information were used as a dataset, where these datasets were taken from online resources [40]. Ten samples of device information from each group are taken to construct the request transactions. We considered attributes such as device_ID, device_Type, device_Model, and device_SN (serial number) from the device information for creating the transaction request. The completed request transaction is encrypted and decrypted for both [PERSON] et al.