Bitcoin Security – Why Is Your Bitcoin Safe?

If you have ever heard the phrase "not your keys, not your coins", you know that security is the top priority in Bitcoin. Bitcoin security does not mean just keeping your phone locked. The foundation is cryptography, a decentralised network, and the fact that no third party has access to your assets. In this article, we will look at why Bitcoin is so resilient, what numbers stand behind its protection, why it cannot be shut down or frozen, and how you can use it safely too.

What Actually Protects Bitcoin? Cryptography and the Power of 2²⁵⁶

At first glance, it may seem that Bitcoin is only protected by an app on your smartphone. In reality, the security is backed by cryptography – a mathematical science that encrypts your private keys in a way that makes them practically impossible to break. Bitcoin uses the so-called SHA‑256 algorithm. Every Bitcoin wallet has a unique private key derived from a random 256‑bit number.

Why Is 2²⁵⁶ Such an Enormous Number?

You might think: "256 bits, that sounds like a pretty small number." In reality, however, it represents a number of possible combinations that is truly incomprehensible. If we compared each of these combinations to a single grain of sand, 2²⁵⁶ would represent more sand than the number of atoms in everything we can see – planets, stars, galaxies. If you had to pick one specific grain of sand somewhere in the entire universe and I had to guess which one, it would take longer than the age of the universe.

If you have a 24-word wallet, its entropy – or "randomness" – corresponds to exactly 2²⁵⁶. Even a 12-word seed has 2¹²⁸ combinations, which is still an astronomical number. This is why hacking a private key with a brute-force attack is practically impossible. If anyone claims otherwise, imagine having to fly across the entire universe, touch a random atom, and you would have to guess exactly which one it was – that is precisely what guessing such a key involves.

Hashing and Proof‑of‑Work

Transactions in Bitcoin are added to the blockchain through mining. Miners use computing power to solve mathematical puzzles that could not be cheated without a great deal of energy. These puzzles use the SHA‑256 hashing function. Simply put: a miner takes transactions and tries to find a certain hash beginning with a set number of zeros. This requires enormous computing power. When someone succeeds, a new block is added to the chain and the miner receives a reward.

The more miners in the network, the higher the hashrate – the total number of computations the network performs per second. In 2025, the hashrate was around one zettahash per second (1 ZH/s), meaning more than 1,000,000,000,000,000,000,000 (10²¹) hashes every second. This enormous computing capacity ensures that it is not feasible for any attacker to control more than half the network's power, which would be required for a 51% attack. Attacks are expensive and economically unfavourable – an attacker would have to buy or control the majority of the world's computing hardware, pay for electricity, and still risk being disconnected by other miners afterwards.

Why Can't Bitcoin Be Shut Down?

Internet services typically operate from a single location – if you shut down the server, the service stops working. Bitcoin is different. It is a network of thousands of nodes scattered across the entire world. Each node stores a copy of the blockchain and independently verifies new transactions. If some nodes go offline, the rest of the network continues.

Resilience Against Outages and Regulations

When China banned mining in 2021, the hashrate briefly dropped, but miners relocated to the United States, Kazakhstan, and Russia, and the network quickly recovered. Stories like this prove that Bitcoin cannot simply be unplugged. Completely shutting down the network would require turning off every node on the planet – which is not realistic. Even if the internet were shut down, there are alternative transmission routes: satellite transmission (Blockstream satellites), radio networks, or sending transactions via SMS. The network can survive even major infrastructure outages. For comparison: a standard banking system depends on a central server, which becomes fully non-functional in the event of an outage.

Nodes, Miners and Consensus

Nodes are ordinary computers that store a copy of the blockchain, and miners are specialised computers that collect transactions and search for new blocks. Together they ensure consensus – the majority of nodes agree on which block is valid. If someone submits an invalid block or transaction (for example, an attempt to freeze someone else's account), the other nodes simply reject it. There is no central admin who could block anyone's account. Your wallet communicates directly with the network, and the network confirms transactions according to pre-defined rules.

Can Your Bitcoins Be Frozen or Confiscated?

If you own a regular bank account, the bank or government can freeze your funds without your consent. With Bitcoin, this is not possible because no central institution is involved in the process. Your access to your coins is determined solely by whether you know your private key (seed). As long as you do not reveal it to anyone, no one can misuse it.

Your assets cannot be stolen from the network with a single click. There is no central database of accounts that governments or banks could block. Even if someone physically seized your device, as long as you remember your 12- or 24-word passphrase, you can access your assets from any other device. Your wallet exists in the form of words – codes – not as physical gold or cash that customs officers could confiscate. In extreme cases, people fleeing a country have written their seed on paper or memorised it, and upon reaching safety recovered their coins. This is why Bitcoin is often referred to as a portable digital vault.

Quantum Computers: A Real Threat or Science Fiction?

The media frequently carry reports that quantum computers will destroy Bitcoin. It is true that quantum computers have the potential to solve certain tasks exponentially faster than classical computers. In terms of the encryption used in Bitcoin, the algorithms most at risk are those based on elliptic curves (ECDSA), which are used to sign transactions. However, breaking them would require a quantum computer capable of running Shor's algorithm on 256‑bit keys.

Expert estimates vary, but the most commonly cited figure is that breaking ECDSA would require approximately 2,330 to 2,600 logical qubits. Each logical qubit is in turn composed of thousands of physical qubits to compensate for errors and instability. In practice, this would require millions or even tens of millions of physical qubits. The largest existing quantum computers today achieve on the order of hundreds of physical qubits. Technology with millions of logical qubits does not yet exist and, according to experts, is decades away.

Even if a quantum computer were to break ECDSA, it would be a problem for the entire world – not just for Bitcoin. Banking systems, internet connections, medical records – most of them use the same or similar encryption. This is precisely why post-quantum cryptographic algorithms are being gradually tested and implemented. The Bitcoin community is also preparing solutions: for example, transitioning to addresses beginning with bc1 (SegWit and Taproot), which limit the exposure of public keys, or using algorithms such as Dilithium or Falcon. If quantum computers ever arrive, Bitcoin can transition to a more secure version of signatures through a software update. It will be a challenge, but all systems in the digital world will need to adapt equally.

Recommendations for Your Personal Security

Even though the Bitcoin network is extremely resilient, the security of your coins depends on how you look after them. The following tips will help you minimise risks:

• Use a hardware wallet: Hardware wallets, such as Trezor, protect your private keys in an offline environment. They are easy to use and significantly reduce the risk of being hacked.
• Write down your seed offline: Write your 12- or 24-word seed with a pen on paper or a metal plate. Never photograph it or send it by email.
• Create multiple backups: Have at least two seed backups stored in different secure locations, for example at home in a safe and with a trusted person. If you want extra security, you can use more advanced methods such as Shamir Backup (splitting the seed into multiple parts) or a multisig wallet.
• Protect devices with a password and 2FA: If you use a software wallet, set a strong password and two-factor authentication. Keep your system and apps updated to reduce the risk of malware.
• Never reveal your seed to anyone: Keep your seed phrase to yourself. No legitimate service or exchange will ever ask you for it.
• Be careful on public Wi‑Fi: When accessing your wallet, use mobile data or a trusted connection instead. Public networks are easily exploited.

Hardware Wallets and Trezor

Hardware wallets are a small investment that can save you a lot of worry. Trezor is one of the most well-known and trusted devices. It is open‑source, manufactured in Europe, and supports features such as Shamir Backup and multiple passphrases. If you decide to get a hardware wallet, we recommend buying directly from the manufacturer or an authorised reseller and always checking the hologram on the packaging. Be careful not to end up with cheap clones – security is truly not something to underestimate in this case.

Frequently Asked Questions (FAQ)

Is it possible to break Bitcoin using a quantum computer?

Theoretically, an extremely powerful quantum computer could threaten current digital signature methods. Research shows, however, that this would require thousands of logical qubits and millions of physical qubits, which is unavailable today and will likely remain so for the next few decades. Moreover, Bitcoin and other systems are already preparing for post-quantum algorithms.

Can the government freeze my Bitcoins?

No. Bitcoin has no central authority that could stop your account. Governments can influence exchanges or banks, but if you hold your coins in your own wallet and know the seed, no one can seize them without your consent.

Is it safe to carry Bitcoin across borders?

Yes, and this is one of Bitcoin's greatest benefits. You do not need to carry any physical gold or cash. All you need is to remember or have written down your seed. When travelling, simply do not show your seed phrase to anyone; upon arriving at your destination, just restore it in your wallet.

What is the hashrate and why does it matter?

The hashrate is the total computing power that miners dedicate to solving cryptographic puzzles. A higher hashrate means more security – it would not be worth an attacker's while to pay for the energy and hardware needed to control the network. Bitcoin's hashrate has been around one zettahash per second since 2025, which is an astronomical level of power.

Can individuals change the rules set in Bitcoin?

The network's rules are embedded in the code, and anyone who wants to change them must convince the majority of users, miners, and nodes to switch to a new version of the software. In practice, it is almost impossible for an individual to push through a change that would harm the rest of the community. Decentralisation means that change requires broad consensus.

Even though Bitcoin and its technology may seem complex, the bottom line is simple: the security it offers is unrivalled. The combination of cryptography, decentralisation, and economic incentives creates a system that is difficult to stop, hack, or freeze. Learn the basic principles, use proven tools such as hardware wallets, and your Bitcoin will be safe for many years to come.