Client-side validation
Also · Single-use seal · Off-chain state
Client-side validation keeps contract state off-chain with its owners and uses Bitcoin only to commit to state changes, through single-use seals on UTXOs. RGB is built on it.
Most blockchains ask every node to validate every contract. Client-side validation turns this around. Only the parties to a transfer hold and check its history. The chain never sees the contract, only a tiny commitment hidden in an ordinary Bitcoin transaction.
The trick that prevents cheating is the single-use seal, a concept due to Peter Todd. A piece of off-chain state is bound to a specific UTXO. Spending that UTXO, with a commitment to the new state, “closes” the seal exactly once. Bitcoin thus acts as the referee of uniqueness, nothing more. The result scales without bloating the chain and keeps asset transfers private, at the cost of peers exchanging data directly and keeping their own backups.
In French · Validation côté client
