Crypto Tech Explained: Blockchains, Layer 2, ZK Proofs and Quantum Risk
The technology under every token, and what’s changing in it.
Prices get the headlines, but they sit on top of software. Network upgrades change what a chain can do and what it costs to use, and a single bug can wipe out a protocol overnight. This hub explains the main building blocks in plain language and tracks the upgrades that matter, with links to our latest tech coverage.
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How a blockchain keeps its records honest
A blockchain is a ledger copied across thousands of independent computers. New transactions are grouped into blocks, and each block carries a cryptographic fingerprint, or hash, of the one before it. Changing an old transaction would change its hash and break every block after it, so rewriting history means out-working the rest of the network. On Bitcoin or Ethereum that would cost far more than it could ever earn.
Proof of work vs proof of stake
Bitcoin uses proof of work. Miners spend electricity racing to solve a puzzle, and the winner adds the next block. Cheating would cost more in power than it pays. Ethereum switched to proof of stake in September 2022. Validators lock up ETH as collateral, earn rewards for honest work and lose part of their stake if they cheat. The Ethereum Foundation estimates the switch cut the network’s energy use by about 99.95%. Most newer chains, Solana included, use some form of proof of stake.
Smart contracts
A smart contract is a program stored on a blockchain that runs exactly as written when someone calls it. Uniswap’s token swaps, Aave’s loans and every stablecoin transfer on Ethereum run this way, with no company approving each step. The catch is that code is law in both directions. When a contract has a bug, the money it holds can be drained in a single transaction, and there’s rarely a way to undo it. Audits have improved a lot, and AI tools now help find flaws, as our report on AI crypto security tools shows. But exploits still cost users heavily every year.
Open-source code helps outsiders check what a contract does, which is why we covered the open-source memecoin launchpad that published its full contract.
Layer 2: scaling Ethereum
Ethereum’s base layer handles a limited number of transactions per second, and fees spike when demand is high. Layer-2 networks such as Arbitrum, Optimism and Base process transactions off the main chain and post compressed results back to it, so users pay a fraction of the fee while still settling on Ethereum. Optimistic rollups assume batches are valid and allow a challenge window, usually seven days. ZK rollups, such as zkSync and Starknet, attach a mathematical proof instead, so they don’t need the waiting period.
The Fusaka upgrade, live since December 2025, added PeerDAS and cut the cost for rollups to post their data. Cheaper data hasn’t saved every network, though. Several smaller layer 2s have shut down this year, which we looked at in Ethereum’s layer-2 economics.
Zero-knowledge proofs and privacy
A zero-knowledge proof shows that a statement is true without revealing the data behind it: that a batch of 10,000 transactions is valid, say, or that a payment balances without exposing the amount. That makes ZK proofs the base for both ZK rollups and privacy tools. Public blockchains show every transaction by default, which is a problem for banks and businesses. Ethereum projects aimed at institutions are building on ZK proofs (see Ethereum’s institutional privacy push), and a new proposal would bring Zcash-style shielded transactions to Bitcoin.
AI and crypto
The overlap is real now, and it cuts both ways. AI models speed up code audits, but attackers use the same tools to find weaknesses faster, a trade-off we covered in AI and Bitcoin security. Meanwhile, Bitcoin miners are renting their power and data centres to AI companies. The biggest deal so far is Riot Platforms’ US$9.1 billion lease with Anthropic.
Quantum computing: a long-term risk
Bitcoin and Ethereum signatures rely on elliptic-curve cryptography. A large enough quantum computer running Shor’s algorithm could, in principle, work out a private key from a public key. Today’s machines are nowhere close. Google’s Willow chip, unveiled in December 2024, has 105 physical qubits, while estimates for breaking a Bitcoin key run to millions of error-corrected qubits. NIST published its first post-quantum cryptography standards in August 2024, and both Bitcoin and Ethereum developers are working on migration paths. Our coverage of funding for Bitcoin’s quantum defences and banks’ custody readiness follows the work.
Upgrade tracker
| Upgrade | Network | Status | What it does |
|---|---|---|---|
| Pectra | Ethereum | Live since May 2025 | Let regular wallets act like smart accounts (EIP-7702) and raised the validator balance limit |
| Fusaka | Ethereum | Live since Dec. 2025 | PeerDAS data sampling; cheaper rollup data |
| Glamsterdam | Ethereum | On Sepolia testnet since Oct. 6, 2026; mainnet not yet scheduled | Enshrined proposer-builder separation and block-level access lists for parallel processing |
| Hegotá | Ethereum | Planning | Candidate features include frame transactions |
| Shielded transactions proposal | Bitcoin | Proposal stage | Optional private transfers |
More on the Ethereum roadmap is on the Ethereum hub, including our reports on the Glamsterdam testnet launch and the frame transactions plan.
Crypto tech: FAQ
What is a layer 2 in crypto?
A separate network that processes transactions off a main chain such as Ethereum and settles the results back on it, which cuts fees.
What is a smart contract?
A program stored on a blockchain that runs automatically when called, without a company in the middle.
Can quantum computers break Bitcoin today?
No. Current machines are many orders of magnitude too small. Developers are preparing post-quantum signatures well in advance.
Do network upgrades require holders to do anything?
Almost never. Node operators and platforms update their software. People holding coins on a platform, in an ETF or in a hardware wallet don’t need to act, and anyone who says otherwise to get a seed phrase is running a scam.
General information only, not investment or technical advice.
