UTXO (Unspent Transaction Output)

Definition

UTXO is an accounting model where transaction outputs exist as discrete, indivisible units until spent. Like physical cash, you spend whole UTXOs and receive change. UTXO model provides better privacy and parallelization than account-based systems.

Technical Explanation

UTXO mechanics: transactions consume inputs (previous UTXOs) and create outputs (new UTXOs). Total inputs must equal or exceed outputs plus fees. "Change" returns to sender as a new UTXO. Each UTXO is locked by a spending condition (usually signature).

Post-quantum UTXO: spending conditions use quantum-resistant signatures. Public keys may be hashed (address) until spending, providing partial quantum protection for unused UTXOs—quantum attackers can't derive keys from addresses.

SynX Relevance

SynX's UTXO model locks outputs with quantum-resistant spending conditions. SPHINCS+ signatures authorize spending. Unspent outputs remain protected even if public keys are eventually exposed—address hashing adds defense-in-depth.

Frequently Asked Questions

What's better: UTXO or account model?: UTXO: better privacy, parallelization. Account: simpler smart contracts. Both can be quantum-resistant.
Why do I have multiple UTXOs?: Each received payment creates a UTXO. Your balance is the sum of your unspent outputs.
Does UTXO affect quantum resistance?: UTXOs with hashed public keys have extra protection—keys aren't revealed until spending.

Discrete quantum-resistant outputs. UTXO security with SynX