A NEAR account derives a separate key for every chain it signs on

How Chain Signatures Work

@NEARProtocol's Chain Signatures feature allows a single NEAR account, including smart contracts, to sign and execute transactions on external blockchains without relying on traditional bridges or separate contract deployments. The mechanism is built on a decentralised multi-party computation (MPC) network: rather than any single machine holding a private key, the key is distributed across multiple independent nodes. Each node produces a fragment, and those fragments combine to form one valid joint signature. No individual node ever has access to the complete signing key, which removes the concentrated custodial risk that has made conventional cross-chain bridges a repeated target for exploits.

Each target blockchain gets its own address, derived deterministically from the NEAR account plus a path string. Transaction requests are routed through a signer contract that takes the payload, the derivation path, and the required signature scheme. Because different paths produce different keys, a signature generated for one chain cannot be replayed to authorise a transaction on another. The isolation is enforced at the cryptographic level, not just by policy.

Broader Chain Support and Practical Implications

According to the official NEAR documentation, Chain Signatures currently supports signing for Bitcoin, Solana, Cosmos, XRP, Aptos, Sui, and a range of EVM-compatible networks including Ethereum, BNB Chain, Avalanche, Polygon, and Arbitrum, among others. The MPC network is secured by NEAR staking and, per the NEAR Foundation, also draws on Eigenlayer ETH restakers.

For developers, the practical benefit is meaningful. A single NEAR account can manage interactions across many blockchains without requiring users to hold native gas tokens on each chain. A companion feature called the Multichain Gas Relayer lets users pay transaction fees using NEAR or NEP-141 tokens regardless of the destination network. For DeFi builders, Chain Signatures opens up chains that traditionally lack smart contract functionality, such as Bitcoin and Dogecoin, to more complex financial logic without wrapping assets or introducing bridge-related counterparty risk.

The approach also narrows the attack surface considerably compared with lock-and-mint bridge designs, where a single contract holding locked assets becomes a concentrated point of failure.

Sources:
NEAR Documentation: What are Chain Signatures?
NEAR Foundation: Chain Signatures Launch
The Block: NEAR Protocol Chain Signatures