IGCSE Computer Science: Principles and Characteristics of Digital Currency | IGCSE计算机：数字货币原理与特点

📚 IGCSE Computer Science: Principles and Characteristics of Digital Currency | IGCSE计算机：数字货币原理与特点

Digital currency is a form of money that exists only in electronic form. Unlike physical cash, it has no notes or coins, and it is transferred using computers and networks. In this article, we will explore the core principles behind digital currency, especially cryptocurrency, and examine its key characteristics from an IGCSE Computer Science perspective.

数字货币是一种仅以电子形式存在的货币。与实物现金不同，它没有纸币或硬币，而是通过计算机和网络进行转移。在本文中，我们将从 IGCSE 计算机科学的角度，探讨数字货币（尤其是加密货币）背后的核心原理，并分析其主要特点。

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1. What is Digital Currency? | 什么是数字货币？

Digital currency is money that is stored and transferred electronically. It includes cryptocurrencies such as Bitcoin, as well as digital versions of government-issued money, known as central bank digital currencies (CBDCs). A digital currency does not need a physical object, such as a coin or a banknote, to represent value.

数字货币是以电子方式存储和转移的货币。它包括比特币等加密货币，也包括政府发行货币的数字版本，即中央银行数字货币（CBDC）。数字货币不需要硬币或纸币等实物来代表价值。

There are two broad categories:

数字货币可以分为两大类：

• Cryptocurrency – a decentralised digital currency that uses cryptography for security, for example Bitcoin and Ethereum.
• CBDC – a digital currency issued and controlled by a central bank, for example the digital yuan in China.
• 加密货币——一种使用密码学保障安全的去中心化数字货币，例如比特币和以太坊。
• 央行数字货币（CBDC）——由中央银行发行和控制的数字货币，例如中国的数字人民币。

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2. Key Technology: Blockchain | 关键技术：区块链

Most digital currencies rely on a technology called the blockchain. A blockchain is a distributed ledger that records every transaction across many computers. Each group of transactions is stored in a ‘block’, and blocks are linked together in a ‘chain’ using cryptographic hashes.

大多数数字货币依赖一种称为区块链的技术。区块链是一个分布式账本，跨多台计算机记录每一笔交易。每批交易存储在一个“区块”中，区块通过加密哈希链接成一条“链”。

Each block contains:

每个区块包含：

• A list of transactions – the actual payment data.
• A timestamp – the time when the block was created.
• A hash of the previous block – this links the blocks together and prevents tampering.
• A nonce – a number used in the mining process.
• 交易列表——实际支付数据。
• 时间戳——区块创建的时间。
• 上一个区块的哈希——用于将区块链接在一起并防止篡改。
• 随机数（nonce）——在挖矿过程中使用的数字。

Because every block contains the hash of the previous block, changing any single transaction would change every later block. This makes the blockchain very difficult to alter without detection.

由于每个区块都包含上一区块的哈希，修改任何一笔交易都会导致后续所有区块发生变化。这使得区块链极难在不被察觉的情况下被篡改。

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3. How Cryptocurrency Transactions Work | 加密货币交易如何运作

When a user wants to send cryptocurrency, they create a digital message containing the recipient’s address, the amount, and a digital signature. This message is broadcast to the network and grouped with other transactions into a candidate block.

当用户想发送加密货币时，他们会创建一条数字消息，其中包含接收方地址、金额和数字签名。该消息会被广播到网络中，并与其他交易一起组成一个候选区块。

Once the block is verified and added to the blockchain, the transaction is considered confirmed. The process can be summarised as:

一旦该区块被验证并添加到区块链中，交易即被视为确认。其过程可概括为：

Transaction → Broadcast → Verification → Block added → Confirmed

In IGCSE terms, you should remember that the system is peer-to-peer: there is no central server that holds all the data. Every node in the network keeps a copy of the blockchain.

在 IGCSE 考试中，你需要记住该系统是点对点（peer-to-peer）的：没有一台中央服务器保存所有数据。网络中的每个节点都保存一份区块链副本。

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4. Mining and Consensus Mechanisms | 挖矿与共识机制

New blocks are added through a process called mining. Miners compete to solve a difficult mathematical puzzle. In Bitcoin, the puzzle is to find a nonce such that the block hash is below a certain target. This is called Proof of Work (PoW).

新区块通过一个称为挖矿的过程添加。矿工竞争解决一个困难的数学难题。在比特币中，难题是找到一个随机数，使得块哈希低于某个目标值。这被称为工作量证明（PoW）。

For example, miners must find a value so that:

例如，矿工必须找到一个值，使得：

Hash(block header + nonce) ≤ Target value

There is no shortcut; miners must try many nonce values. Once found, the miner broadcasts the solution, and other nodes check it. This consensus mechanism ensures that everyone agrees on the same version of the blockchain.

这里没有捷径；矿工必须尝试许多随机数。一旦找到，矿工就会广播解决方案，其他节点对其进行验证。这种共识机制确保所有人对同一个区块链版本达成一致。

Another mechanism is Proof of Stake (PoS), where validators are chosen based on the number of coins they ‘stake’ or lock up. PoS uses much less energy than PoW.

另一种机制是权益证明（PoS），验证者根据他们“质押”或锁定的货币数量被选中。PoS 比 PoW 消耗的能源少得多。

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5. Public Keys and Private Keys | 公钥与私钥

Cryptocurrency uses asymmetric encryption. Each user has a public key, which acts like an address and can be shared freely, and a private key, which must be kept secret and is used to sign transactions.

加密货币使用非对称加密。每个用户拥有一个公钥，它像地址一样可以自由分享；还有一个私钥，必须保密，用于签署交易。

When a user sends money, they create a digital signature using their private key. Other users can verify that signature using the sender’s public key. This proves that the transaction really came from the owner.

当用户发送资金时，他们使用自己的私钥创建数字签名。其他用户可以使用发送者的公钥验证该签名。这可以证明交易确实来自所有者。

Key points for exams:

考试要点如下：

• Private key – kept secret, used for signing.
• Public key – shared openly, used for verification.
• Digital signature – proves authenticity and integrity.
• 私钥——保密，用于签名。
• 公钥——公开分享，用于验证。
• 数字签名——证明真实性和完整性。

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6. Characteristics of Digital Currency | 数字货币的特点

Digital currencies have several important characteristics that distinguish them from traditional money.

数字货币具有几个重要的特点，使其区别于传统货币。

Characteristic | 特点	Explanation | 解释
Decentralisation | 去中心化	No single authority controls the network. | 没有单一权威机构控制网络。
Immutability | 不可篡改性	Once recorded, transactions cannot be easily changed. | 交易一旦记录，就很难更改。
Transparency | 透明性	The ledger is public and can be inspected by anyone. | 账本是公开的，任何人都可以查看。
Pseudonymity | 假名性	Users are identified by addresses, not real names. | 用户通过地址而非真实姓名识别。
Limited supply | 供应有限	Many cryptocurrencies have a maximum cap, e.g. Bitcoin’s 21 million. | 许多加密货币有最大供应上限，例如比特币的 2100 万枚。

These characteristics come from the design of the underlying protocols and cryptographic algorithms.

这些特点来源于底层协议和密码算法的设计。

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7. Advantages of Digital Currency | 数字货币的优点

Digital currencies offer several benefits over traditional banking and cash systems.

数字货币相比传统银行和现金系统具有若干优势。

• Lower transaction costs – especially for international transfers, because there is no intermediary bank.
• Fast transfers – payments can be processed in minutes even across countries.
• Financial inclusion – people without bank accounts can use a smartphone and an internet connection.
• Security – cryptography makes it difficult for criminals to forge transactions.
• No inflation by central banks – in some cryptocurrencies, the supply is fixed, so it cannot be increased arbitrarily.
• 较低的交易成本——尤其是国际转账，因为没有中间银行。
• 转账速度快——即使是跨国支付，也可能在几分钟内完成。
• 金融包容性——没有银行账户的人也可以使用智能手机和互联网。
• 安全性——密码学使犯罪分子难以伪造交易。
• 央行无法随意制造通胀——在某些加密货币中，供应量固定，不能任意增加。

From a computer science viewpoint, these advantages arise from clever use of networking, encryption, and distributed systems.

从计算机科学的角度来看，这些优势源于对网络、加密和分布式系统的巧妙运用。

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8. Disadvantages and Risks | 缺点与风险

Despite the benefits, digital currency also has significant disadvantages and risks that you should be able to discuss in exams.

尽管数字货币有诸多好处，但它也存在严重的缺点和风险，你应该在考试中能够讨论这些问题。

Volatility | 波动性

The value of cryptocurrencies can change dramatically in a short time. This makes them risky as a store of value.

加密货币的价值可能在短时间内剧烈变化。这使其作为价值储存手段具有风险。

Energy consumption | 能源消耗

Proof of Work mining requires huge amounts of electricity. Bitcoin mining, for example, consumes more energy than some small countries.

工作量证明挖矿需要大量电力。例如，比特币挖矿消耗的能源超过一些小国家。

Illegal use | 非法使用

Because transactions are pseudonymous, criminals can use cryptocurrency for money laundering, ransomware, or buying illegal goods.

由于交易具有假名性，犯罪分子可以利用加密货币进行洗钱、勒索软件攻击或购买非法商品。

Loss of private key | 私钥丢失

If a user loses their private key, they lose access to their funds forever. There is no central authority to recover it.

如果用户丢失了私钥，他们将永远失去对资金的控制权。没有中央机构可以帮助恢复。

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9. Cryptocurrency vs CBDC | 加密货币 vs 央行数字货币

It is important to distinguish between decentralised cryptocurrencies and central bank digital currencies. They are both digital, but their principles are very different.

区分去中心化的加密货币和央行数字货币非常重要。它们都是数字形式，但原理差异很大。

Feature | 特性	Cryptocurrency | 加密货币	CBDC | 央行数字货币
Issuer | 发行方	No central issuer | 无中心发行方	Central bank | 中央银行
Control | 控制	Decentralised | 去中心化	Centralised | 中心化
Value stability | 价值稳定性	Often volatile | 通常波动大	Stable, same as fiat currency | 稳定，与法定货币等值
Anonymity | 匿名性	Pseudonymous | 假名性	Usually traceable | 通常可追踪

For IGCSE, remember that CBDCs are not cryptocurrencies, even though both use digital technology.

对于 IGCSE 考试，请记住 CBDC 不是加密货币，尽管两者都使用数字技术。

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10. The Future of Digital Currency | 数字货币的未来

Digital currency is still evolving. Many governments are researching or launching their own CBDCs. At the same time, blockchain technology is being used outside finance, for example in supply chain tracking and digital voting.

数字货币仍在发展之中。许多政府正在研究或推出自己的央行数字货币。与此同时，区块链技术也被用于金融以外的领域，例如供应链追踪和数字投票。

However, challenges remain: scalability, regulation, energy use, and user education. A key question is whether digital currency will replace cash entirely. Most experts believe that cash will still exist for the near future, but the use of digital money will continue to grow.

然而，挑战依然存在：可扩展性、监管、能源消耗以及用户教育。一个关键问题是数字货币是否会完全取代现金。大多数专家认为，在不久的将来现金仍会存在，但数字支付的使用将继续增长。

For computer scientists, the principles behind digital currency — hashing, consensus, encryption, and distributed systems — are more important than the price of any single coin.

对于计算机科学家而言，数字货币背后的原理——哈希、共识、加密和分布式系统——比任何单一币种的价格都更为重要。

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11. Exam Tips | 考试要点

Here are some common questions and key points to remember for your IGCSE Computer Science exam.

以下是一些常见问题以及 IGCSE 计算机科学考试中需要记住的关键点。

• Define digital currency: money that exists only in electronic form.
• Explain the role of a blockchain: a distributed, tamper-resistant ledger.
• Describe a hash function: it takes an input of any size and produces a fixed-length output.
• State one use of a private key: signing transactions.
• Compare Proof of Work and Proof of Stake: PoW uses computation, PoS uses staked coins.
• Give one advantage: lower transaction fees. Give one disadvantage: price volatility.
• 定义数字货币：仅以电子形式存在的货币。
• 解释区块链的作用：一个分布式、防篡改的账本。
• 描述哈希函数：它接受任意大小的输入，并产生固定长度的输出。
• 说明私钥的一种用途：签署交易。
• 比较 PoW 与 PoS：PoW 使用计算，PoS 使用质押的币。
• 给出一个优点：较低的交易费用。给出一个缺点：价格波动较大。

Remember to use the correct terminology in your answers, such as ‘peer-to-peer’, ‘consensus mechanism’, and ‘distributed ledger’.

在答题时，请使用准确的术语，例如“点对点”、“共识机制”和“分布式账本”。

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Published by TutorHao | Computer Science Revision Series | aleveler.com

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