Cryptonomy

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Cryptocurrencies are digital assets that use cryptography to authorize transactions and are usually recorded on a shared ledger, the blockchain. They let you transfer value over the internet, often without a bank as an intermediary, but security, cost and the degree of decentralization vary from network to network.What cryptocurrency is in practiceImagine sending a digital amount to someone without your bank having to notify theirs. On a decentralized network, recording and checking are handled by computers that follow shared rules. You aren’t sending a file that anyone can copy at will: the network checks that the same units aren’t spent twice.Bitcoin was the first cryptocurrency to work as a decentralized system of this kind. Satoshi Nakamoto published its white paper in 2008, and the network launched in 2009. Other networks followed, with different uses and trade-offs.The balance in your banking app is also digital, but it is a claim against the bank. A cryptocurrency like Bitcoin is not a bank deposit, a company share or a claim redeemable in euros.How cryptocurrencies workThe blockchain and transaction checksA blockchain is a ledger in which transactions are grouped into blocks that are cryptographically linked to one another. On public networks, many computers, called nodes, maintain and check copies of the data according to the protocol’s rules.Picture a shared accounting ledger that doesn’t just sit in one accountant’s drawer. Many participants can check whether an entry is valid. Changing old entries becomes difficult when the network is sufficiently secure, not because blockchain is some technology that rules out every attack.What happens when you send cryptoThe wallet creates a transaction with a recipient, an amount and a network fee.You sign it digitally with your private key, without revealing it.The transaction is broadcast to the network and checked.Once accepted, it is recorded and gains confirmations or reaches finality, depending on the protocol.Speed and fees are not the same everywhere. They depend on the network, congestion and the transfer method. An international transaction can be cheap, but that isn’t automatically true for every cryptocurrency.Mining and stakingNot all cryptocurrencies are created through mining. On Bitcoin, the Proof of Work mechanism requires computational work from miners who compete to add blocks. The reward includes new coins, according to the protocol, and transaction fees.In practice, Bitcoin mining requires specialized equipment and comes with electricity costs. A home computer is not a realistic promise of easy income.Other networks, such as Ethereum, use Proof of Stake. Validators lock up crypto through staking to help secure the network. Staking is not bank interest: it can involve withdrawal restrictions, penalties and the risk of losing capital.Bitcoin, Ethereum, coins and tokensBitcoin is used to transfer and hold digital value. Ethereum also supports smart contracts, which are programs that run on the network. Its native currency is ether, with the ticker ETH.One distinction matters here: not every cryptocurrency has its own blockchain. A native currency, usually called a coin, belongs to its own network. A token can be issued on an existing blockchain and serve an application, a governance process or another purpose.The existence of a token doesn’t prove that a project needs one. We look at whether it has a real function and who controls its issuance, upgrades and distribution.Where the value of cryptocurrencies comes fromThe price is set by supply and demand in the markets. It is affected by utility, network security, circulating supply, future issuance, liquidity and expectations. Speculation can also carry a lot of weight.Limited supply isn’t enough on its own. Think of a rare item nobody wants: scarcity doesn’t guarantee it a buyer. Likewise, a useful application doesn’t necessarily mean its token gains value.To read a valuation correctly, keep these apart:Unit price: how much one coin costs, for example in euros.Market cap: price times circulating supply, not money that has been deposited into the project.Liquidity: how easily a trade can be made without moving the price much.Dilution: how new issuance or token unlocks change the available supply.A coin with a low unit price is not necessarily “cheap.” For the value in euros, the exchange rate also matters when the market you follow shows prices in dollars.What are stablecoinsStablecoins are tokens that aim to keep a stable exchange rate with a currency or another asset. USD Coin, for example, aims to stay pegged to the US dollar. There are different models, using reserves, crypto collateral or algorithmic mechanisms.A stable target peg does not mean guaranteed safety. There are reserve, issuer, redemption and de-peg risks. For someone who budgets in euros, a dollar stablecoin also carries currency risk.Holding a stablecoin doesn’t automatically earn rewards. Any yield comes from additional services or protocols with their own risks, and it is not the same as protected bank savings.Wallets, exchanges and control of your moneyA digital wallet manages the keys you use to control assets on the blockchain. The coins don’t sit as files on your phone. The private key authorizes transactions and must stay secret.With self-custody, you manage the keys. The seed phrase (recovery phrase), where one is used, lets you restore access. Anyone who gets hold of it can control the corresponding funds, so never give it to supposed tech support.With custody on an exchange, the provider manages the keys. Services such as Binance offer trading and custody, but they add the risk of the provider failing, suspending withdrawals or being hacked. This particular link contains a referral code and is not a recommendation to use the service.The ability to fully control your digital assets comes with full responsibility for their keys.To move funds to a regular bank account, you usually convert to euros first and then withdraw through a supported provider. Fees, limits and checks vary.Where they are used and what the risks areUses include payments where crypto is accepted, donations, international transfers and decentralized finance (DeFi) applications. With cards that convert crypto into euros, the merchant may receive euros rather than crypto.Most public blockchains are pseudonymous, not anonymous. Transactions are visible, and addresses can be linked to identities. Blockchain transparency does not rule out scams, price manipulation or key theft.The main pitfalls are high volatility, fake platforms, software bugs and sending to the wrong address or network. A confirmed transfer usually can’t be reversed like a card payment. Promises of “guaranteed returns” call for extra skepticism.Greek cryptocurrencies and the rules in GreeceThe term “Greek cryptocurrencies” usually describes projects with a Greek team or community. Greek origin is not a certification, a state guarantee or proof of trustworthiness. We look at documentation, a working product, admin privileges and token distribution, not just where the creators come from.For users in Greece, the EU’s MiCA regulation sets rules for specific crypto-assets and service providers. It doesn’t cover every product in the same way, and it doesn’t guarantee a token’s value or that you’ll get your money back.For tax treatment, you need to check the current provisions and AADE (Greece’s Independent Authority for Public Revenue) guidance with an accountant. Keep a record of transactions, fees and valuations in euros. Transferring money to your bank is not the only event that may need to be looked at for tax purposes.Our takeWe consider the ability to transfer value and keep personal control without being forced to depend on a provider to be a real innovation. We don’t believe, however, that every problem needs a blockchain or that every token justifies its existence. The question is who controls the system, what it offers and what can go wrong.Frequently asked questionsAre all cryptocurrencies decentralized?No. Concentration among validators, in token holdings or in admin privileges can give significant control to a few participants.Do I need to buy a whole Bitcoin?No. Bitcoin is divisible into smaller units. Minimum transaction amounts and fees depend on the service and the network.Can a cryptocurrency lose all its value?Yes. A collapse in demand, fraud, technical failure or a lack of liquidity can lead to a total or near-total loss.What happens if I lose my wallet?With self-custody, recovery depends on whether you still have the necessary keys or the seed phrase. If they are lost for good, there is usually no central authority that can restore them.Are cryptocurrencies the same as the digital euro?No. A central bank digital currency is issued under the responsibility of the relevant monetary authority. Bitcoin works with a different model of issuance and control.

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Recording and confirming transactions on a blockchain requires a consensus mechanism.

A blockchain is a shared digital record in which entries are organized into blocks linked to one another with cryptography. Instead of relying solely on a central administrator, a network of computers maintains and checks the record using shared rules. Blockchain technology makes it hard to alter the history after the fact, but that does not mean every application of it is secure or decentralized.What is blockchain: an everyday exampleThink of a building’s shared-expenses ledger that is kept not only in the property manager’s office but also as copies held by different residents. Each new page is added after being checked against agreed rules and includes a digital fingerprint of the previous page. If someone secretly changes an old entry, the inconsistency can be detected.That is the basic idea behind a chain of blocks, or blockchain. The analogy has its limits: a real network doesn’t decide by a simple residents’ vote, and it doesn’t guarantee that what was recorded matches reality.Blockchain belongs to the broader family of distributed ledger technology (DLT). The ledger is the record of entries. “Distributed” means it is kept in multiple places, not automatically that nobody controls it.How blockchain technology worksBlocks and the digital fingerprintA block contains transactions or other records, plus data that link it to the network’s history. A hash function gives the data a digital fingerprint, called a hash. If the data change, the fingerprint changes too.Each new block includes a reference to the fingerprint of the previous one. That is how the chain is formed. A hash is neither a digital signature nor encryption: it helps detect changes, but it does not hide the content.Nodes and consensus rulesThe computers that take part in the network are called nodes. Depending on their role, they relay transactions, store data and check whether the rules are being followed. Not every node necessarily keeps the entire history.The consensus mechanism determines how the network agrees on the order and acceptance of entries. There is no single “the majority of users approves” rule. What matters is what each protocol specifies and what resources are required to participate.Proof of Work and Proof of StakeIn Proof of Work (PoW), which Bitcoin uses, miners compete with computational work to add blocks. The process requires energy and equipment, while nodes independently verify that the blocks are valid.In Proof of Stake (PoS), validators lock up cryptocurrency through staking and take part in producing or confirming blocks. The exact rules and penalties vary by network. In both cases, security depends on the design, the distribution of power and how the system actually operates.A blockchain transaction in practiceImagine you are sending crypto to a friend. Your wallet creates the instruction, but it doesn’t move a file the way you would send a photo in a message. The network updates its shared record according to its rules.The wallet creates the transaction with the recipient’s address and the amount.The transaction is signed with your private key, proving authorization without revealing the key.It is broadcast to the network and checked, among other things, for a valid signature and available funds.Once it is included in an accepted block, it becomes part of the history.Depending on the protocol, additional confirmations or finality rules reduce the chance of it being reversed.A wallet mainly manages the keys that let you use the funds. It does not store coins the way a wallet holds banknotes. Fees and confirmation times also depend on the network and how congested it is.Blockchain, Bitcoin and smart contractsBlockchain is the technological structure, while Bitcoin is a specific network and its cryptocurrency. They are not synonyms. Nor does every blockchain application need a tradable token.Some networks, such as Ethereum, support smart contracts: programs that carry out actions according to predefined rules. Think of a vending machine that hands over a product once the conditions are met. Automation, however, does not guarantee that the code was written correctly.Smart contracts are not a required component of every blockchain, and they are not necessarily the same as legal contracts. When they need external data, such as delivery information for a product, they rely on data feed services (oracles). That brings back the question of whom we trust.Public and private blockchainsOn a public permissionless network, users can generally transact without approval from a central administrator. That does not mean every technical function is available without conditions or cost.On a permissioned network, an organization or consortium chooses the participants and their rights. Such a system can serve business needs, but it does not necessarily offer the decentralization of an open network. How public the data are and who is allowed to participate are separate questions.Where it’s useful and when it’s overkillThe Cryptonomy team believes the real question is which problem blockchain solves better than a conventional database. When independent organizations need a shared history without handing full control to one of them, it is worth considering.Transferring digital value: the ability to transact on open networks without a central ledger administrator.Supply chain: a shared record of the production, shipping and delivery stages.Certificates and documents: checking whether a digital file matches a recorded fingerprint.Programmable services: applications that execute transactions based on rules through smart contracts.Think of a Greek cooperative that wants to record the journey of its olive oil all the way to the buyer. A shared history can help participants agree on the entries. But if someone declares a false origin, the blockchain won’t check what’s inside the container on its own.If one business controls all the records and everyone trusts it, a conventional database may be simpler, faster and cheaper. Also, recording a creative work does not by itself prove intellectual property or prevent it from being copied.Advantages and risks, without the hypeOn the right networks, blockchain offers a shared verifiable history, the ability to check it independently and resilience against the failure of a central point. It can also cut down on record reconciliation between organizations. But it is not inherently faster or cheaper than every other system.Transaction throughput, fees and energy consumption vary significantly. Software bugs, vulnerable smart contracts, concentration of control and attacks remain real risks. The difficulty of changing old records rests on specific technical and economic conditions, not on an absolute guarantee.For users, network security does not mean wallet security. Key theft, fake websites and wrong addresses can lead to losses. There is usually no central authority that will reverse a valid transaction because a mistake was made.Is it anonymous, and what does it mean for users in Greece?On public networks, transactions are usually visible. Bitcoin is pseudonymous: addresses appear instead of names, but they can be linked to people, for example through identity verification services. Cryptography does not mean that all data are hidden.For applications in Greece and the EU, storing personal data in a public record that is hard to modify raises data protection issues. One approach is to keep the documents themselves off-chain and record only their fingerprints, though that doesn’t automatically solve every legal issue.For users in Greece, the technology also does not remove any obligation to declare or document transactions to AADE (Greece’s Independent Authority for Public Revenue), where such obligations apply. We see value in the ability to verify independently, but we judge each application on its own: who controls the network, what is actually being verified and who bears the risk?Frequently asked questionsWhat does blockchain mean?It means a “chain of blocks.” It describes a record in which groups of entries are linked one after another with cryptographic fingerprints, so changes to the history become detectable.What is the difference between blockchain and Bitcoin?Blockchain is a technological structure for recording data. Bitcoin is a specific network that uses it, as well as the cryptocurrency transferred on that network.Can a blockchain be hacked?No system is invulnerable. Security depends on the protocol, the participants and the implementation, and wallets and applications can be hacked even when the underlying network works correctly.Can a transaction be deleted?As a rule, a finalized transaction cannot be deleted by asking an administrator. Possible chain reorganizations or special interventions depend on the network and are not a transaction cancellation service.Do I need to buy crypto to use a blockchain?Not always. Some services let you read and verify data without buying anything, while sending transactions on many public networks requires a fee paid in the network’s cryptocurrency. In other applications, the provider covers the cost.