Avalanche Bridge is the canonical bridge to move assets to and from Avalanche's C-Chain. Assets are locked on the source chain and minted on the Avalanche network.
The Avalanche bridge is a two-way token bridge that allows seamless transfers between the Avalanche C-Chain and Ethereum. Users who wish to use ERC-20 assets within the Avalanche network must first lock their assets in the ChainBridge contract, after which an equivalent token will be minted on Avalanche and sent to the specified user address.
The Avalanche bridge can be broken down into two main parts: the SGX application and a group of third-party indexers and verifiers called "bridge nodes". The nodes are responsible for indexing the Avalanche and Ethereum networks and submitting eligible transactions to the enclave for processing. The Intel SGX application consists of a trusted codebase that runs within an enclave and an untrusted codebase that runs outside. The SGX application requires 6 of 8 nodes to submit the same transaction before generating the signed transaction to process the transfer on the destination chain. The current group of trusted bridge nodes include Ankr, Blockdaemon, Chainstack, Protofire, Avascan, Ava Labs, Bware Labs and Halborn.
The Avalanche bridge is secured by Intel SGX technology. This technology restricts how transfers are performed and nobody (including system administrators) has access to the keys that control the funds. All bridge transfers must be signed by 6 of 8 third-party nodes that also secure and backup an encrypted piece of the bridge's key to enable reconstitution in the event of a hardware failure. Bridge nodes are security tested on a quarterly basis to ensure adherence to strict security standards.