## 2 Foundations of Blockchain, Ethereum, Smart Contracts, and Digital Wallets
Every Ethereum account consists of several key components [14]:  
* Transaction counter (nonce)--to prevent replay attacks;
* Balance of Ether (ETH)--the native cryptocurrency used for transaction fees;
* Smart contract code (if applicable);
* Persistent storage for contract-related data. There are two primary types of account within the Ethereum network: (i) externally owned accounts--controlled by private keys, allowing users to initiate transactions--and (ii) contract accounts--managed by deployed smart contract code, which executes autonomously in response to incoming transactions. A fundamental component of Ethereum is the use of smart contracts [3], which are self-executing programs designed to operate  
Figure 1: The operational framework of a blockchain. deterministically within the EVM. These contracts operate as part of the Ethereum network protocol and allow developers to implement automated, trustless interactions. Smart contracts can be written in multiple programming languages, each offering unique characteristics tailored to different use cases of the blockchain. The most widely used languages are Solidity [15], Vyper [16], and Fe [17]. A key component in the context of dApps and smart contracts is the generation of the Application Binary Interface (ABI) [18], which is created from the contract code. ABI enables the contract to communicate and interact with external applications by defining callable methods. This enables external applications to communicate with the contract in a language understood by the EVM. Before a smart contract can be deployed on the Ethereum network, it must first be compiled into low-level bytecode, which is then executed by the EVM. To streamline this process, developers can use a variety of tools and integrated development environments. Among the most widely used solutions are Remix [19], a browser-based IDE designed for Solidity development, and Hardhat [20], a modern development framework for compiling, testing, and deploying Ethereum smart contracts. Hardhat supports extensibility of plugins, mainnet forking, and advanced debugging capabilities, making it a preferred choice among developers for building production-grade decentralized applications. In summary, Ethereum has significantly expanded the capabilities of blockchain technology, enabling dApps that go far beyond financial transactions. With the EVM, smart contracts, and the dApp ecosystem, Ethereum provides developers with a powerful and flexible environment to create complex decentralized solutions. As adoption continues to grow, Ethereum's potential extends to multiple industries, making it a cornerstone of the Web3 revolution [21]. The final and highly significant component that needs to be introduced for the purposes of this paper is digital wallets. A cryptocurrency wallet is a specialized type of digital wallet designed exclusively for managing blockchain-based assets. Although certain digital wallets offer cryptocurrency storage capabilities, they lack the specialized security features and optimizations required to securely execute blockchain transactions, which are inherently supported by dedicated cryptocurrency wallets. The key differences between a digital wallet and a cryptocurrency wallet are presented in Table 1.  
Cryptocurrency wallets serve as interfaces for storing cryptographic keys, which are essential for accessing funds and authorizing transactions. The private keys stored within these wallets enable users to digitally sign transactions, thereby proving ownership of their Ethereum addresses and authorizing outgoing operations. However, the presence of a valid signature does not guarantee that an account possesses sufficient funds. The EVM performs final verification of the account balance and execution of the transaction during the processing phase. If the balance is insufficient, the transaction will revert automatically, even if it was correctly signed. Cryptocurrency wallets can be categorized according to