# Empirical Evaluation of Privacy Efficiency in Blockchain Networks: Review and Open Challenges
## 4 Comparative Literary Deductions of Surveyed Privacy Preserving Techniques
### Results of Literary Deductions
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Study** & **Experimental Infrastructure** & **Evaluation Criteria/Parameters** & **Fundamental/Applied** \\ \hline \multirow{4}{*}{[25]} & Programming Language: Solidity & \multirow{4}{*}{Gas Cost} & \multirow{4}{*}{Fundamental} \\  & Test net: Rinkeby (Ethereum), Geth & & \\  & Processor: Intel Core i7 & & Time Overhead & \\  & Clock: 2.7 GHz & & \\  & RAM: 16 GB & & \\ \hline \multirow{4}{*}{[76]} & Multiple machines used for experiments. & Key Generation Time & \multirow{4}{*}{Fundamental} \\  & Machine 1: & Key Size & \\  & Processor: Intel Core i7-2620M Clock: 2.70 GHz & & \\  & RAM: 12 GB & & \\  & Machine 2: & Transaction Latency & \\  & Processor: Intel Core i7-477O Clock: 3.40 GHz & & \\  & RAM: 16 GB & & \\ \hline \multirow{4}{*}{[109]} & System Software: Ubuntu 16.04 & \multirow{4}{*}{Fundamental} \\  & Processor: Intel Core i5-6200U & & \\  & Clock: 2.3 GHz & & \\  & RAM: 8 GB We used the Programming: & & \\  & BouncyCastle’s Java library for Curve 25519 & & \\ \hline \multirow{4}{*}{[23]} & Key Generation Time & \multirow{4}{*}{Fundamental} \\  & & Proving Time & \\  & Amazon EC2 r3.8 xlarge Virtual Machine & & \\  & RAM: 27 GB & & \\  & & & \\  & & & \\  & & & \\  & & & \\ \hline \multirow{4}{*}{[110]} & Operating System: Ubuntu 18.04 & \multirow{4}{*}{Fundamental} \\  & Processor: Intel Core i7 & & \\  & Clock: 2.9 GHz & & \\  & RAM: 8 GB & & \\  & Testnet: Hyperledger Caliper & & \\  & Multiple Phase Experiments & & \\  & Experimental Rounds/Phase: 30 & & \\ \hline \multirow{4}{*}{[82]} & Contracts Programming: Solidity & \multirow{4}{*}{Gas Cost} & \multirow{4}{*}{Fundamental} \\  & Off-chain Signature Programming: JavaScript & & \\ \cline{1-1}  & Testnet: Kovan, Ethereum & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: _Cont._Novel Framework for Empirical Evaluation of Privacy Efficiency in Blockchains Based on Identified Parameters  
Since current evaluation parameters for blockchain based privacy solutions are insufficient, hence we further surveyed the literature to find more parameters for validation. From the survey, we found a number of essential characteristics that a blockchain based solution shall possess. Moreover, we also found out the parameters and criteria to evaluate those characteristics or features. Further, we also formulate a validation framework that will efficiently verify the ability of a proposed blockchain privacy solution. This work is loosely based on [7]. However, the problem with the study is that the study is focused on a limited type of privacy preserving solutions i.e., related to Internet of Things (IoT) networks. Moreover, the solution presented in the study [7] considers various parameters based on their presence or absence, it does not account for the degree of usefulness and efficiency of each parameter which is highly essential. Therefore, we enhanced the solution by first removing any parameters specific to IoT applications, to facilitate diverse applications. Next, we introduce some new parameters that have greater or at least equivalent significance in terms of privacy protection (details are mentioned later in this section). Moreover, we also introduce some performance evaluators to evaluate the efficiency of given parameters to assist in determining how effective a parameter is in preserving the privacy of the given technique. Since this work is loosely based on [7], hence, the weights taken for each of the characteristic are same as in the study. We discuss those parameters, performance evaluators, and the corresponding framework in detail in this section. To evaluate the solution, we will calculate privacy precision of each solution. To do so, we divided the surveyed factors in two categories, i.e., privacy attributes and privacy risks. Privacy attributes consist of the factors that strengthen the privacy if present in a solution whereas privacy risks correspond to weaknesses of a solution, i.e., the risks that the solution is vulnerable to.