Notary Blockchain Applicatio n Development – CA1 202 2 - 21133824 2 Table of Contents 1. Objectives ................................ ................................ ................................ ........................... 3 2. Background ................................ ................................ ................................ ........................ 3 3. Technical Approach ................................ ................................ ................................ ........... 6 3.1 SHA - 256 ................................ ................................ ................................ ................................ 6 3.2 Public and private key ................................ ................................ ................................ ........... 7 4. Special resources required ................................ ................................ ................................ 9 5. Project Plan ................................ ................................ ................................ ....................... 9 6. System Desi gn ................................ ................................ ................................ .................. 12 6.1 Use Case ................................ ................................ ................................ .............................. 14 6.2 Requirements Specification ................................ ................................ ................................ 17 7. Technical Details ................................ ................................ ................................ ............. 19 7.1 Backend ................................ ................................ ................................ ............................... 19 7.2 Frontend ................................ ................................ ................................ .............................. 21 7.3 Hosting ................................ ................................ ................................ ................................ 24 8. Evolution ................................ ................................ ................................ .......................... 25 “Imagine a world in which all people can trust each other.” Nicolas Cary, Co - Founder & Vice Chairman at Blockchain.com Blockchain Applicatio n Development – CA1 202 2 - 21133824 3 1. Objectives The main objective and general goal of this proposal is blockchain technology in the context of potential use in the public notary services sector. The subject of the application is the operation of blockchain tec hnology, which uses very advanced cryptographic, computer and mathematical tools in combination with legal concepts, relate to the possibility of using a decentralized notarial system. I would like to exemplify how blockchain technology can solve the probl em of digital proof of existence and possession, by certifying that digital assets have existed at a specific date and time. A Digital Notary is a web - based service thanks to which anyone can generate a confirmation that intellectual good existed at a cert ain moment and was in its possession. By using the website, users can provide indisputable evidence of the existence of an intellectual good. The evidence is obtained by creating a digital fingerprint in the form of a cryptographic hash , and by adding a tr usted timestamping mechanism, defining the specific moment of the date and time in which it was created. Th e hash constitutes the exact contents of the file uploaded. Service allows for inclusion in the chain of cryptographic blocks information about the file selected by the user. Digital Notary does not receive a file and it is not possible to read its content. The file itself is not available to the public, but the use of cryptography allows one to check with complete certainty whether the file was m odified after placing it on a blockchain. When the same file is uploaded again, the same hash will be created and then verify that the file is the same. Even the slightest change in the input data will cause a complete change in the hash. If the file has c hanged in any way, the new hash will not match the previous one. This way the application verifies the file. Due to the decentralization of the blockchain, it is also not possible to interfere with the information about the file Digital Notary and the mat hematical foundations of this service may be successfully used in the future by the courts to take evidence from the document. I t helps to secure digital files of any size, in any format, regardless of whether they are numerical, images, text or audio - visu al files. This application is to allow users to confirmation of ownership without disclosing the information it contains. It is addressed to all users expecting a fast and functional interface, reliability and convenient service. This service, based on blo ckchain, constitutes a certain equivalent of notarial confirmation of the existence of a traditional document about digital data, except that we are certainly guaranteed by the principles of mathematics. Blockchain allows for the building of trust between people without intermediaries. We do not need offices to issue certificates and third parties to settle disputes. 2. Background Blockchain is a compilation of previously functioning technologies and concepts such as cryptography and game theory in the form of a peer - to - peer exchange network. It is an innovative solution allowing the storage of information in distributed databases, in which participants are entitled to enter, save, share and store any data. An important feature of blockchain is immutability, any information saved in blockchain cannot be modified, and in addition is ranked with the information preceding and following it, which prevents it from interfering. This information is stored in the form of blocks. Each of the blocks can contain a certain amount of data. When the block is filled, another block is created. In this way, a kind of chain arises. The easiest way is t o be characterized as a digital ledger that allows the saving and storing of information on internet transactions. It is a communication model in a computer Blockchain Applicatio n Development – CA1 202 2 - 21133824 4 network that provides the same rights to all network users. The entry introduced to the blockchain will be checked and must be signed cryptographically. Most importantly each block contains encrypted information from the previous block. So the introduction of an additional structure, mismatched to the previous one, would result in the disconnection of a ll subsequent blocks. For this reason, blockchain technology is ground - breaking. Transaction blocks cannot be removed. The whole structure is encrypted, stable and historically unchangeable. Thanks to this, we get a public trust system that is based on blo ckchain technology. A characteristic feature of this technology is decentralization which guarantees the integrity, invariability and transparency of the data saved on it s o the system can function, and no main element of infrastructure is needed. All tran saction data is saved by individual users, without the participation of the central system. All this, in a natural way, becomes a good tool for storing all kinds of registers in which it will not be possible to replace once recorded data. Typical examples may be land and mortgage registers, acts, contracts, wills, intellectual property, etc. Figure 1 Trust via Notary, https://www.dreamstime.com/imprimir - image212196285 You may have already bought a house or concluded another purchase and sale agreement. If so, you know that a visit to a notary is needed for this type of transaction. What does a notary public do? He will confirm that a given contract was concluded, for ex ample, between Mr Smith and Mrs Doubtfire, on July 3, 2022, and the subject was the purchase/sale of real estate at Sesame Street in New York City. In such a situation, the notary plays the function of the third, impartial intermediary. However, I believe that it could be replaced with blockchain Blockchain Applicatio n Development – CA1 202 2 - 21133824 5 technology . In place of the trusted third intermediary, we simply introduce an element of the trusted ledger. More importantly, this ledger would be truly impartial . Technology cannot be accused of bias in any situ ation. It is also devoid of any defects that humans can have in such a situation. Blockchain technology ensures the credibility of the information provided. Data saved in blockchain are irreversible and secured by complex cryptographic tools. Thanks to thi s, it can be confirmed once and for all that a given entity has published exactly such a document at a certain time. Figure 2 Trust via Blockchain, https://www.dreamstime.com/imprimir - image212196293 The difficulty in protecting intellectual property i s one of the problems that Digital Notary can potentially help with. The benefits of keeping registers in this form of the distributed ledger are the possibility of quick authorized access to them and the ability to automate transactions using intelligent contracts. An easy - to - imagine example can be confirming the authorship and time of the document's origin. Saving it together with the author's identifier in the blockchain would give proof of its existence and possession of it by the entry at a given time. Of course, this may apply to any digital documents including photos, films, novels, music recordings, etc. This could facilitate copyright or the priority of patent applications. Similarly, the authenticity of medical data can be secured. Blockchain Applicatio n Development – CA1 202 2 - 21133824 6 3. Technical Approach With the growth of blockchain popularity and the development of innovation, the ideas of blockchain technology go beyond making payments using cryptocurrencies. A digital public notary without leaving home? Two cryptographic mechanisms are used to ensure the user ’ s trust: • digital signatures based on a public key, allowing for authentication of transactions , • the hash function, with its solution, confirms that the action was performed. 3.1 SHA - 256 An important element of blockchain technology is the use of cryptographic mixing functions for many operations, such as mixing content. Hashing is a method of calculating a unique fixed - size format for input data of almost any size such as files, text or i mages and many more. Even the slightest change in the input data, for example, a single character will cause a complete change in the final result. The hash function is only one - way, and it is infeasible to reverse it, so cannot get a file from a hash. Jus t like you cannot get fruits back from the smoothie. Figure 3 . Hashing, https://computersciencewiki.org/index.php/One - way_function The calculation of any input that reproduces any predetermined output is impossible to compile. The Hash algorithm that i s used in Digital Notary is the Secure Hash Algorithm (SHA) algorithm with a 256 bits output size (SHA - 256) Many computers support this algorithm in software, which accelerates calculation. This algorithm has 32 bytes, shown in Figure 4 , as a 64 - character hexadecimal chain, which means that there is 2 256 = 115 792 089 237 316 195 423 570 985 008 687 907 853 269 984 665 640 564 039 457 584 007 913 129 639 936 possible values. The algorithm for SHA - 256, as well as others, is specified in the Fed eral Information Processing Standard (FIPS) 180 - 43. 1 1 National Institute of Standards and Technology, “ Secure Hash Standard (SHS) ” https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180 - 4.pdf Blockchain Applicatio n Development – CA1 202 2 - 21133824 7 Input Data SHA - 256 values N otary 41672dd1beaeb6ee7c293ab841073952c813ce450f323418c335c942b5d85845 n otary a0800997eb2fed3f3b33d86de629f548449450ecf40530106224132d616061be Table 1 . Example of mixing data using the SHA - 256 algorithm. Source: own design using SHA - 256 generator. Figure 4 Creating SHA - 256 hash for any file using JavaScript. 3.2 Public and private key Another important technology used in Digital Notary is the cryptography of the public/private key. The public key can be made public without reducing the safety of the process, but the private key must remain secret if the data is to be protect ed by cryptographic protection. Although there is a relationship between these two keys, the private key cannot be effectively determined based on knowledge of the public key. Key cryptography uses various keys from a pair of keys to specific functions, de pending on which service is to be provided. For example, with the digital signing of data, the cryptographic algorithm uses a private key to sign. The signature can then be verified using the appropriate public key. Blockchain Applicatio n Development – CA1 202 2 - 21133824 8 Use of public/private 2 key cryptograp hy in Digital Notary systems: • Private keys are used for digital transaction signing. • Public keys are used to generate addresses. • Public keys are used to verify signatures generated by private keys. To eliminate corruptible intermediaries Digital Notary u se s the cryptography of the public key and the open transaction register, which is saved in the chain. Any information that is located in the block must be encrypted through the key pair. Digital signatures are a source of public - key cryptography, which us es a pair of keys to ensure the integrity and the origin of the message, in other words, checks the authenticity of the information. Figure 5 . The process of safe digital signature and verification , Source: https://en.wikipedia.org/wiki/Electronic_signature This signature is unique to each data set and contains information about the sender, content and time of the event ( timestamp ). Simply put, it acts as a practically unique wax seal, which is used to authenticate the sender, gives credibility to content and prevents undeniable Timestamping is a way to prove that some information existed at a given moment. Using blockchain allows proving access to data in a way that cannot be challenged. For example, i f a person wanted to prove that owns a file, can encrypt the file and save the hash of that file as an annotation of the transaction. Then, if ever has to prove to have a file, it will be saved publicly throughout the blockchain. Other cases of use of time signatures in the blockchain include proving that the task was taken within a specified period, which proved the possession of a photo, confirmation of signing the contract or proving the occurrence of the event. 2 National Institute of Standards and Technology, “ Digital Signature Standard (DSS ) ” https://nvlpubs.nist.gov/nistpubs/fips/nist.fips.186 - 4.pdf Blockchain Applicatio n Development – CA1 202 2 - 21133824 9 4. Special resources required In additio n to online resources such as Stack Overflow, Reddit, GitHub and YouTube the following readings will be used throughout the project process. (i) Frontend Development Title : How To Code in React.js Author: Joe Morgan Publisher: Digital Ocean (i i ) Frontend Development Title: Learning React Author: Kirupa Chinnathambi Publisher: Pearson Education, Inc. (ii i ) Backend Development Title : Ethereum Blockchain Developer Guide Author: Thomas Wiesner Publisher: Thomas Wiesner (i v ) Backend Development Title : Blockchain Enabled Applications Author: Vikram Dhillon , David Metcalf , Max Hooper Publisher: Apress Media ( v ) Backend Development Title: Ethereum for Architects and Developers Author: Debajani Mohanty Publisher: Apress Media 5. Project Plan The process of creating a web - based application is not about only writing code. Before a beautiful site appears online and starts attracting a huge movement, needs to go through several complex stages, which people are generally not aware of. Creating a web application is included in a well - planned, comprehensive process, whose main goal is to provide a product that meets needs and requirements. It consists of several stages, during which need to ensure proper planning, product design and, what is particularly important, efficient code. Many projects are lost only because they have not been divided into friendly, imaginary parts, and these parts were not set for the deadline. The key is two elements, dividing the project into the right size stag es and tasks, and realistic estimation of the duration of individual tasks. Blockchain Applicatio n Development – CA1 202 2 - 21133824 10 Figure 6 Infographic c hart d ata of p roject p lanning of Digital Notary DApp . Source: own design Above can be found a detailed approach I took to splitting the workload up and also how in a nine - week sprint I will be able to complete the project. The project should be finished before the middle of August 2022 and will be carried out with almost zero financial outlays because it will be deployed on the Test Network using free too ls. The only expense I predict is the purchase of a domain. The project will be implemented in the cascading model because the list of functions has been decided in the analysis phase. The project will be implemented in five phases. The first and most impo rtant, but often ignored stages of website creation are analysis and planning which determines what the next stages will look like. In the very beginning, the most crucial is to understand the functioning of the project. Identification and analysis help to find the perfect solution. At the planning stage, is determined what the site's architecture will look like, what will be the division of elements on individual pages and what technologies will be needed. At the website design stage, user convenience and application accessibility are of key importance. It is, therefore, necessary to make sure that the site will be attractive to visitors. The coding stage is the point where the actual application is created. This process is divided into two parts: Frontend and Backend. Frontend, as the name suggests, is the development of the user interface. Backend, in turn, refers to the development of code related to queries to smart contracts and blockchain networks. Testing is probably the most routine part of the appli cation creation process. However, this does not make it less important than the previous phases. During this stage, a functionality test, utility test, performance test, and more are carried out. When the application is configured and the page is on the se rvers, it should be subjected to the last tests. At this point, the process of creating the application will end, but its development will not. The last stage is therefore management of the site and its further optimization and development. Blockchain Applicatio n Development – CA1 202 2 - 21133824 11 Figure 7 Digital Notary p roject management using Trello Source: own design The above shows a simple project management board found on Trello which I have implemented to control the flow of work done. The Trello board allow me to split the work up whil e also keeping an eye on the time frame, which will keep me on track throughout the project. This simple board allow me to update after each part was in progress or complete, it also included a timeline which kept the project progressing. During the develo pment of the application, I will be able to tick off tasks and keep a timeline using boards, these tasks could be changed to different labels. These boards allowed me to leave comments to gain a better understanding of the tasks as they are going on. Fi gure 8 Digital Notary reflective journal using WordPress and EC2 Amazon Web Services Blockchain Applicatio n Development – CA1 202 2 - 21133824 12 A reflective journal can be a notebook that students write and provide to their teacher from time to time. But probably a better solution is the journal written in the cloud because it facilitates access at any time and the student does not lose contact du ring checking. It can be constantly completed and created. WordPress is currently one of the most popular CMS systems in the world. Websites, portals, blogs and other types of applications based on the WordPress system are supported by different types of s ervers. Currently, hosting for WordPress is a very popular solution provided by many hosting companies. As a student, I get a grant of 100 dollars from AWS, so I decided to use it for my cloud journal Amazon Web Services is a powerful cloud processing pla tform that allows everyone to use the power of excellent Amazon infrastructure based on payment by actual use. EC2 is a processing platform in the AWS cloud that allows the creation of virtual machines and the launch of internet applications such as WordPr ess. 6. System Design The creation of the application should start with the preparation of the basic scheme of the program operation, as well as its graphic interface, which should be maximally functional and transparent to the user. For this purpose, th e free Balsamiq tool was used. Balsamiq is designed to prepare the application interface at its discretion. It provides the possibility of creating a prototype of the Graphical User Interface for popular mobile and web platforms. The program has a rich bas e of shapes and elements, buttons, and stripes that allow for creative projects. We will also find high - quality items here. In addition, the program has many different elements of GUI designed to create interfaces for many other platforms. Using this tool is very pleasant and simple. The use of this tool gave the possibility of a more effective and much simpler creation of the initial application interface. This is how a graphic interface is created. Based on the design approach, I decided that the site sho uld look like the following: Figure 9 Site map of Digital Notary DApp . Source: own design using Balsamiq The site map is an easy - to - understand flow of the website this allows for a greater understanding of what is required from the development phase. Firstly the homepage here will give a brief understanding to the users of the service and allow the user to navigate to various sections of the website and allows a user to upload files. This should be a friendly and welcoming area to tr y and attract users to further explore the site. Blockchain Applicatio n Development – CA1 202 2 - 21133824 13 Figure 1 0 GUI of the Home page of Digital Notary DApp . Source: own design using Balsamiq The about page will provide a service overview. This page will aim to allow the user of the site to explore and understand the goal and values of the service while also getting to know the functionality of the website. This page will have a mixture of images and texts well as show the services available. Figure 11 GUI of the About page of Digital Notary DApp . So urce: own design using Balsamiq Blockchain Applicatio n Development – CA1 202 2 - 21133824 14 The contact page allows the website user to get in contact with the developer about any issue they like. To be able to contact the developer the user must agree to the terms and conditions. The user enters their name and em ail Then the user enters the subject of their query and finally, the user enters their query in the text box. Figure 12 GUI of the Contact page of Digital Notary DApp . Source: own design using Balsamiq 6. 1 Use Case The use case is a graphic representation of functional requirements. Use case diagram presents the functionality of the system along with its surroundings. The use case is determined by a set of actions, each of which represents the interaction of elements from the system environment with the system itself. These actions are, in fact, system functions, which at the stage of identifying requirements and analysis are used to imagine, specify, create and document the expected behaviour of the system. The use c ases represent the functional requirement for the system as a whole. The use case includes the interaction of the actors and the system. The actor represents a set of roles played by users. It can be a person or an automated system. Each use case should be named in a way that will difference it from other use cases. Blockchain Applicatio n Development – CA1 202 2 - 21133824 15 Figure 13. Activity Diagram of Data Certification process in Digital Notary DApp. Source: own design After the user uploads a file evidence is obtained by creating a digital fingerprint in the form of a cryptographic hash, and by adding a trusted timestamping mechanism, defining the specific moment of the date and time in which it was created and add ing t o the blockchain. The hash constitutes the exact contents of the file uploaded. This means that the hash is used to verify that the file has not been manipulated or modified in a manner inconsistent with the author's intention Figure 14 Digital Notary Use Case Diagram . Source: own design using Visual Paradigm. Blockchain Applicatio n Development – CA1 202 2 - 21133824 16 Table 14 .1 - Connection via MetaMask Name: Connection via Metamask The initial conditions: The user is in the main view of the application. Description: The user wants to connect to the application Basic flow: 1. The Metamask extension prompts the user to enter a password. 2. The user enters the password. 3. The extension validates the entered password. 4. The user is connected to the application. Alternative flow: 4a. The password is incorrect and the user is asked to enter a correct password. Final conditions: The user is connected to the application through Metamask. Table 14 .2 – Upload file Name: Upload file The initial conditions: The user is connected and in the main view of the application. Description: The user wants to stamp proof a file. Basic flow: 1. The user uploads a file. 2. The algorithm SHA - 256 is calculating a hash from a file. 3. The hash is calculated an d displayed to the user. Alternative flow: 1a. System displays an error if the user fails to upload a correct file. Final conditions: The hash from a file is calculated. Table 14 .3 – Verify file Name: Verify file The initial conditions: The user is connected and in the main view of the application. Description: The user wants to verify a file. Basic flow: 1. The user uploads a file. 2. The algorithm SHA - 256 is calculating a hash from a file. 3. The hash is calculated and displayed to the user. 4. System displays to the user if the file was uploaded previously, and then verifies that the file is the same. Alternative flow: 4a. If the file is changed the system calculate another different hash. Final conditions: The file is verified. Blockchain Applicatio n Development – CA1 202 2 - 21133824 17 Ta ble 14 .4 – Calculate hash Name: Calculate hash The initial conditions: The user uploads a file. Description: The hash from a file is calculated to prove it or verify it. Basic flow: 1. The file is uploaded. 2. The algorithm SHA - 256 is calculating a hash from a file. Alternative flow: 1a. The correct file is not uploaded and the hash is not created. Final conditions: The hash from a file is calculated. Table 14. 5 – Interact with Blockchain Name: Interact with Blockchain The initial conditions: The user is connected and the file is uploaded and hashed. Description: Connection with blockchain using the Smart Contract to add timestamping mechanism, defining the specific moment of the date and time. Basic flow: 1. The Metamask extension prompts the user to finalise the transaction. 2. The user approves the payment. 3. The extension validates the fund on the user account. 4. The transaction is approved. Alternative flow: 4a. The transaction fails. Final conditions: Hash with a n immutable timestamp is added to the blockchain. 6. 2 Requirements Specification According to generally accepted software engineering processes, one of the first stages of producing a new project is to collect requirements. These subsections contain both functional and non - functional requirements. Functional Requirements These requirements are a set of all functionalities that have been mentioned so far, especially at the analysis stage. They describe all the functions that the system will provide. The user will be able to connect to web3 using a browser extension MetaMask. The user will be able to upload a file using the front end of the application. The evidence is obtained by creating a digital fingerprint in the form of a cryptographic hash, and by adding a trusted timestamping mechanism, defining the specific moment of the date and time in which it was created. Blockchain Applicatio n Development – CA1 202 2 - 21133824 18 The user will be able to verify a file using the front end of the application. When the same file is uploaded again, the same hash will be created and then verify that the file is the same. Calculate hash is a method of calculating a unique fixed - size format for input data of almost any size such as files, text or images and many more. The Hash algorithm that is used in Digital Notary is the Secure Hash Algorithm (SHA) algorithm with a 256 bits output size (SHA - 256). Interaction with blockchain, service allows for inclusion in the chain of cryptographic blocks information about the file selected by the user in the form of calcul ated hash. Non - functional Requirements The collection of these requirements describes what requirements for the system are to be met, in addition to functional requirements. They mainly focus on how to work, performance, safety, etc. Reliability and A vailability , the system should be available every day of the week twenty - four hours a day. The application may not have unhandled exceptions, each behavior potentially generates an error that must be properly served. Easy to use and with a pleasant appearance , t he application interface must be as simplified as possible. Individual items should be placed in places consistent with the design rules. The appropriate colours should be selected so that reading does not cause problems. Generally accepted iconography must be used so the users know what they are for. Icons and buttons should be large and visible enough. The use of the system should be intuitive and transparent to the user. The S ecurity and Credibility , service does not receive fil e s and it is not possible to read its content. The file itself is not available to the public and the SHA - 256 algorithm ensures the greatest cryptographic security of the transmitted information between the blockchain network nodes. Performance , the syste m should handle many users at one time. Synchronization with blockchain should run smoothly for all users connected simultaneously. Usability, the system is to meet at least 90% of functional requirements, especially regarding backend performance. Possib ility of expansion , the system should be designed in such a way that future development is as simple as possible. The application must be designed following the standards adopted when designing responsive applications. Blockchain Applicatio n Development – CA1 202 2 - 21133824 19 7 Technical Details Digital Notary Decentralized Application is an application with a backend in the form of a Smart Contract. The user interface is written in the JavaScript framework React which downloads and saves data on the blockchain network. The front end allows a user to upload a file. Connection to the Ethereum test network is made using the MetaMask plugin, which works with most browsers and injects a window.ethereum objects to the browser window, which is transferred to the Web3 library to communicate with the block chain. I do not would like to run a full node on my computer so to connect to the test network for data reading I chose the external, fully scalable API, Infura which allows me to have three projects for free. Infura provides the necessary tools so that th e application can work in Ethereum networks, without the need to run the complex infrastructure. Unfortunately, it is not without flaws, Infura is centralized, making it exposed to attacks that can limit its functionality and can also be used for censorshi p. So basically the application using the Infura is centralised, which breaks the concept of the entire blockchain, decentralisation and anonymity. Perhaps in the future, I will consider another way of communication, but at this moment Infura seems to be a reasonable and practical solution. Figure 15 The architecture of Digital Notary Decentralization Application . Source: own design 7. 1 Backend The backend will be powered by the Ethereum blockchain to implement the application because it is extremely popular among the creators of DApps and programmers, it has a large community, and it is very decentralised, thanks to which access to materials is really wide. Ethereum is the most popular platform for smart contracts and most blockchain applications. The Digital Notary back end will be programmed using Solidity, which is a language created especially for Ethereum Virtual Machine (EVM). It is not very difficult to learn, but due to the Turing completeness, it's hard to reach all potential and obvious mistakes. Blockchain Applicatio n Development – CA1 202 2 - 21133824 20 Figure 1 6 Part of Digital Notary S mart C ontracts using S olidity A smart contract is a mutual obligation of the parties saved in the form of a computer code, based on the assumption that if an X event occurs, then perform Y. For a framework to build a DApp I choose Truffle Suite. A truffle is a development too l for programmers creating projects in Ethereum. This tool is currently one of the most popular frameworks dedicated to implementation, testing, as well as launching decentralized applications based on Ethereum. Supporting processes in all layers of implem ented decentralized applications such as the back end and front end. This tool requires installation in the operating system. The advantage of using Truffle is working with my own independent IDE, in my case Visual Studio Code as well as the possibility of automating testing and deployment processes. Metamask is an application in the form of a browser extension, it not only allows storage and sending of tokens but is a gate to all decentralized applications operating in Ethereum networks. Such as Binance Smart Chain, Polygon, Polkadot and many more. It should be remembered that each transaction costs even in the case of the Ethereum test network and is required to have a small amount of Ether to use the service. The fee can be selected between low, medium and high. Advanced options can be entered to set the GAS limit and a maximum fee in GWEI to speed up transactions