How do cryptocurrencies work without blockchain?

23 Ağu 02:51

Blockchain isn’t the only game in town for cryptocurrencies—Directed Acyclic Graphs (DAGs) are a solid alternative that ditches the chain entirely. Instead of blocks linked in a linear chain, DAGs structure transactions as a web where each new transaction confirms previous ones, creating a topological order. Systems like IOTA’s Tangle or Nano’s Block Lattice use this to validate transactions in parallel, which cuts confirmation times to seconds and scales with network activity. No miners? No problem—users validate their own transactions by attaching a small proof-of-work (PoW) or staking lightweight work, reducing energy waste compared to Bitcoin’s Proof-of-Work (PoW) consensus. Security in DAGs relies on cumulative weight: older transactions gain more approval weight over time, making attacks economically irrational. A malicious actor would need to amass more computational/validation power than the honest network majority in real-time—a moving target as the DAG grows. But here’s the catch: DAG networks often struggle with initial bootstrapping—the "nothing-at-stake" problem is flipped; without strict Sybil protection (e.g., PoW or reputation systems), spam attacks or low-value transactions can clog the network. Also, decentralization trade‑offs exist: while DAGs avoid blockchain’s monolithic ledger, some implementations centralize validation in high‑activity periods (e.g., wallets or coordinators in early IOTA) to maintain stability. The lack of a global ledger also complicates audit trails, making regulatory scrutiny tougher for DAG‑based projects compared to immutable blockchains.