Encyclopedia DeFi · Entry 67
Blockchain bridges: verifying an event across separate systems
In this article
At a glance
Key facts
| Fact | Detail | Source |
|---|---|---|
| Separate states | Each chain has its own transaction history and settlement conditions. | [1] |
| Models | Lock/mint, burn/mint and liquidity delivery are different mechanisms. | [1] |
| Control | Privileged roles can affect contract operations where implemented. | [2] |
The destination needs a reason to accept the event
Moving a token balance between independent ledgers is not a single ordinary transfer. A destination contract needs evidence or an authorized statement that an event occurred on the origin chain. The bridge determines who or what can provide that assurance.
An example message might mean that ten units were locked for a particular recipient. If the destination accepts a false or replayed message, its resulting token accounting can disagree with backing. Verification and replay protection are therefore part of the asset’s meaning.
Follow the assets as well as the message
In a lock-and-mint design, origin assets remain locked and a destination representation is created. A return path can burn the representation and release the locked asset. A burn-and-mint design instead depends on authorized issuance across chains.
A liquidity-based transfer can pay the recipient from existing destination funds and settle the provider’s imbalance separately. Across’s documentation, checked October 2, 2026, describes relayers fronting destination capital before a separate reimbursement process. These models should not be combined into a universal description that every bridge simply moves the same coins.
Completion has several possible meanings
A wallet may show origin-chain inclusion before the bridge’s verification window finishes or the destination action executes. Source finality, message acceptance and recipient delivery are different milestones. Delays need to be interpreted against that bridge’s design. The rollup scenario in Follow a Transaction separates local inclusion from settlement milestones.
Record verification parties or proof system, upgrade authority, pause powers, supported asset and exact exit path. Several bridges to the same chain can have materially different dependencies. Calling both endpoints secure does not establish the security of the connection between them.
Direct answers
Questions people ask
Are bridged tokens identical to issuer-native tokens?
Not necessarily. A bridged representation can be backed by assets locked under a bridge, whereas a native burn-and-mint transfer extinguishes the source token and creates the issuer’s token on the destination. Circle’s CCTP provides the latter example for USDC. Compare the actual token contracts and exit paths.
Inspect the evidence
The answer and key facts have stable claim links. These records retain the scope and qualification when reused.
A blockchain bridge connects activity on separate chains by verifying or attesting to events and authorizing a corresponding action elsewhere. Some lock assets and mint a representation; others burn and mint or deliver existing liquidity. Security depends on the specific verification, custody and upgrade design.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimSeparate states: Each chain has its own transaction history and settlement conditions.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimModels: Lock/mint, burn/mint and liquidity delivery are different mechanisms.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimControl: Privileged roles can affect contract operations where implemented.
Scope: DeFi. Verification: verified · 2026-10-02T15:08:18.373Z.
Link to this claimRevision history
- — First publication after primary-source research and independent automated verification.
- — Before first publication, independent review checked and revised: quickAnswerSourceIds, sections, faq, sources, related. Replaced mismatched introductory-page locator with the developer bridge reference, and independently read ERC-5164 message uniqueness/execution/security requirements, Across destination capital/settlement and Circle CCTP native burn-and-mint. Added source support for replay protection, separately reimbursed liquidity delivery and native-token comparison. ERC-5164 is labeled Last Call, not universal implementation proof. Across example is dated to actual check; no universal bridge duration/security guarantee is asserted. Related links reach native/bridged stablecoins and Ethereum layer2; the existing rollup tool distinguishes local inclusion from settlement and withdrawal milestones.
Source register
Sources and references
Retrieval dates and locators are recorded individually.- Introduction to blockchain bridgesethereum.org contributors
Lock/mint, burn/mint and liquidity-based transfers have different trust assumptions.
Locator: How do bridges work?; Bridge types; Risk with bridges · Retrieved: 2026-10-02Open source - Access controlOpenZeppelin
Ownership, roles, administrator authority and timelock limitations.
Locator: Ownership and Ownable; Role-Based Access Control; Delayed operation · Version / scope: OpenZeppelin Contracts 5.x · Retrieved: 2026-10-02Open source - ERC-5164: Cross-Chain ExecutionEthereum Improvement Proposals
An interface specification showing unique message identifiers, origin validation and replay protection; implementation security is separate.
Locator: MessageDispatcher; MessageExecutor; Security Considerations · Version / scope: ERC-5164 Last Call, retrieved 2026-10-02 · Retrieved: 2026-10-02Open source - Intent Architecture in AcrossAcross Protocol
Relayers front destination capital and are reimbursed through a separate settlement process.
Locator: Competitive Relayer Network; Settlement Layer; How Settlement Flows · Version / scope: Documentation retrieved 2026-10-02 · Retrieved: 2026-10-02Open source - Cross-Chain Transfer ProtocolCircle
USDC is transferred by native burn-and-mint rather than a traditional bridge liquidity pool.
Locator: Overview; CCTP for non-USDC assets · Version / scope: Documentation retrieved 2026-10-02 · Retrieved: 2026-10-02Open source
Research and drafting use AI assistance. A separate automated review checks claims against primary sources; no external expert or named human review is implied. Publication, substantive editing, source retrieval and verification are recorded separately. This version was independently checked by an automated reviewer on 2 October 2026.
Editorial method and correctionsDegrees of Satoshi editorial project. “Blockchain bridges: verifying an event across separate systems.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/blockchain-bridges/